平场输入/输出蚀刻衍射光栅的设计

光通信中波分复用技术是解决通信网络瓶颈的有效手段，近年来得到很大发展。以平面波导波分复用器件为核心的密集波分复用技术已经得到成功商用。蚀刻衍射光栅是平面波导密集波分复用器件中很有发展潜力的一种。原有蚀刻衍射光栅采用罗兰圆设计，输入输出在圆弧曲线上由条形波导引出；而平场输入／输出的蚀刻衍射光栅在很多应用中可以省去制作输入输出波导，大大简化制作工艺，同时能够保持良好的线性色散和聚集效果。给出了平场输入和输出蚀刻衍射光栅的设计方法，并利用标量衍射理论对设计的结果进行模拟，验证了平场输出蚀刻衍射光栅具有很好的分波效果。

Design of an Etched Diffraction Grating with Flat-Field Input/Output

Wavelength division multiplexing (WDM) is in a great development recent years to meet the fast-grown demand for the communication capacity, and dense wavelength division multiplexing (DWDM) has been put into a successful commercial use. As a key device in a DWDM system, etching diffraction grating (EDG) is a planar waveguide DWDM device with a great potential. Although an EDG is harder to fabricate than an AWG (arrayed waveguide grating), it has a better spectral fineness and can easily implement more output channels. A design method for an EDG of flat input/output is presented. The scalar diffraction theory is used to verify the design, the numerical results show that the designed EDG has a good performance. A conventional EDG design is based on the Rowland circle on which the end points of the input and output waveguides are located. This configuration has a good focal property but needs the fabricating of the output channels to couple the light with output fibers. An EDG of flat-field input/outputs can also maintain a good linear dispersion and a perfect focused field as a conventional EDG.