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RSS2005 Vol. 29, No. 4
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2005, 29(4): 337-339.
[Abstract]
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Abstract:
Approximate condition of reflectivity measurement with cavity ring-down method is analyzed,misadjustment characteristic of confocal cavity is discussed and influence of cavity mirror's reflectivity on ring-down signal is calculated.In order to lessen metrical precision from diffraction losses of OPO laser,based on the above analyses,a reflectivity measuring system for single wavelength is set up with cavity ring-down method,whose ring-down cavity is confocal cavity.Experimental measurement of reflectivity of cavity mirror and inserted mirror is carried out.The measurement RMS in linear cavity is less than 6×10-6.Results show that cavity ring-down method is only for higher reflectivity,and metrical precision can be improved by using logarithm transform of oscillograph in adjustment of the optical cavity.
Approximate condition of reflectivity measurement with cavity ring-down method is analyzed,misadjustment characteristic of confocal cavity is discussed and influence of cavity mirror's reflectivity on ring-down signal is calculated.In order to lessen metrical precision from diffraction losses of OPO laser,based on the above analyses,a reflectivity measuring system for single wavelength is set up with cavity ring-down method,whose ring-down cavity is confocal cavity.Experimental measurement of reflectivity of cavity mirror and inserted mirror is carried out.The measurement RMS in linear cavity is less than 6×10-6.Results show that cavity ring-down method is only for higher reflectivity,and metrical precision can be improved by using logarithm transform of oscillograph in adjustment of the optical cavity.
2005, 29(4): 340-342,346.
Abstract:
The results of experimental study on a complex cavity Nd:YAG laser pumped LiNbO3 crystal optical parametric oscillator(OPO) is reported.Average output pulse energies of 56.4mJ of the OPO and 22.8mJ of the idler at 3097nm were observed with the pulse width of 8ns.The conversion efficiency from 1060nm pumping laser to the OPO output (the signal and idler) was 46% at pulse repetition rates up to 10Hz.The tuning ranges of the OPO obtained by angle tuning the LiNbO3 crystal were 1479nm～1621nm of the signal,and 3097nm～3793nm of the idler.
The results of experimental study on a complex cavity Nd:YAG laser pumped LiNbO3 crystal optical parametric oscillator(OPO) is reported.Average output pulse energies of 56.4mJ of the OPO and 22.8mJ of the idler at 3097nm were observed with the pulse width of 8ns.The conversion efficiency from 1060nm pumping laser to the OPO output (the signal and idler) was 46% at pulse repetition rates up to 10Hz.The tuning ranges of the OPO obtained by angle tuning the LiNbO3 crystal were 1479nm～1621nm of the signal,and 3097nm～3793nm of the idler.
2005, 29(4): 343-346.
Abstract:
Taking into account temperature-dependent thermal conduction and heat capacity,a three-dimensional transient finite element model was established.A sequentially analysis of coupled thermal-stress was employed.Some conclusions related to the simulation results are made:maximum thermal stress lessens with sintering going on owing to effect of sintered region;the region ahead of sintering has greater stress distribution than behind.
Taking into account temperature-dependent thermal conduction and heat capacity,a three-dimensional transient finite element model was established.A sequentially analysis of coupled thermal-stress was employed.Some conclusions related to the simulation results are made:maximum thermal stress lessens with sintering going on owing to effect of sintered region;the region ahead of sintering has greater stress distribution than behind.
2005, 29(4): 347-349,353.
Abstract:
The properties of Nd:glass rod lasers in the heat capacity operation,including the temperature and stress distributions,are simulated and compared with the conventional pumping and cooling scheme.It is shown that the heat capacity based lasers have the noticeable advantage over conventional lasers if very higi output energy within a short time is required.
The properties of Nd:glass rod lasers in the heat capacity operation,including the temperature and stress distributions,are simulated and compared with the conventional pumping and cooling scheme.It is shown that the heat capacity based lasers have the noticeable advantage over conventional lasers if very higi output energy within a short time is required.
2005, 29(4): 350-353.
Abstract:
The temperature raise of KTP crystal with intracavity doubling frequency would greatly influence the performance and characteristic of the LD pumped all-solid-state green laser.In order to improve performance of laser,interior temperature field distribution of KTP crystal must be accurately controlled.Through completely work feature analysis of KTP crystal in the (Nd:YVO4/KTP) green laser,the thermal model according to the practicality is built,the general solution of a quadrate KTP crystal interior temperature distribution is obtained by an analytical thermal analysis method.As the quadrate thermal model is almost identical with laser,the deduced results will be more reasonable.The research results express that the KTP crystal maximal temperature raise according to the quadrate thermal mode is higher than the maximal temperature raise with the cylindrical thermal mode.The research provides a theoretical foundation for phase mismatching induced by non-uniform temperature raise,and play instructive effect in the improvement the performance of the Nd:YVO4/KTP green laser.
The temperature raise of KTP crystal with intracavity doubling frequency would greatly influence the performance and characteristic of the LD pumped all-solid-state green laser.In order to improve performance of laser,interior temperature field distribution of KTP crystal must be accurately controlled.Through completely work feature analysis of KTP crystal in the (Nd:YVO4/KTP) green laser,the thermal model according to the practicality is built,the general solution of a quadrate KTP crystal interior temperature distribution is obtained by an analytical thermal analysis method.As the quadrate thermal model is almost identical with laser,the deduced results will be more reasonable.The research results express that the KTP crystal maximal temperature raise according to the quadrate thermal mode is higher than the maximal temperature raise with the cylindrical thermal mode.The research provides a theoretical foundation for phase mismatching induced by non-uniform temperature raise,and play instructive effect in the improvement the performance of the Nd:YVO4/KTP green laser.
2005, 29(4): 354-357,372.
Abstract:
The soliton source is the key element in the soliton communication system.In order to search the satisfying soliton source in the low loss fiber of the soliton communication,the disturbed nonlinear Schrdinger equation of the ultrashort optical pulses was derived in response to the property of pulse in the Cr4+:YAG laser,the influence of dispersion and gain and loss and nonlinear effect on the fundamental soliton was analysed in the cavity in system,the relation between the configuration of the cavity and the parameters of the fundamental soliton was discussed.It is proved that the generation of the fundamental soliton in the Cr4+:YAG laser,and the Cr4+:YAG laser may be the soliton source of the soliton communication system.
The soliton source is the key element in the soliton communication system.In order to search the satisfying soliton source in the low loss fiber of the soliton communication,the disturbed nonlinear Schrdinger equation of the ultrashort optical pulses was derived in response to the property of pulse in the Cr4+:YAG laser,the influence of dispersion and gain and loss and nonlinear effect on the fundamental soliton was analysed in the cavity in system,the relation between the configuration of the cavity and the parameters of the fundamental soliton was discussed.It is proved that the generation of the fundamental soliton in the Cr4+:YAG laser,and the Cr4+:YAG laser may be the soliton source of the soliton communication system.
2005, 29(4): 358-360,376.
Abstract:
A new multilayer blazed reflective grating is shown.Using thin-film technology,the blazed reflective grating's diffraction property and reflectivity property have been improved greatly.Making use of these properties,the gain narrowing in femtosecond lasers is restrained.The calculation result and experiment result show that using this new grating to broaden seed pulse has many advantages:the loss of seed pulse energy is less,the efficiency of broadening is high,the gain narrowing is attenuated much.Furthermore it can make experiment easier and convenient for integration.
A new multilayer blazed reflective grating is shown.Using thin-film technology,the blazed reflective grating's diffraction property and reflectivity property have been improved greatly.Making use of these properties,the gain narrowing in femtosecond lasers is restrained.The calculation result and experiment result show that using this new grating to broaden seed pulse has many advantages:the loss of seed pulse energy is less,the efficiency of broadening is high,the gain narrowing is attenuated much.Furthermore it can make experiment easier and convenient for integration.
2005, 29(4): 361-363,394.
Abstract:
Several important factors(length of fiber grating,coupling coefficient,reflectivity of internal cavity) which strongly affects the characteristics of fiber grating external cavity semiconductor lasers are analyzed.The analytical theory is confirmed by the following numerical simulations and experimental results.Then the spectrums of FBG-ECL with different reflectivity of fiber gratings are examinated and the perfect spectrum with 0.1nm of bandwidth,power of 417.4μW,37.9dB of side-mode suppression ratio are got.The results demonstrate that theoretical analysis,numerical simulations are in agreement with the experimental observations.
Several important factors(length of fiber grating,coupling coefficient,reflectivity of internal cavity) which strongly affects the characteristics of fiber grating external cavity semiconductor lasers are analyzed.The analytical theory is confirmed by the following numerical simulations and experimental results.Then the spectrums of FBG-ECL with different reflectivity of fiber gratings are examinated and the perfect spectrum with 0.1nm of bandwidth,power of 417.4μW,37.9dB of side-mode suppression ratio are got.The results demonstrate that theoretical analysis,numerical simulations are in agreement with the experimental observations.
2005, 29(4): 364-365,369.
Abstract:
High power up to 13.13mW(11.18dBm)of L-band SFS is developed and obtained,the mean wavelength is 1578.53nm,by using configuration of double-pass and highly doped erbium fiber,the power between 1570nm and 1620nm is higher than 9.38mW.It is important for many applicants such as distributed fiber grating sensing,fiber-optic gyroscope,DWDM,which expand from C-band to L-band.Combined with C-band,simultaneous output of C+L band with power of higher than 20mW.Hereinto,a fiber loop reflector made from normal coupler is used to injection the C-band amplified spontaneous emission of backward again enhanced the efficiency of LD and stability of output of fiber.Meanwhile,effects of fiber length and pump power on output,mean wavelength,stability is analysed,it is valuable to the design of SFS.
High power up to 13.13mW(11.18dBm)of L-band SFS is developed and obtained,the mean wavelength is 1578.53nm,by using configuration of double-pass and highly doped erbium fiber,the power between 1570nm and 1620nm is higher than 9.38mW.It is important for many applicants such as distributed fiber grating sensing,fiber-optic gyroscope,DWDM,which expand from C-band to L-band.Combined with C-band,simultaneous output of C+L band with power of higher than 20mW.Hereinto,a fiber loop reflector made from normal coupler is used to injection the C-band amplified spontaneous emission of backward again enhanced the efficiency of LD and stability of output of fiber.Meanwhile,effects of fiber length and pump power on output,mean wavelength,stability is analysed,it is valuable to the design of SFS.
2005, 29(4): 366-369.
Abstract:
Based on the passive robot,a 3-D laser scanning system is put forward,the principle of the system is introduced.The 3-D coordinates are derived according to double-trigonometry method.The self-learning algorithm of the network based on generalization ability has been developed to calibrate the 3-D laser scanner.A teacup cover is scanned with the measuring system.The measuring precision is less than 0.1mm.Experimental results prove the effectiveness of the measuring principle and the reliability of this measuring system.
Based on the passive robot,a 3-D laser scanning system is put forward,the principle of the system is introduced.The 3-D coordinates are derived according to double-trigonometry method.The self-learning algorithm of the network based on generalization ability has been developed to calibrate the 3-D laser scanner.A teacup cover is scanned with the measuring system.The measuring precision is less than 0.1mm.Experimental results prove the effectiveness of the measuring principle and the reliability of this measuring system.
2005, 29(4): 370-372.
Abstract:
It is unavoidable that the hardness in the laser scanning area is not uniform due to the laser overlapping.Furthermore,the crack is apt to appear in the overlapping area.Firstly,the varying principles of the thermal cycle and stress during the laser scanning can be explained through the numerical methods.As a result,the theoretical explanations of the formation of the tempering and second quenching area are shown.The simulation results indicate that different overlapping parameters have little influence on the temperature varying principles.On the other hand,the parameters should not set too large in order to reduce the ununiformity of the hardness and crack in the area.
It is unavoidable that the hardness in the laser scanning area is not uniform due to the laser overlapping.Furthermore,the crack is apt to appear in the overlapping area.Firstly,the varying principles of the thermal cycle and stress during the laser scanning can be explained through the numerical methods.As a result,the theoretical explanations of the formation of the tempering and second quenching area are shown.The simulation results indicate that different overlapping parameters have little influence on the temperature varying principles.On the other hand,the parameters should not set too large in order to reduce the ununiformity of the hardness and crack in the area.
2005, 29(4): 373-376.
Abstract:
The status and prospect in domestic and oversea area of conductive line fabrication by laser technology is reviewed.Compared with its conditional methods,the basic characteristics and advantages are presented.What's more,the development trend of this technology is predicted and some suggestions are put forward for its future development.
The status and prospect in domestic and oversea area of conductive line fabrication by laser technology is reviewed.Compared with its conditional methods,the basic characteristics and advantages are presented.What's more,the development trend of this technology is predicted and some suggestions are put forward for its future development.
Research of gain of vertical cavity semiconductor optical amplifiers based on transfer matrix method
2005, 29(4): 377-379,406.
Abstract:
The gain and bandwidth of vertical cavity semiconductor optical amplifiers (VCSOAs) were studied based on transfer matrix method.The different carrier density and layers number of DBR will affect the gain characteristic and the wavelength of the peak gain will shift with the variation of position of the quantum well stacks in active region.The result of calculation is agreement with the experiment.
The gain and bandwidth of vertical cavity semiconductor optical amplifiers (VCSOAs) were studied based on transfer matrix method.The different carrier density and layers number of DBR will affect the gain characteristic and the wavelength of the peak gain will shift with the variation of position of the quantum well stacks in active region.The result of calculation is agreement with the experiment.
2005, 29(4): 380-382.
Abstract:
According to the Huygens-Fresnel principle,Debye formula is revised.By using the revised Debye formula the diffraction of a converging spherical wave at a circular aperture is studied and the results are compared in detail with those obtained by using the Li-Wolf formula and original Debye formula.It is shown that the revised Debye formula is still valid for the low Fresnel number near the geometric focus and can give focal shift that can not be predicted in the use of the Debye formula.
According to the Huygens-Fresnel principle,Debye formula is revised.By using the revised Debye formula the diffraction of a converging spherical wave at a circular aperture is studied and the results are compared in detail with those obtained by using the Li-Wolf formula and original Debye formula.It is shown that the revised Debye formula is still valid for the low Fresnel number near the geometric focus and can give focal shift that can not be predicted in the use of the Debye formula.
2005, 29(4): 383-385.
Abstract:
The physical and chemical processes about CO2 laser-induced deposition of metal Ag from aqueous solution were studied.The process of metal deposition along horizontal and longitudinal orientation were discussed.It is concluded that the Ag granules deoxidized in solution infiltrate into substrate while depositing on surface of substrate.
The physical and chemical processes about CO2 laser-induced deposition of metal Ag from aqueous solution were studied.The process of metal deposition along horizontal and longitudinal orientation were discussed.It is concluded that the Ag granules deoxidized in solution infiltrate into substrate while depositing on surface of substrate.
2005, 29(4): 386-388,428.
Abstract:
The transient temperature fields generated by a pulsed laser in cylindrical shell were obtained by using the finite element method (FEM).The temperature dependences of material properties were taken into account during the numerical simulation.The temperature distributions of aluminum pipe were obtained in radial orientation and angular orientation at various time.The pulsed laser induced transient temperature fields were obtained in aluminum pipe,which would be useful in the research on thermo-elastic excitation of laser ultrasonic waves in cylindrical shell.
The transient temperature fields generated by a pulsed laser in cylindrical shell were obtained by using the finite element method (FEM).The temperature dependences of material properties were taken into account during the numerical simulation.The temperature distributions of aluminum pipe were obtained in radial orientation and angular orientation at various time.The pulsed laser induced transient temperature fields were obtained in aluminum pipe,which would be useful in the research on thermo-elastic excitation of laser ultrasonic waves in cylindrical shell.
2005, 29(4): 389-391.
Abstract:
The output energy of a pulsed TEA CO2 laser versus the ambient temperature -30℃～+60℃ was calculated out by six-temperature mode rate equations.Numerical result shows that the output pulse energy almost decreases linearly with the ambient temperature.The gradient of the pulse energy to ambient temperature varies with the composition of the laser mixtures,pressure,mirror reflectance or input energy.With higher mixture pressure,mirror reflectance,or input energy,the output pulse energy decreases more quickly with the ambient temperature.
The output energy of a pulsed TEA CO2 laser versus the ambient temperature -30℃～+60℃ was calculated out by six-temperature mode rate equations.Numerical result shows that the output pulse energy almost decreases linearly with the ambient temperature.The gradient of the pulse energy to ambient temperature varies with the composition of the laser mixtures,pressure,mirror reflectance or input energy.With higher mixture pressure,mirror reflectance,or input energy,the output pulse energy decreases more quickly with the ambient temperature.
2005, 29(4): 392-394.
Abstract:
Based on the threat mechanism and damage treshold of laser to human eyes,a design project and the qualification of a laser dissuader were put forward;its ingridients and arrangement were studied respectively;and the parameters of the dissuader were analyzed by computer and given at last.This investigation is useful for producing practical equipments in the future.
Based on the threat mechanism and damage treshold of laser to human eyes,a design project and the qualification of a laser dissuader were put forward;its ingridients and arrangement were studied respectively;and the parameters of the dissuader were analyzed by computer and given at last.This investigation is useful for producing practical equipments in the future.
2005, 29(4): 395-397.
Abstract:
To observe the effect of hypericin-mediated photodynamic therapy on apoptosis of human nasopharyngeal carcinoma cells,the apoptotic and secondary necrotic rate of the nasopharyageal carcinoma(NPC) CNE2 cells induced by hypericin-mediated photodynamic therapy was determined by flow cytometry with Annexin V-PI staining.The apoptotic and secondary necrotic rate of the NPC CNE2 cells after photodynamic therapy significantly increased to 53.08% and 6.77%,and they were higher than those of the controls respectively (P< 0.01),but there was no significance of the apoptotic and secondary necrotic rate between the controls (P> 0.05).Hypericin-mediated photodynamic therapy might obviously trigger the NPC CNE2 cells into apoptosis,which might be one of the mechanisms of hypericin-mediated photodynamic therapy on nasopharyngeal carcinoma.
To observe the effect of hypericin-mediated photodynamic therapy on apoptosis of human nasopharyngeal carcinoma cells,the apoptotic and secondary necrotic rate of the nasopharyageal carcinoma(NPC) CNE2 cells induced by hypericin-mediated photodynamic therapy was determined by flow cytometry with Annexin V-PI staining.The apoptotic and secondary necrotic rate of the NPC CNE2 cells after photodynamic therapy significantly increased to 53.08% and 6.77%,and they were higher than those of the controls respectively (P< 0.01),but there was no significance of the apoptotic and secondary necrotic rate between the controls (P> 0.05).Hypericin-mediated photodynamic therapy might obviously trigger the NPC CNE2 cells into apoptosis,which might be one of the mechanisms of hypericin-mediated photodynamic therapy on nasopharyngeal carcinoma.
2005, 29(4): 398-400,422.
Abstract:
The beam sampling grating(BSG) used in the inertial confinement fusion system is designed.By means of optical holographic theory,achromatic optical system recording holographic BSG mask is designed.Its aberration is analyzed with ZEMAX.Meantime,the diffraction efficiency of the BSG is discussed based on rigorous coupled-wave theory.The results show:the groove depth is more important for diffraction efficiency than the duty cycle,which is useful for fabrication of the BSG.
The beam sampling grating(BSG) used in the inertial confinement fusion system is designed.By means of optical holographic theory,achromatic optical system recording holographic BSG mask is designed.Its aberration is analyzed with ZEMAX.Meantime,the diffraction efficiency of the BSG is discussed based on rigorous coupled-wave theory.The results show:the groove depth is more important for diffraction efficiency than the duty cycle,which is useful for fabrication of the BSG.
2005, 29(4): 401-403,436.
Abstract:
The Fourier transform characteristics of off-axis hololens was discussed,which was made by using a dot light source and an inclined parallel light.The Fourier transform power spectrum of input object can be obtained when the input image is placed at the front or back of the hololens.The more small the size of input image is and long the focal length is,the more small the error is.The exact Fourier transform of the object can be obtained when it is placed at the front focal plane of the hololens.At the end of this paper,the optical experimental results are given.
The Fourier transform characteristics of off-axis hololens was discussed,which was made by using a dot light source and an inclined parallel light.The Fourier transform power spectrum of input object can be obtained when the input image is placed at the front or back of the hololens.The more small the size of input image is and long the focal length is,the more small the error is.The exact Fourier transform of the object can be obtained when it is placed at the front focal plane of the hololens.At the end of this paper,the optical experimental results are given.
2005, 29(4): 404-406.
Abstract:
The numerical calculation of the diode side-pumped solid-state laser and the software used to trace the rays refracted into the solid-state laser rod are introduced in detail.The graph in the cross-section of the laser rod is drawn according to distributions of each ray.From the graph,it can be seen that the intensity of the cross-section is uniform.The software is convenient and available.
The numerical calculation of the diode side-pumped solid-state laser and the software used to trace the rays refracted into the solid-state laser rod are introduced in detail.The graph in the cross-section of the laser rod is drawn according to distributions of each ray.From the graph,it can be seen that the intensity of the cross-section is uniform.The software is convenient and available.
2005, 29(4): 407-409,413.
Abstract:
Based on analyzing the phase and electric field characteristics of different combination of reflective mirrors in semiconductor lasers,the corresponding standing-wave patterns were studied carefully.The results show that the standing-wave pattern is closely related with the choice of the index of the top reflective mirror,and the overlapping position of the center of the active layer and the standing-wave greatly effects the confinement factor and the threshold characteristics of vertical-cavity surface-emitting lasers(VCSEL).
Based on analyzing the phase and electric field characteristics of different combination of reflective mirrors in semiconductor lasers,the corresponding standing-wave patterns were studied carefully.The results show that the standing-wave pattern is closely related with the choice of the index of the top reflective mirror,and the overlapping position of the center of the active layer and the standing-wave greatly effects the confinement factor and the threshold characteristics of vertical-cavity surface-emitting lasers(VCSEL).
2005, 29(4): 410-413.
Abstract:
An adaptive step-size method for the coupled equations of multi-pumped broadband Raman amplifiers was proposed based on Runge-Kutta-Fehlberg methods.This algorithm adjusts the step-size appropriately according to the presupposed precision and the local truncation error of each step.Simulation results indicate that our adaptive step-size method improves the accuracy and the simulating speed efficiently compared with other traditional algorithms and suits the numerical simulation for fiber Raman amplifier.
An adaptive step-size method for the coupled equations of multi-pumped broadband Raman amplifiers was proposed based on Runge-Kutta-Fehlberg methods.This algorithm adjusts the step-size appropriately according to the presupposed precision and the local truncation error of each step.Simulation results indicate that our adaptive step-size method improves the accuracy and the simulating speed efficiently compared with other traditional algorithms and suits the numerical simulation for fiber Raman amplifier.
2005, 29(4): 414-416.
Abstract:
The working principle of CCD and laser disturbing principle are introduced.After analyzing the laser transmission characteristics in atmosphere,laser output power needed to disturb satellite-based CCD is calculated,which should reach 109W.Finally some key technologies are put forward.
The working principle of CCD and laser disturbing principle are introduced.After analyzing the laser transmission characteristics in atmosphere,laser output power needed to disturb satellite-based CCD is calculated,which should reach 109W.Finally some key technologies are put forward.
2005, 29(4): 417-419,448.
Abstract:
The small scanning-spot excimer laser corneal system was developed based on flying-spot scanning model.The comparative experiment between PMMA and cornea was fulfilled as well as clinical animal and blind eyes experiments.The experimental results show that the excimer laser refractive system is characteristic of short cure time,high accuracy,surface smoothness and easy to integrate the wavefront aberration technology.
The small scanning-spot excimer laser corneal system was developed based on flying-spot scanning model.The comparative experiment between PMMA and cornea was fulfilled as well as clinical animal and blind eyes experiments.The experimental results show that the excimer laser refractive system is characteristic of short cure time,high accuracy,surface smoothness and easy to integrate the wavefront aberration technology.
2005, 29(4): 420-422.
Abstract:
Total attenuation coefficients of normal and cancerous human bladder tissue at 476.5nm,488nm,496.5nm,514.5nm,532nm and 808nm lasers and their linearly polarized laser were determined using the direct and indirect methods,and an integrating-sphere system.The results show that there are significant differences in these total attenuation coefficients of normal or cancerous human bladder tissue at six different wavelengths of laser between the direct and indirect methods(P< 0.05),the differences in the total attenuation coefficients of normal or cancerous human bladder tissue at six different wavelengths between the direct and indirect methods are all obviously bigger than the differences in the total attenuation coefficients of normal or cancerous human bladder tissue at their linearly polarized laser wavelengths between the direct and indirect methods (P< 0.05).
Total attenuation coefficients of normal and cancerous human bladder tissue at 476.5nm,488nm,496.5nm,514.5nm,532nm and 808nm lasers and their linearly polarized laser were determined using the direct and indirect methods,and an integrating-sphere system.The results show that there are significant differences in these total attenuation coefficients of normal or cancerous human bladder tissue at six different wavelengths of laser between the direct and indirect methods(P< 0.05),the differences in the total attenuation coefficients of normal or cancerous human bladder tissue at six different wavelengths between the direct and indirect methods are all obviously bigger than the differences in the total attenuation coefficients of normal or cancerous human bladder tissue at their linearly polarized laser wavelengths between the direct and indirect methods (P< 0.05).
2005, 29(4): 423-425.
Abstract:
The efficiency of dielectric reflection grating was calculated with C method theoretically.Characteristics of the photoresist grating mask were obtained from SEM pictures and the curves of grating efficiency were presented.The trend of these curves had some relationships with correspondent masks' characteristics.So,a nondestructive testing method with the characteristic spectrum of efficiency to estimate the groove of grating was put forward.It is concluded that this method is useful to determine whether the photoresist has been developed to the basement which is the key in manufacture technology of grating mask.
The efficiency of dielectric reflection grating was calculated with C method theoretically.Characteristics of the photoresist grating mask were obtained from SEM pictures and the curves of grating efficiency were presented.The trend of these curves had some relationships with correspondent masks' characteristics.So,a nondestructive testing method with the characteristic spectrum of efficiency to estimate the groove of grating was put forward.It is concluded that this method is useful to determine whether the photoresist has been developed to the basement which is the key in manufacture technology of grating mask.
2005, 29(4): 426-428.
Abstract:
It is known that usually the degree of sharpness (or flatness) of beam intensity distribution is described by the kurtosis parameter (K parameter).Taking cosh-Gaussian (ChG),Bessel-modulated Gaussian (QBG),and flattened Gaussian (FG) beams as three illustrative examples,detailed numerical calculations and physical interpretations were given.It is shown that the K parameter is suited essentially to characterize the sharpness of the bell-shape beam profile,but not applicable to beams with large diffraction sidelobes,large intensity modulations,and beams with central shadow.
It is known that usually the degree of sharpness (or flatness) of beam intensity distribution is described by the kurtosis parameter (K parameter).Taking cosh-Gaussian (ChG),Bessel-modulated Gaussian (QBG),and flattened Gaussian (FG) beams as three illustrative examples,detailed numerical calculations and physical interpretations were given.It is shown that the K parameter is suited essentially to characterize the sharpness of the bell-shape beam profile,but not applicable to beams with large diffraction sidelobes,large intensity modulations,and beams with central shadow.
2005, 29(4): 429-432.
Abstract:
It is important to study the pulse response characteristic of one-dimensional PSD and rules of output photocurrent under the condition of pulsed light irradiation in order to compute the incident position of pulsed light accurately.The function of the pulsed light is presented,and the pulse response characteristic of PSD is discussed in the case of four different modes of pulsed light,and the phenomenon of pulse pile up is also studied.The results show that if the irradiation time of the pulsed light is much greater than the response time,the incident position of pulsed light satisfies the conversion formula of one-dimensional PSD.When the irradiation time of light is less than the response time,as long as irradiation time is 2.5 times greater than the time response constant,the shorter time of stopping irradiation is,the more preferable linear relation between incident position and output currents of PSD is.
It is important to study the pulse response characteristic of one-dimensional PSD and rules of output photocurrent under the condition of pulsed light irradiation in order to compute the incident position of pulsed light accurately.The function of the pulsed light is presented,and the pulse response characteristic of PSD is discussed in the case of four different modes of pulsed light,and the phenomenon of pulse pile up is also studied.The results show that if the irradiation time of the pulsed light is much greater than the response time,the incident position of pulsed light satisfies the conversion formula of one-dimensional PSD.When the irradiation time of light is less than the response time,as long as irradiation time is 2.5 times greater than the time response constant,the shorter time of stopping irradiation is,the more preferable linear relation between incident position and output currents of PSD is.
2005, 29(4): 433-436.
Abstract:
Based on ray-tracing the transmitted and distributed ways of the beams of the semiconductor lasers were gained.The theory indicates how to select the main parameters in designing lens duct,to obtain the approximated Gaussian mode light from the output face.The theory showsthat high-power density beams can be obtained with lens duct in coupling high-power semiconductor lasers,and this coupling-method would be the main one in coupling-systems of the all solid-state lasers in the future.
Based on ray-tracing the transmitted and distributed ways of the beams of the semiconductor lasers were gained.The theory indicates how to select the main parameters in designing lens duct,to obtain the approximated Gaussian mode light from the output face.The theory showsthat high-power density beams can be obtained with lens duct in coupling high-power semiconductor lasers,and this coupling-method would be the main one in coupling-systems of the all solid-state lasers in the future.
2005, 29(4): 437-439.
Abstract:
By using the general diffraction integration method,the transformation property of Bessel-Gaussian(BG) beam in a fractional Fourier plane was studied,and closed-form transformation expression was derived for the BG beam through the LohmannⅡ optical system.By using the derived formula,typical numerical calculation results were obtained to study the influences of the fractional order on the properties of BG beam in the fractional Fourier plane.It is shown that the intensity of BG beam depends on the fractional order p and the variation of the intensity with fractional order p is periodic.
By using the general diffraction integration method,the transformation property of Bessel-Gaussian(BG) beam in a fractional Fourier plane was studied,and closed-form transformation expression was derived for the BG beam through the LohmannⅡ optical system.By using the derived formula,typical numerical calculation results were obtained to study the influences of the fractional order on the properties of BG beam in the fractional Fourier plane.It is shown that the intensity of BG beam depends on the fractional order p and the variation of the intensity with fractional order p is periodic.
2005, 29(4): 440-442,445.
Abstract:
SiO2 is formed on the monocrystalline silicon(100) substrate by means of high temperatare oxidation,then Yb and Er are embeded in highly pure aluminum,and Yb,Er-co-doped Al2O3 film is produced with middle frequeney sputter technique.The influence of target voltage and deposit rate varying with oxygen flow is discussed.The optimized oxygen flow of deposite oxide film is presented.A strong photoluminescence at 1535nm is detected at the room temperature.Optical film is carved by BCl3 ion beam under optical mask to form square optical waveguide.
SiO2 is formed on the monocrystalline silicon(100) substrate by means of high temperatare oxidation,then Yb and Er are embeded in highly pure aluminum,and Yb,Er-co-doped Al2O3 film is produced with middle frequeney sputter technique.The influence of target voltage and deposit rate varying with oxygen flow is discussed.The optimized oxygen flow of deposite oxide film is presented.A strong photoluminescence at 1535nm is detected at the room temperature.Optical film is carved by BCl3 ion beam under optical mask to form square optical waveguide.
2005, 29(4): 443-445.
Abstract:
Based on the angular spectrum representation and the theory of the second intensity moment of non-paraxial scalar beam,the beam waist radius,the far-field divergence angle and the beam quality factor of non-paraxial scalar sinh-Gaussian(ShG) beams were calculated.Compared with the beam quality factor of paraxial scalar sinh-Gaussian (ShG) beams,some new results were obtained.When the beam waist radius is relatively large,the theoretical calculations for the beam quality factor of paraxial and non-paraxial scalar sinh-Gaussian(ShG) beams change in the same way and the theory of the traditional second intensity moment of scalar light field is a valid approximation; when the beam waist radius is very small,they have a great difference and the theory of the second intensity moment of non-paraxial scalar beam must be used.
Based on the angular spectrum representation and the theory of the second intensity moment of non-paraxial scalar beam,the beam waist radius,the far-field divergence angle and the beam quality factor of non-paraxial scalar sinh-Gaussian(ShG) beams were calculated.Compared with the beam quality factor of paraxial scalar sinh-Gaussian (ShG) beams,some new results were obtained.When the beam waist radius is relatively large,the theoretical calculations for the beam quality factor of paraxial and non-paraxial scalar sinh-Gaussian(ShG) beams change in the same way and the theory of the traditional second intensity moment of scalar light field is a valid approximation; when the beam waist radius is very small,they have a great difference and the theory of the second intensity moment of non-paraxial scalar beam must be used.
2005, 29(4): 446-448.
Abstract:
According to the traditional pulse coding laser's technology status that its pulse repeating frequency coding can be easily in terfered,a new idea of laser pulse width coding was put forward applying pulse width tuning laser.For this reason,a kind of pulse width tuning laser realization project applying frequent electro-optic chopping wave technology was put forward.This kind of pulse coding laser was made up of seed laser,electro-optic chopping wave groupware and laser amplifier.The programm able controller was used to control the retard circuits to alter the electric pulse width on the pole of the Pocke ls cell, and then the output laser pulse could be tuned.The academic design of this pulse coding laser and its expermiental system were finished.The prmiary analysis approves the feasibility o f the project.
According to the traditional pulse coding laser's technology status that its pulse repeating frequency coding can be easily in terfered,a new idea of laser pulse width coding was put forward applying pulse width tuning laser.For this reason,a kind of pulse width tuning laser realization project applying frequent electro-optic chopping wave technology was put forward.This kind of pulse coding laser was made up of seed laser,electro-optic chopping wave groupware and laser amplifier.The programm able controller was used to control the retard circuits to alter the electric pulse width on the pole of the Pocke ls cell, and then the output laser pulse could be tuned.The academic design of this pulse coding laser and its expermiental system were finished.The prmiary analysis approves the feasibility o f the project.
