耦合角度对平面波导叠加型光栅解波分复用性能的影响

The Influence of Coupling Angle to the Characteristics of Wavelength-division Demultiplexer Based on Planar Waveguide Supergratings

利用玻璃材料的光敏性可在平面波导中制作出具有解波分复用功能的叠加型光栅,根据耦合模理论对这种平面波导叠加型光栅的解波分复用特性进行研究,发现了入射角度通过改变耦合系数会对光栅的反射率和带宽产生影响:当入射角度较大时,单个光栅的反射率虽稍有增大,但带宽变宽;而在入射角度较小时尽管其反射率稍有下降,但带宽却显著变窄.因此在光栅设计时必须综合考虑反射率和带宽的要求以获得更好的解波分复用性能·

Utilizing the glass photosensitivity. The supergratings can be fabricated with the function of wavelength-division demultiplexing in the planar waveguide. Through the study of the demultiplexing characteristics of planar waveguide supergratings based on the theory of mode coupling,the authors found that by influencing the coupling index, the angle of incident light can affect the reflectivity and bandwidth of gratings. When the incident light angle is large, although the reflectivity of the grating becomes large slightly, the bandwidth becomes wide. When the incident angle is small, although the reflectivity decreases slightly, the bandwidth becomes narrow obviously. In order to achieve the better demultiplexing performance, the requirements of reflectivity and bandwidth must be considered synthetically when designing the supergrating.