Numerical simulation of Otto structure in surface plasma wave light modulator

On the foundation of frustrated total internal reflect ion (FTIR) light modulator,combining the character of surface plasma wave (SPW) which is excitated on the surface of metal and can be resonant with ppolari zation light and absorbs its energy,a modified type SPW light modulator of Otto structure is designed.In Otto structure,the reflectivity can be modulated by changing thickness of air gap or the angle of incidence.The numerical simulation is made in the situation of three kinds of metal:Cu,Al,Ag and two wavelengths:1.06 4μm,0.532μm,and the results show that modulate effect of the method of changi ng angle of incidence is better,0.5°of the angle change can result in reflectivity's variety value is above 0.9.