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RSS2010 Vol. 34, No. 2
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2010, 34(2): 145-148,160.
doi: 10.3969/j.issn.1001-3806.2010.02.001
[Abstract]
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Abstract:
The output beam profile from a heat capacity laser is instantaneously changing because of the temperature continually rising during laser shots.In order to improve the focusing capability of heat capacity laser and realize real time controlling of the far field spot,a cube corner array(CCA) is used as a quasi-phase conjugate mirror to realize a passive and real time compensation of the wave front error.The compensation capability of a thermal insensitive cavity with a cube corner array was studied in detail.The structure of the cube corner array resonator was optimized by using an infra-cavity filter to reject the conjugation mode between different cube comers.The energy concentration of the single mode with an infra-cavity filter was improved to 90%, approximately 4.5 times of the multi-modes without the infra-cavity filter.The focusing ability of such a CCA resonator was improved about 10 times of a traditional planner-concave resonator.The simulation and experiment results show that the cube corner array cavity is thermal insensitive,which can increase the focusing ability of a heat capacity laser.
The output beam profile from a heat capacity laser is instantaneously changing because of the temperature continually rising during laser shots.In order to improve the focusing capability of heat capacity laser and realize real time controlling of the far field spot,a cube corner array(CCA) is used as a quasi-phase conjugate mirror to realize a passive and real time compensation of the wave front error.The compensation capability of a thermal insensitive cavity with a cube corner array was studied in detail.The structure of the cube corner array resonator was optimized by using an infra-cavity filter to reject the conjugation mode between different cube comers.The energy concentration of the single mode with an infra-cavity filter was improved to 90%, approximately 4.5 times of the multi-modes without the infra-cavity filter.The focusing ability of such a CCA resonator was improved about 10 times of a traditional planner-concave resonator.The simulation and experiment results show that the cube corner array cavity is thermal insensitive,which can increase the focusing ability of a heat capacity laser.
2010, 34(2): 149-153.
doi: 10.3969/j.issn.1001-3806.2010.02.002
Abstract:
To apply the laser spot welding process in the joining of NdFeB permanent magnet and steel plate cold commercial(SPCC) steel,the effects of laser pulse power,pulse duration,and defocusing distance on weld features and strength were studied experimentally.The resnlts show that there are both conduction welding and keyhole welding in the laser spot welding under our experimental conditions.Welding modes can be transformed by changing peak power or defocusing distance, but not altered by changing pulse duration.There are three fracture modes in shearing tests,i.e.,exuviation,shear and crash fractures,with nugget dimensions and shearing load increasing in tum.To gain good joint strength,the pulse peak power and defocusing distance shonld be chosen appropriately to implement welding in keyhole mode,and moreover,pulse duration should not be too long.
To apply the laser spot welding process in the joining of NdFeB permanent magnet and steel plate cold commercial(SPCC) steel,the effects of laser pulse power,pulse duration,and defocusing distance on weld features and strength were studied experimentally.The resnlts show that there are both conduction welding and keyhole welding in the laser spot welding under our experimental conditions.Welding modes can be transformed by changing peak power or defocusing distance, but not altered by changing pulse duration.There are three fracture modes in shearing tests,i.e.,exuviation,shear and crash fractures,with nugget dimensions and shearing load increasing in tum.To gain good joint strength,the pulse peak power and defocusing distance shonld be chosen appropriately to implement welding in keyhole mode,and moreover,pulse duration should not be too long.
2010, 34(2): 154-156.
doi: 10.3969/j.issn.1001-3806.2010.02.003
Abstract:
In order to study the impact of the alloying elements on ZL114A aluminum alloy solidification cracking, three aluminum alloy welding wires of different compositions were applied to add various elements to the weld.The impact of these alloy elements on the ZL114A sheet solidification crack sensitivity were analyzed in theory and verified in experiments.The result shows that three main alloy elements Al,Mg and Si element exist close to the solidification crack.It was found that the enrichment of Mg and Si element nearby the solidification crack resulting in the formation of some low melting point eutectics of Al-Si,Mg-Si,Al-Mg2Si at the boundary of columnar crystals.These low melting point eutectics are closely related to the generation of ZL114A aluminum alloy solidification crack.The result is helpful for the study of laser welding ZL114A aluminum alloy solidification cracking in the prospective of metallurgical factors research.
In order to study the impact of the alloying elements on ZL114A aluminum alloy solidification cracking, three aluminum alloy welding wires of different compositions were applied to add various elements to the weld.The impact of these alloy elements on the ZL114A sheet solidification crack sensitivity were analyzed in theory and verified in experiments.The result shows that three main alloy elements Al,Mg and Si element exist close to the solidification crack.It was found that the enrichment of Mg and Si element nearby the solidification crack resulting in the formation of some low melting point eutectics of Al-Si,Mg-Si,Al-Mg2Si at the boundary of columnar crystals.These low melting point eutectics are closely related to the generation of ZL114A aluminum alloy solidification crack.The result is helpful for the study of laser welding ZL114A aluminum alloy solidification cracking in the prospective of metallurgical factors research.
2010, 34(2): 157-160.
doi: 10.3969/j.issn.1001-3806.2010.02.004
Abstract:
The system of measuring temporal profile for multi-beam of near infrared was developed, considering the multi-beams, the narrow pulse width of each beam, the great aperture of beam of light, and the large far-field drift for high power laser facility.The beam uniform assemble for fiber sampling of beam coupling was used,the technique of time multiplexing for the delay of time was adopted, and the power time history in the SG-Ⅲ prototype laser facility's 8 beam laser was measured.After measuring and analyzing the temporal profile the SG-Ⅲ prototype laser facility made in 2008,the relative expanded uncertainty of the measuring system was less than 2.5%.The results showed that the anti-jamming ability of the measuring system was improved.The measuring system is much more reliable and costly.
The system of measuring temporal profile for multi-beam of near infrared was developed, considering the multi-beams, the narrow pulse width of each beam, the great aperture of beam of light, and the large far-field drift for high power laser facility.The beam uniform assemble for fiber sampling of beam coupling was used,the technique of time multiplexing for the delay of time was adopted, and the power time history in the SG-Ⅲ prototype laser facility's 8 beam laser was measured.After measuring and analyzing the temporal profile the SG-Ⅲ prototype laser facility made in 2008,the relative expanded uncertainty of the measuring system was less than 2.5%.The results showed that the anti-jamming ability of the measuring system was improved.The measuring system is much more reliable and costly.
2010, 34(2): 161-163,209.
doi: 10.3969/j.issn.1001-3806.2010.02.005
Abstract:
In order to study the influence of laser texturing on the performance of a drawing surface,the characteristics of friction behavior and the morphology of laser texturing on the die surface were analyzed.In the view of asperity contacts of laser texturing morphology,the friction coefficient on the laser texturing surface was composed of dry friction and lubrication friction, and the relation model between the friction coefficient and the surface morphology parameters was established,the effect of laser texturing morphology on the surface coefficient of friction was discussed.At last a large number of tribology experiments on laser texturing surface were taken to verify the accuracy of the model.The result shows that laser texturing improved tribology character, and the model provides a theoretical base for further research of laser texturing on drawing mould.
In order to study the influence of laser texturing on the performance of a drawing surface,the characteristics of friction behavior and the morphology of laser texturing on the die surface were analyzed.In the view of asperity contacts of laser texturing morphology,the friction coefficient on the laser texturing surface was composed of dry friction and lubrication friction, and the relation model between the friction coefficient and the surface morphology parameters was established,the effect of laser texturing morphology on the surface coefficient of friction was discussed.At last a large number of tribology experiments on laser texturing surface were taken to verify the accuracy of the model.The result shows that laser texturing improved tribology character, and the model provides a theoretical base for further research of laser texturing on drawing mould.
2010, 34(2): 164-167.
doi: 10.3969/j.issn.1001-3806.2010.02.006
Abstract:
In order to solve the low efficiency problem of symbol synchronization in laser communication,a super-frame synchronization was proposed instead of symbol synchronization.On the basis of analyzing multi-pulse position moudulation (MPPM)code pattern and length,the different methods of combination Barker sequence applied in the super-frame synchronization of MPPM were analyzed, and the length of synchronization code of the different frame was calculated.The simulation results show that this method can decode the input binary bits accurately.The obtained results have theoretic reference value for the improving the performance of laser communication.
In order to solve the low efficiency problem of symbol synchronization in laser communication,a super-frame synchronization was proposed instead of symbol synchronization.On the basis of analyzing multi-pulse position moudulation (MPPM)code pattern and length,the different methods of combination Barker sequence applied in the super-frame synchronization of MPPM were analyzed, and the length of synchronization code of the different frame was calculated.The simulation results show that this method can decode the input binary bits accurately.The obtained results have theoretic reference value for the improving the performance of laser communication.
2010, 34(2): 168-169,213.
doi: 10.3969/j.issn.1001-3806.2010.02.007
Abstract:
Besides main specula and diffraction spots,in order to prove bright points distributing regularly adjacent to main facular with 3CCD irradiated by laser,it was explained by the theory of Fourier optics and simulated numerically.The results of numerical simulation agree approximately with the experimental observation.It is found that the bright points distributed regularly adjacent to main facular is spectral distribution on the focal plane of the array of lens when the laser irradiates a hexagonal aperture,rather than what is induced by stray light.
Besides main specula and diffraction spots,in order to prove bright points distributing regularly adjacent to main facular with 3CCD irradiated by laser,it was explained by the theory of Fourier optics and simulated numerically.The results of numerical simulation agree approximately with the experimental observation.It is found that the bright points distributed regularly adjacent to main facular is spectral distribution on the focal plane of the array of lens when the laser irradiates a hexagonal aperture,rather than what is induced by stray light.
2010, 34(2): 170-172.
doi: 10.3969/j.issn.1001-3806.2010.02.008
Abstract:
In order to study laser Doppler effect, a simple experimental system was set up to measure Doppler effect by means of laser heterodyne interferometer technique.Two sets of experimental data were obtained.At 0.2mm/s of uniform moving velocity,the theoretical and tested beat frequency is 316.0556Hz and 312.0434Hz respectively.At 0.1mm/s of uniform moving velocity,the theoretical and tested beat frequency is 158.0278Hz and 151.6055Hz respectively.Measurement results clearly show the effectiveness of the proposed setup and the simple optical system would be a new and interesting aid for the experiment teaching of classical optics.
In order to study laser Doppler effect, a simple experimental system was set up to measure Doppler effect by means of laser heterodyne interferometer technique.Two sets of experimental data were obtained.At 0.2mm/s of uniform moving velocity,the theoretical and tested beat frequency is 316.0556Hz and 312.0434Hz respectively.At 0.1mm/s of uniform moving velocity,the theoretical and tested beat frequency is 158.0278Hz and 151.6055Hz respectively.Measurement results clearly show the effectiveness of the proposed setup and the simple optical system would be a new and interesting aid for the experiment teaching of classical optics.
2010, 34(2): 173-177.
doi: 10.3969/j.issn.1001-3806.2010.02.009
Abstract:
A model of the relationship between pulse-laser parameters and the pattern of electroless deposit composite coatings(taking into account hardened width,depth and melting state) with a back propagation neural network was constructed in order to explore the theoretical principles underlying pulse-laser reinforcement of plating coatings.The momentum-adaptive learning rate algorithm was selected to increase network stability,training speed and accuracy.The appearance of composite coating was effectively predicted with ±8.33% relative error.This method is a new way of exploring the theoretical principles of pulse-laser coating-reinforcement.
A model of the relationship between pulse-laser parameters and the pattern of electroless deposit composite coatings(taking into account hardened width,depth and melting state) with a back propagation neural network was constructed in order to explore the theoretical principles underlying pulse-laser reinforcement of plating coatings.The momentum-adaptive learning rate algorithm was selected to increase network stability,training speed and accuracy.The appearance of composite coating was effectively predicted with ±8.33% relative error.This method is a new way of exploring the theoretical principles of pulse-laser coating-reinforcement.
2010, 34(2): 178-180,217.
doi: 10.3969/j.issn.1001-3806.2010.02.010
Abstract:
For the sake of studying isentropic compression of plane material irradiated by laser,based on the model of 1-D stress loading and entropy increase.The evolution of compression ratio,stress and entropy increase of plane material's Lagrangian points were computed with Lagrangian method and the existing experimental data.The simulation results are consistent with reported experimental results and show the basic characterization parameters, such as particle velocity, material specific heat,Hugoniot parameters and Griineisen coefficient.Quasic-isentropic compression can be judged with these parameters.
For the sake of studying isentropic compression of plane material irradiated by laser,based on the model of 1-D stress loading and entropy increase.The evolution of compression ratio,stress and entropy increase of plane material's Lagrangian points were computed with Lagrangian method and the existing experimental data.The simulation results are consistent with reported experimental results and show the basic characterization parameters, such as particle velocity, material specific heat,Hugoniot parameters and Griineisen coefficient.Quasic-isentropic compression can be judged with these parameters.
2010, 34(2): 181-184.
doi: 10.3969/j.issn.1001-3806.2010.02.011
Abstract:
In order to calculate the pressure of the photo-thermolysis induced by the microscopic laser beam during fractional laser resurfacing, numerical simulation was performed by means of the mathematics model of the photo-thermolysis interaction between fractional Er:YAG and skin.The results are that the skin tissue can be evaporated other than carbonized immediately and a great pressure with very short pulse duration will appear, if the laser power density was controlled within a reasonable range.It is concluded that reasonable laser power density during fractional Er:YAG treatment can minimize the pain and the laser-induced thermal injury to the surrounding tissues during surgery.The computing results are consistent with the experiment results reported abroad.
In order to calculate the pressure of the photo-thermolysis induced by the microscopic laser beam during fractional laser resurfacing, numerical simulation was performed by means of the mathematics model of the photo-thermolysis interaction between fractional Er:YAG and skin.The results are that the skin tissue can be evaporated other than carbonized immediately and a great pressure with very short pulse duration will appear, if the laser power density was controlled within a reasonable range.It is concluded that reasonable laser power density during fractional Er:YAG treatment can minimize the pain and the laser-induced thermal injury to the surrounding tissues during surgery.The computing results are consistent with the experiment results reported abroad.
2010, 34(2): 185-188.
doi: 10.3969/j.issn.1001-3806.2010.02.012
Abstract:
For studying the effects of atmospheric scattering to optical signals,taking rain particles as an example, starting from its physical properties and employing Mie scattering theory and Joss raindrop spectrum distribution, the light intensity attenuation coefficient caused by rain particles'scattering was calculated.On this basis,the scattering effect on the performance of the free space optical communication orthogonal frequency division multiplexing(FSO-OFDM) system was analyzed.The results show that the FSO-OFDM system performance in scattering channel primarily depends on the variance of light intensity caused by scattering,secondly depends on light intensity attenuation coefficient caused by scattering.
For studying the effects of atmospheric scattering to optical signals,taking rain particles as an example, starting from its physical properties and employing Mie scattering theory and Joss raindrop spectrum distribution, the light intensity attenuation coefficient caused by rain particles'scattering was calculated.On this basis,the scattering effect on the performance of the free space optical communication orthogonal frequency division multiplexing(FSO-OFDM) system was analyzed.The results show that the FSO-OFDM system performance in scattering channel primarily depends on the variance of light intensity caused by scattering,secondly depends on light intensity attenuation coefficient caused by scattering.
2010, 34(2): 189-192.
doi: 10.3969/j.issn.1001-3806.2010.02.013
Abstract:
In order to study the physical model of the ultrashort pulses with spatial profiles of elegant Laguerre-Gaussian transverse modes and the effect of beam parameters on the model, complex amplitude envelope(CAE)solution and complex analytical signal(CAS)solution of pulsed beams were derived according to CAE and CAS representations.Generation of the singularity in the CAE solution and effect of the chirp,the pulse duration and the mode on it were analyzed.The results indicate that singularity of the CAE solution closer to the central with larger chirp and the CAS solution doesnt present singularity with any chirp.The singularity is located nearer to the central axis for the pulses with higher order transverse modes and shorter pulse duration.Thus, to obtain reasonable physical model of the laser beams,appropriate method should be adopted according to the beam parameters.
In order to study the physical model of the ultrashort pulses with spatial profiles of elegant Laguerre-Gaussian transverse modes and the effect of beam parameters on the model, complex amplitude envelope(CAE)solution and complex analytical signal(CAS)solution of pulsed beams were derived according to CAE and CAS representations.Generation of the singularity in the CAE solution and effect of the chirp,the pulse duration and the mode on it were analyzed.The results indicate that singularity of the CAE solution closer to the central with larger chirp and the CAS solution doesnt present singularity with any chirp.The singularity is located nearer to the central axis for the pulses with higher order transverse modes and shorter pulse duration.Thus, to obtain reasonable physical model of the laser beams,appropriate method should be adopted according to the beam parameters.
2010, 34(2): 193-196,201.
doi: 10.3969/j.issn.1001-3806.2010.02.014
Abstract:
In order to obtain the steady state fluorescent and synchronous fluorescent spectral characteristics of milk powder, melamine and the mixture of milk powder-melamine respectively, UV light of 280nm was chosen as the excitation light to irradiate milk powder-water solution and the emission peak was at 330nm in the fluorescent spectrum. The constant-wavelength Δλ was used in synchronous fluorescence spectrometry. The experiment results reveal while changing the value of DA,the synchronous fluorescent intensity altered, and it reached maximum when Δλ=60nm. Scanning the synchronous fluorescence of different milk powder-water solutions with Δλ=60nm, the fluorescent intensity changed and the relationship between the fluorescence intensity and the concentration of the milk powder-water solution was linear. When Δλ=38nm, the synchronous fluorescent spectra of milk powder, melamine and the mixture of melamine and milk powder were obtained. The experiment results indicated that the synchronous fluorescent peak of milk powder was at 283nm, for melamine,it was at 319nm.In the milk powder-melamine solutions,there were two peaks of 283nm for milk powder and 319nm for melamine, so that whether there was melamine in the milk powder can be determined.The research may contribute to the research of the characteristics of melamine and its derivatives and the detection of melamine in the milk.
In order to obtain the steady state fluorescent and synchronous fluorescent spectral characteristics of milk powder, melamine and the mixture of milk powder-melamine respectively, UV light of 280nm was chosen as the excitation light to irradiate milk powder-water solution and the emission peak was at 330nm in the fluorescent spectrum. The constant-wavelength Δλ was used in synchronous fluorescence spectrometry. The experiment results reveal while changing the value of DA,the synchronous fluorescent intensity altered, and it reached maximum when Δλ=60nm. Scanning the synchronous fluorescence of different milk powder-water solutions with Δλ=60nm, the fluorescent intensity changed and the relationship between the fluorescence intensity and the concentration of the milk powder-water solution was linear. When Δλ=38nm, the synchronous fluorescent spectra of milk powder, melamine and the mixture of melamine and milk powder were obtained. The experiment results indicated that the synchronous fluorescent peak of milk powder was at 283nm, for melamine,it was at 319nm.In the milk powder-melamine solutions,there were two peaks of 283nm for milk powder and 319nm for melamine, so that whether there was melamine in the milk powder can be determined.The research may contribute to the research of the characteristics of melamine and its derivatives and the detection of melamine in the milk.
2010, 34(2): 197-201.
doi: 10.3969/j.issn.1001-3806.2010.02.015
Abstract:
For the propose of improving the anti-jamming ability of a laser pulse shape measuring system,the laser pulse propagation model was established, the linear characteristics of a nanosecond pulse propagating in fibers were analyzed,and factors affecting the pulse transmission characteristics were evaluated systematically.The laser pulse shape was measured with a nanosecond laser pulse propagating through single and multi-mold fiber in different length.The width of the pulse transmitted by the fiber was compared to that of a fraction of the pulse propagating over an air path.The critical condition of pulse broadening acceptable within measuring error was obtained. The conclusion provides guidance to design the laser pulse shape measuring system of the SG-Ⅲ laser facility.
For the propose of improving the anti-jamming ability of a laser pulse shape measuring system,the laser pulse propagation model was established, the linear characteristics of a nanosecond pulse propagating in fibers were analyzed,and factors affecting the pulse transmission characteristics were evaluated systematically.The laser pulse shape was measured with a nanosecond laser pulse propagating through single and multi-mold fiber in different length.The width of the pulse transmitted by the fiber was compared to that of a fraction of the pulse propagating over an air path.The critical condition of pulse broadening acceptable within measuring error was obtained. The conclusion provides guidance to design the laser pulse shape measuring system of the SG-Ⅲ laser facility.
2010, 34(2): 202-205.
doi: 10.3969/j.issn.1001-3806.2010.02.016
Abstract:
In order to prove that there are steady-sate incoherent coupled screening-photovoltaic soliton pairs in biased two-photon photovoltaic photorefractive crystals under steady-state conditions,the coupling of two incoherent optical beams with the same polarization and wavelength in two-photon photovoltaic photorefractive crystals is theoretically studied.The result shows that these soliton pairs are established by the incoherent solitary beams with the same polarization and wavelength. The screening-photovoltaic soliton pairs can be considered as the united form of screening soliton pairs and closed-circuit photovoltaic soliton pairs.They reduce to screening soliton pairs in the absence of photovoltaic effect, whereas they become photovoltaic soliton pairs under the closed circuit condition when the bias field is not applied.It is shown that incoherently coupled dark-dark and bright-bright screening-photovoltaic soliton pairs are possible due to two-photon photorefractive effect.
In order to prove that there are steady-sate incoherent coupled screening-photovoltaic soliton pairs in biased two-photon photovoltaic photorefractive crystals under steady-state conditions,the coupling of two incoherent optical beams with the same polarization and wavelength in two-photon photovoltaic photorefractive crystals is theoretically studied.The result shows that these soliton pairs are established by the incoherent solitary beams with the same polarization and wavelength. The screening-photovoltaic soliton pairs can be considered as the united form of screening soliton pairs and closed-circuit photovoltaic soliton pairs.They reduce to screening soliton pairs in the absence of photovoltaic effect, whereas they become photovoltaic soliton pairs under the closed circuit condition when the bias field is not applied.It is shown that incoherently coupled dark-dark and bright-bright screening-photovoltaic soliton pairs are possible due to two-photon photorefractive effect.
2010, 34(2): 206-209.
doi: 10.3969/j.issn.1001-3806.2010.02.017
Abstract:
In order to increase the measuring distance and improve the interference signal, Eased on conventional three-mirror structure, a new structure with a compensative mirror in the external cavity was put forward.The new structure was studied experimentally and theoretically. The experimental results showed that the measuring distance increased from 20cm to 60cm, signals with a compensative mirror were strengthened and more stable than those without compensative mirrors.The experimental results also showed that different results produced for different location and reflectivity of the compensative mirror. Based on propagating theory,the model of the structure was deduced, and simulated by means of MATLAB software.The simulation results agreed well with those of experimental results.The results showed that the compensative structure conquered many weaknesses of the conventional self-mixing system.It has provided a useful reference for self-mixing interference measurement in practical way.
In order to increase the measuring distance and improve the interference signal, Eased on conventional three-mirror structure, a new structure with a compensative mirror in the external cavity was put forward.The new structure was studied experimentally and theoretically. The experimental results showed that the measuring distance increased from 20cm to 60cm, signals with a compensative mirror were strengthened and more stable than those without compensative mirrors.The experimental results also showed that different results produced for different location and reflectivity of the compensative mirror. Based on propagating theory,the model of the structure was deduced, and simulated by means of MATLAB software.The simulation results agreed well with those of experimental results.The results showed that the compensative structure conquered many weaknesses of the conventional self-mixing system.It has provided a useful reference for self-mixing interference measurement in practical way.
2010, 34(2): 210-213.
doi: 10.3969/j.issn.1001-3806.2010.02.018
Abstract:
To measure the frequency and amplitude of low-frequency liquid surface wave, a detection method based on the principle of Doppler interferometry for velocity measurement is proposed, which makes use of interference between laser scattered on liquid surface and reference beams. Theoretical analysis was carried out to achieve the analytical expression for Doppler shift and amplitude of liquid surface wave.Also, the feasibility of demodulating frequency of low-frequency liquid surface wave from the spectrum was evaluated with Bessel functions.A test system was designed and implemented for Doppler interferometry for liquid surface wave. The test results show that parameters of liquid surface wave at 10Hz～40Hz can be measured accurately. This method provides a new solution for detection of liquid surface wave.
To measure the frequency and amplitude of low-frequency liquid surface wave, a detection method based on the principle of Doppler interferometry for velocity measurement is proposed, which makes use of interference between laser scattered on liquid surface and reference beams. Theoretical analysis was carried out to achieve the analytical expression for Doppler shift and amplitude of liquid surface wave.Also, the feasibility of demodulating frequency of low-frequency liquid surface wave from the spectrum was evaluated with Bessel functions.A test system was designed and implemented for Doppler interferometry for liquid surface wave. The test results show that parameters of liquid surface wave at 10Hz～40Hz can be measured accurately. This method provides a new solution for detection of liquid surface wave.
2010, 34(2): 218-220,223.
doi: 10.3969/j.issn.1001-3806.2010.02.020
Abstract:
The propagation and evolution characteristics of ultra-short pulses in a nonlinearity-increasing fiber were studied based on theoretical analysis and numerical calculation. Numerical simulation shows that the propagation in a nonlinearity-increasing fiber is similar with that in a gain-amplification fiber or dispersion fiber, i.e., the propagation and evolution accords with the self-similar evolution. Finally the parabolic pulse with linear chirp can be achieved. The result is useful for pulse compression because the parabolic pulse has linear chirp.
The propagation and evolution characteristics of ultra-short pulses in a nonlinearity-increasing fiber were studied based on theoretical analysis and numerical calculation. Numerical simulation shows that the propagation in a nonlinearity-increasing fiber is similar with that in a gain-amplification fiber or dispersion fiber, i.e., the propagation and evolution accords with the self-similar evolution. Finally the parabolic pulse with linear chirp can be achieved. The result is useful for pulse compression because the parabolic pulse has linear chirp.
2010, 34(2): 221-223.
doi: 10.3969/j.issn.1001-3806.2010.02.021
Abstract:
The characteristic that the return signals of a Raman lidar are not affected by aerosol backscattering can be used to calibrate lidar constant. At homogenous horizontal atmosphere, the lidar constant can be calculated with knowledge about Raman diffusion back scattering cross section and number density of N2. Numerical simulation was carried out and 4.688% relative error of the lidar constant was obtained. Theoretical derivation and numerical simulation indicate the feasibility of the method. The achievement of lidar constant will offer convenience for retrieve of aerosol in lidar equation and evaluation of a lidar system.
The characteristic that the return signals of a Raman lidar are not affected by aerosol backscattering can be used to calibrate lidar constant. At homogenous horizontal atmosphere, the lidar constant can be calculated with knowledge about Raman diffusion back scattering cross section and number density of N2. Numerical simulation was carried out and 4.688% relative error of the lidar constant was obtained. Theoretical derivation and numerical simulation indicate the feasibility of the method. The achievement of lidar constant will offer convenience for retrieve of aerosol in lidar equation and evaluation of a lidar system.
2010, 34(2): 224-226,231.
doi: 10.3969/j.issn.1001-3806.2010.02.022
Abstract:
In order to obtain laser at multiple wavelengths, a modified multi-wavelength actively mode-locked fiber ring laser was proposed and experimentally demonstrated. In this kind of laser, stable multi-wavelength lasing is achieved by integrating cascaded sampled fiber Bragg gratings(SFBGs) into the laser cavity.To implement actively mode-locking technique, a double-ring cavity configuration was used to assure that the cavity lengths for all wavelengths lasing are identical.Thus, simultaneous mode locking of all wavelengths was successfully achieved by using the same mode-locking signal.It was shown in our experiments that up to 14 wavelengths were successfully demonstrated with a wavelength spacing of 1.6 nm.The output power was more than OdBm and the side mode suppression ratio was about 30dB. The highest mode-locking frequency was 1.05 GHz and the pulse-width of output pulse trains was 216ps.
In order to obtain laser at multiple wavelengths, a modified multi-wavelength actively mode-locked fiber ring laser was proposed and experimentally demonstrated. In this kind of laser, stable multi-wavelength lasing is achieved by integrating cascaded sampled fiber Bragg gratings(SFBGs) into the laser cavity.To implement actively mode-locking technique, a double-ring cavity configuration was used to assure that the cavity lengths for all wavelengths lasing are identical.Thus, simultaneous mode locking of all wavelengths was successfully achieved by using the same mode-locking signal.It was shown in our experiments that up to 14 wavelengths were successfully demonstrated with a wavelength spacing of 1.6 nm.The output power was more than OdBm and the side mode suppression ratio was about 30dB. The highest mode-locking frequency was 1.05 GHz and the pulse-width of output pulse trains was 216ps.
2010, 34(2): 227-231.
doi: 10.3969/j.issn.1001-3806.2010.02.023
Abstract:
In order to improve tribological property of motorcycle engine piston ring and cylinder liner and fuel economy characteristic,the technology of laser surface texturing was used to make regular micro geometric structure on the cylinder liner.The theoretical lubricating model of uniform distribution micro geometric structure in the form of micro pores was developed, including the Reynolds equation, oil-film thickness equation and dynamics equation.The model was solved by means of multi-grid method and the hydrodynamic pressure and oil-film thickness distribution were obtained. The results show that surface texturing can be used to maintain hydrodynamic effects and improve the lubrication performance efficiently, even with nominal parallel surfaces.
In order to improve tribological property of motorcycle engine piston ring and cylinder liner and fuel economy characteristic,the technology of laser surface texturing was used to make regular micro geometric structure on the cylinder liner.The theoretical lubricating model of uniform distribution micro geometric structure in the form of micro pores was developed, including the Reynolds equation, oil-film thickness equation and dynamics equation.The model was solved by means of multi-grid method and the hydrodynamic pressure and oil-film thickness distribution were obtained. The results show that surface texturing can be used to maintain hydrodynamic effects and improve the lubrication performance efficiently, even with nominal parallel surfaces.
2010, 34(2): 240-242,246.
doi: 10.3969/j.issn.1001-3806.2010.02.026
Abstract:
In order to overcome the main issue in the design of high power fast axial flow CO2 lasers, i.e.,cleanup of the heat in the active region, considering the inner heat cycle and characteristics of the 7kW fast axial flow CO2 laser, the heat balance equation was established with connective cooling method.Meanwhile,in view of the big thermal load quantity, the whole sturcture limitation and the specific turbo blower of the high power laser, comparing various types of heat exchangers, the rectangle fin circle tube heat exchanger was chosen as the laser's radiator in light of the prominent heat transfer u:apacity and compact structure. Further more designed the heat exchanger and calculated the heat conducting for the 7kW laser.The quantity of heat exchange is 37.4kW.The results indicate that the rectangle fin circle tube heat exchanger is suitable to the fast axial flow CO2 laser.
In order to overcome the main issue in the design of high power fast axial flow CO2 lasers, i.e.,cleanup of the heat in the active region, considering the inner heat cycle and characteristics of the 7kW fast axial flow CO2 laser, the heat balance equation was established with connective cooling method.Meanwhile,in view of the big thermal load quantity, the whole sturcture limitation and the specific turbo blower of the high power laser, comparing various types of heat exchangers, the rectangle fin circle tube heat exchanger was chosen as the laser's radiator in light of the prominent heat transfer u:apacity and compact structure. Further more designed the heat exchanger and calculated the heat conducting for the 7kW laser.The quantity of heat exchange is 37.4kW.The results indicate that the rectangle fin circle tube heat exchanger is suitable to the fast axial flow CO2 laser.
2010, 34(2): 247-249,288.
doi: 10.3969/j.issn.1001-3806.2010.02.028
Abstract:
In order to solve the problem of the inversion ellipsometric parameter of transparent film on transparent substrate with iteration, the data processing method was analyzed in theory and verified in experiments.When the refractive index of film is closing to the refractive index of substrate,a mistake should happen in ellipsometric data inversion. According to the analysis,a new sub-iterative search method was presented to overcome the problem and a program of ellipsometric data processing was designed successfully with the tool of Labview.Finally,some of the samples were measured and the result compared with those presented in some literature.The experimental results show that the ellipsometric parameter of single-layer transparent film on transparent substrate is computed successfully,and the inversion have the advantages of high stability,speed and precision of up to 0.03nm.
In order to solve the problem of the inversion ellipsometric parameter of transparent film on transparent substrate with iteration, the data processing method was analyzed in theory and verified in experiments.When the refractive index of film is closing to the refractive index of substrate,a mistake should happen in ellipsometric data inversion. According to the analysis,a new sub-iterative search method was presented to overcome the problem and a program of ellipsometric data processing was designed successfully with the tool of Labview.Finally,some of the samples were measured and the result compared with those presented in some literature.The experimental results show that the ellipsometric parameter of single-layer transparent film on transparent substrate is computed successfully,and the inversion have the advantages of high stability,speed and precision of up to 0.03nm.
2010, 34(2): 250-252.
doi: 10.3969/j.issn.1001-3806.2010.02.029
Abstract:
In order to optimize the design of a fiber Raman laser, a numerical model is adopted for a cascaded Raman fiber laser, and a new numerical algorithm is described including Runge-Kutta and the least squares methods that can be applied to cascaded Raman fiber lasers.The effects of output reflectivity, fiber length and pump power on the output characteristics of the cascaded Raman fiber laser are studied in detail. The results show that the algorithm makes the model robust and fast and the simulation results are in good agreement with experiments.
In order to optimize the design of a fiber Raman laser, a numerical model is adopted for a cascaded Raman fiber laser, and a new numerical algorithm is described including Runge-Kutta and the least squares methods that can be applied to cascaded Raman fiber lasers.The effects of output reflectivity, fiber length and pump power on the output characteristics of the cascaded Raman fiber laser are studied in detail. The results show that the algorithm makes the model robust and fast and the simulation results are in good agreement with experiments.
2010, 34(2): 253-257.
doi: 10.3969/j.issn.1001-3806.2010.02.030
Abstract:
In order to study the fluorescence spectra of methyl parathion and its characteristics, the spectral characteristics of standard methyl parathion solution induced by UV-light were experimentally studied with a multifunctional spectrometer system.Based on theoretical analysis by means of GAUSSIAN software and the methods of quantum mechanics,the mechanism of the fluorescence spectra of standard methyl parathion solution and the transition energy of methyl parathion were obtained and the transition energy of the linear structure fluorophore was estimated. The experimental valve was a little different from the theoretical value.The results show that there are four fluorescence peaks generated when the standard methyl parathion solution is excited by UV light at the wavelength of 200nm-320mn. The peak position is located at 435nm, 467nm, 567nm and 650nm respectively. The best excitation wavelength is 200nm and 295nm. The four fluorescence peaks are generated by the combined actions of the methyl parathion and the acetone.In methyl parathion molecule, there are the transition of n electrons in nitryl, the transition of electronic structure formed by the oxygen atom and the benzene ring and the transition of n electrons in P=S group.In acetone molecule, there is the transition of n electrons in C=O group. These results are helpful for testing organophosphorus pesticide's content in the area such as food safety inspection.
In order to study the fluorescence spectra of methyl parathion and its characteristics, the spectral characteristics of standard methyl parathion solution induced by UV-light were experimentally studied with a multifunctional spectrometer system.Based on theoretical analysis by means of GAUSSIAN software and the methods of quantum mechanics,the mechanism of the fluorescence spectra of standard methyl parathion solution and the transition energy of methyl parathion were obtained and the transition energy of the linear structure fluorophore was estimated. The experimental valve was a little different from the theoretical value.The results show that there are four fluorescence peaks generated when the standard methyl parathion solution is excited by UV light at the wavelength of 200nm-320mn. The peak position is located at 435nm, 467nm, 567nm and 650nm respectively. The best excitation wavelength is 200nm and 295nm. The four fluorescence peaks are generated by the combined actions of the methyl parathion and the acetone.In methyl parathion molecule, there are the transition of n electrons in nitryl, the transition of electronic structure formed by the oxygen atom and the benzene ring and the transition of n electrons in P=S group.In acetone molecule, there is the transition of n electrons in C=O group. These results are helpful for testing organophosphorus pesticide's content in the area such as food safety inspection.
2010, 34(2): 258-260,264.
doi: 10.3969/j.issn.1001-3806.2010.02.031
Abstract:
In order to study the axial intensity distribution and focal shifts of flattened Gaussian beams(FGBs) passing through an aperture-lens separation system in detail,each parameter affecting the axial optical intensity distribution and focal shift were analyzed through numerical calculation based on Collins formula.It's indicated that the axial intensity distribution and focal shift are not only determined by FGBs orders N and Fresnel number Fw, but also effected by Fresnel number Fa of the aperture and aperture-lens distance s.
In order to study the axial intensity distribution and focal shifts of flattened Gaussian beams(FGBs) passing through an aperture-lens separation system in detail,each parameter affecting the axial optical intensity distribution and focal shift were analyzed through numerical calculation based on Collins formula.It's indicated that the axial intensity distribution and focal shift are not only determined by FGBs orders N and Fresnel number Fw, but also effected by Fresnel number Fa of the aperture and aperture-lens distance s.
2010, 34(2): 261-264.
doi: 10.3969/j.issn.1001-3806.2010.02.032
Abstract:
The effect of the atmospheric turbulence on the bit error rate in a laser communication system with multiple beam transmission and reception was analyzed.Ignoring other noises in the system, atmosphere turbulence was the only cause for bit error rate.After solving the equation of laser transmission in atmospheric turbulence field, the relation between the system bit error rate,transmission range and space of atmospheric channels was obtained under the condition of the different number of transmitting antenna and correlation coefficients.The result indicated; under the weak fluctuation condition, the system bit error rate reduces quickly while increasing the number of transmitting antenna or decreasing the correlation coefficient or increasing the space between atmospheric channels; the system bit error rate increases while the turbulence intensity enhances; the system bit error rate reduces while the wavelength of transmission laser increases.When the transmitting antenna number is definite, system bit error rate will reduce with the space of atmospheric channels increasing.
The effect of the atmospheric turbulence on the bit error rate in a laser communication system with multiple beam transmission and reception was analyzed.Ignoring other noises in the system, atmosphere turbulence was the only cause for bit error rate.After solving the equation of laser transmission in atmospheric turbulence field, the relation between the system bit error rate,transmission range and space of atmospheric channels was obtained under the condition of the different number of transmitting antenna and correlation coefficients.The result indicated; under the weak fluctuation condition, the system bit error rate reduces quickly while increasing the number of transmitting antenna or decreasing the correlation coefficient or increasing the space between atmospheric channels; the system bit error rate increases while the turbulence intensity enhances; the system bit error rate reduces while the wavelength of transmission laser increases.When the transmitting antenna number is definite, system bit error rate will reduce with the space of atmospheric channels increasing.
2010, 34(2): 265-267,271.
doi: 10.3969/j.issn.1001-3806.2010.02.033
Abstract:
In order to get a compact watt-level high peak power UV laser, a compact plane-plane linear cavity, LD end pumped acoustic-optic Q-switched configuration was used. from which 1.03W-6.1W 1064nm IR laser at 1 kHz-50kHz repetition rate was obtained. With a LBO crystal employed to generate the second and third harmonic wave, the maximum output power of 1.08W UV at 10kHz repetition rate was achieved with peak power up to 12kW.The maximum peak power of UV laser was 17kW at 5kHz.The resules show that the practical application was satisfied in many fields.
In order to get a compact watt-level high peak power UV laser, a compact plane-plane linear cavity, LD end pumped acoustic-optic Q-switched configuration was used. from which 1.03W-6.1W 1064nm IR laser at 1 kHz-50kHz repetition rate was obtained. With a LBO crystal employed to generate the second and third harmonic wave, the maximum output power of 1.08W UV at 10kHz repetition rate was achieved with peak power up to 12kW.The maximum peak power of UV laser was 17kW at 5kHz.The resules show that the practical application was satisfied in many fields.
2010, 34(2): 272-274,284.
doi: 10.3969/j.issn.1001-3806.2010.02.035
Abstract:
In order to study self-focusing phenomenon of an intense short laser beam propagating in cold, underdense plasma,the more complete ponderomotive force of laser beam propagating with implicate term and Lorenz term was used.Calculation show that the implicate term has stronger nonlinear effect on self-focusing.Meanwhile the relativistic effect should be considered when laser pulse becomes strong enough.Although the consideration of relativistic effect makes the system nonlinearity larger,it could decrease the nonlinear effect on self-focusing.This is different from the relativistic self-focusing of long laser pulse.
In order to study self-focusing phenomenon of an intense short laser beam propagating in cold, underdense plasma,the more complete ponderomotive force of laser beam propagating with implicate term and Lorenz term was used.Calculation show that the implicate term has stronger nonlinear effect on self-focusing.Meanwhile the relativistic effect should be considered when laser pulse becomes strong enough.Although the consideration of relativistic effect makes the system nonlinearity larger,it could decrease the nonlinear effect on self-focusing.This is different from the relativistic self-focusing of long laser pulse.
2010, 34(2): 275-278.
doi: 10.3969/j.issn.1001-3806.2010.02.036
Abstract:
In order to study transmission characteristics of Lorentz pulses in a single-mode optical fiber, nonlinear Schrodinger equation was established from the Maxwell equation.The evolution equations for the parameters of the Lorentz pulses in single-mode optical fibers were derived by means of variational method from the modified nonlinear Schrödinger equation.Then,the restricted relations were obtained between amplitude and width, width and chirp.Analytical solution about the.width of pulse evolving on the propagation distance was obtained. The graph of the pulse width with the evolution of the transmission distance was described.The results show pulse width and the amplitude satisfy the adiabatic relation, the initial chirps will have an impact on the conformal transmission of Lorentz pulses.
In order to study transmission characteristics of Lorentz pulses in a single-mode optical fiber, nonlinear Schrodinger equation was established from the Maxwell equation.The evolution equations for the parameters of the Lorentz pulses in single-mode optical fibers were derived by means of variational method from the modified nonlinear Schrödinger equation.Then,the restricted relations were obtained between amplitude and width, width and chirp.Analytical solution about the.width of pulse evolving on the propagation distance was obtained. The graph of the pulse width with the evolution of the transmission distance was described.The results show pulse width and the amplitude satisfy the adiabatic relation, the initial chirps will have an impact on the conformal transmission of Lorentz pulses.
2010, 34(2): 285-288.
doi: 10.3969/j.issn.1001-3806.2010.02.039
Abstract:
In order to improve the stability and intelligence of a fast axial flow (FAF) CO2 laser, a control system was developed with a SIEMENS S7-200 programmable logic controller adopted as the core and with laser power stabilized based on sampling the light from the rear mirror of the laser resonator.The structure and principle of each unit were described.The system was tested on a 4kW FAF CO2 laser.The curves of pressure stability, power stability, discharge wave, and the pattern of laser mode were acquired. The pressure fluctuation was less than ±50Pa, the power fluctuation was close to 10.1%.The continuous, pulsed and hyper-pulsed discharge could be achieved.The results show that the system can control a FAF CO2 laser well and its stability and intelligence are improved.
In order to improve the stability and intelligence of a fast axial flow (FAF) CO2 laser, a control system was developed with a SIEMENS S7-200 programmable logic controller adopted as the core and with laser power stabilized based on sampling the light from the rear mirror of the laser resonator.The structure and principle of each unit were described.The system was tested on a 4kW FAF CO2 laser.The curves of pressure stability, power stability, discharge wave, and the pattern of laser mode were acquired. The pressure fluctuation was less than ±50Pa, the power fluctuation was close to 10.1%.The continuous, pulsed and hyper-pulsed discharge could be achieved.The results show that the system can control a FAF CO2 laser well and its stability and intelligence are improved.
2010, 34(2): 214-217.
doi: 10.3969/j.issn.1001-3806.2010.02.019
Abstract:
In order to obtain symmetry and parallel polarized light, the double Wollaston prism is amended. After getting symmetric polarized light at a big splitting beam angle, an ordinary triangular prism is added so that the symmetric light beam can be divided into parallel light beams.The distance between the triangular prism and the double Wollaston prism is changed so that the distance of the shearing parallel light can be changed.The measured transmittance of the new beam splitter is about 85% with measurement error of about 0.91 %.It saves material and saves the measurement time. It is able to meet the needs of more sophisticated measurement.
In order to obtain symmetry and parallel polarized light, the double Wollaston prism is amended. After getting symmetric polarized light at a big splitting beam angle, an ordinary triangular prism is added so that the symmetric light beam can be divided into parallel light beams.The distance between the triangular prism and the double Wollaston prism is changed so that the distance of the shearing parallel light can be changed.The measured transmittance of the new beam splitter is about 85% with measurement error of about 0.91 %.It saves material and saves the measurement time. It is able to meet the needs of more sophisticated measurement.
2010, 34(2): 232-235.
doi: 10.3969/j.issn.1001-3806.2010.02.024
Abstract:
With the help of the transmission matrix, the optical transmission property of 1-D photonic crystal containing negative refraction material with impurity defects was studied. There are two methods,insertion and substitution, to introduce defects into the arranged photonic crystal, and defect modes should happen.The defect modes resulted from negative defect often appears in the omni-directional photonic band gap, while those resulted from positive defect usually appears in the Bragg gap.The effect of doped method,incident direction, the thickness, defect location and defect type on the defect modes was studied.After analyzing two-defect-layer photonic crystal, the relation between the distance of both the layers and the band gap was found, i.e.,the nearer the defect layers, the easier and deeper the defect modes generated.The conclusions are useful for making the new type omni-directional filters.
With the help of the transmission matrix, the optical transmission property of 1-D photonic crystal containing negative refraction material with impurity defects was studied. There are two methods,insertion and substitution, to introduce defects into the arranged photonic crystal, and defect modes should happen.The defect modes resulted from negative defect often appears in the omni-directional photonic band gap, while those resulted from positive defect usually appears in the Bragg gap.The effect of doped method,incident direction, the thickness, defect location and defect type on the defect modes was studied.After analyzing two-defect-layer photonic crystal, the relation between the distance of both the layers and the band gap was found, i.e.,the nearer the defect layers, the easier and deeper the defect modes generated.The conclusions are useful for making the new type omni-directional filters.
2010, 34(2): 243-246.
doi: 10.3969/j.issn.1001-3806.2010.02.027
Abstract:
The square lattice of isotropic dielectric cylinders in air can not bring about the absolute band gap and the triangular lattice of dielectric cylinders can produce small absolute band gap.In order to get the bigger band gap,the anisotropic material is used instead of the isotropic material, for it can bring about big absolute band gap because of the dielectric constants of the anisotropic material are different in some directions. Based on plane wave method, calculation results show that the width of the absolute band gap for the square lattice is 0.03095ωe. For the triangular lattice the width is 0.03831ωe,which is 3.6 times wider than the absolute band gap produced by the isotropic dielectric cylinders.It is very useful for research of the band gap of photonic crystal.
The square lattice of isotropic dielectric cylinders in air can not bring about the absolute band gap and the triangular lattice of dielectric cylinders can produce small absolute band gap.In order to get the bigger band gap,the anisotropic material is used instead of the isotropic material, for it can bring about big absolute band gap because of the dielectric constants of the anisotropic material are different in some directions. Based on plane wave method, calculation results show that the width of the absolute band gap for the square lattice is 0.03095ωe. For the triangular lattice the width is 0.03831ωe,which is 3.6 times wider than the absolute band gap produced by the isotropic dielectric cylinders.It is very useful for research of the band gap of photonic crystal.
2010, 34(2): 268-271.
doi: 10.3969/j.issn.1001-3806.2010.02.034
Abstract:
In order to acquire the refractive index distribution of a square self-focusing lens, a semi-empirical method was put forward.The diffusion equation's solution under the square boundary conditions was approximated by the solution under the circular boundary conditions. The four unknown coefficients of the approximate solution were acquired by the known refractive index of the square self-focusing lens, and the refractive index was obtained by Jamin interference. This method avoids the complex process of solving the diffusion equation under the square boundary conditions, and the obtained semi-empirical formula is very simple and easy calculation.The calculation result agrees well with the experimental data, the maximal relative error is 0.94%,and the average is less than 0.3%,this formula provides a basis for the theoretical analysis of imaging of the square self-mixing lenses arrays.
In order to acquire the refractive index distribution of a square self-focusing lens, a semi-empirical method was put forward.The diffusion equation's solution under the square boundary conditions was approximated by the solution under the circular boundary conditions. The four unknown coefficients of the approximate solution were acquired by the known refractive index of the square self-focusing lens, and the refractive index was obtained by Jamin interference. This method avoids the complex process of solving the diffusion equation under the square boundary conditions, and the obtained semi-empirical formula is very simple and easy calculation.The calculation result agrees well with the experimental data, the maximal relative error is 0.94%,and the average is less than 0.3%,this formula provides a basis for the theoretical analysis of imaging of the square self-mixing lenses arrays.
2010, 34(2): 279-281.
doi: 10.3969/j.issn.1001-3806.2010.02.037
Abstract:
In order to study the polarization property of 1-D photonic crystal,transfer matrix method was used for calculation.It is found that at normal incidence, the change of the refractive index and the refractive index modulation will not influence the gap position and the gap for p light is coincident with that for s light; however, the lager the refractive index, the smaller the gap; the lager the modulation of the refractive indeed, the larger the gap.At oblique incidence,with the increase of the modulation of refraction index, the gap position moves to lower frequency and the gap becomes larger; with the increase of the refraction index, the gap position moves to lower frequency and the gap becomes smaller, especially the gap for s light becomes smaller obviously.The change of the thickness of the media down't influence the position of the gap of the two different polarizations.The conclusion is useful for the design of 1-D photonic photonic crystal polarizers.
In order to study the polarization property of 1-D photonic crystal,transfer matrix method was used for calculation.It is found that at normal incidence, the change of the refractive index and the refractive index modulation will not influence the gap position and the gap for p light is coincident with that for s light; however, the lager the refractive index, the smaller the gap; the lager the modulation of the refractive indeed, the larger the gap.At oblique incidence,with the increase of the modulation of refraction index, the gap position moves to lower frequency and the gap becomes larger; with the increase of the refraction index, the gap position moves to lower frequency and the gap becomes smaller, especially the gap for s light becomes smaller obviously.The change of the thickness of the media down't influence the position of the gap of the two different polarizations.The conclusion is useful for the design of 1-D photonic photonic crystal polarizers.
2010, 34(2): 282-284.
doi: 10.3969/j.issn.1001-3806.2010.02.038
Abstract:
In order to study Jones matrix of a phase retarder, a unified expression of the Jones matrix was got by means of theoretical derivation and analysis,and some Jones matrices in some literature was revised and explained.For a λ/n wave-plate, the effect of the phase retardation on Jones matrix was analyzed and verified with the methods of theoretical analysis and experimental verification.The results show that thickness of the wave-plate and material property have the same effect on the linearly polarized light, but have different effect on Jones matrix are different. When the fast-axis is at an angle of θ with x-axis, only the former affects Jones matrix.
In order to study Jones matrix of a phase retarder, a unified expression of the Jones matrix was got by means of theoretical derivation and analysis,and some Jones matrices in some literature was revised and explained.For a λ/n wave-plate, the effect of the phase retardation on Jones matrix was analyzed and verified with the methods of theoretical analysis and experimental verification.The results show that thickness of the wave-plate and material property have the same effect on the linearly polarized light, but have different effect on Jones matrix are different. When the fast-axis is at an angle of θ with x-axis, only the former affects Jones matrix.
