新型一维复合光栅的光学反射特性分析

Analysis of Optical Reflection Characteristics of a New One-Dimensional Compound Grating

摘要: 利用严格耦合波分析法(RCWA)分别计算了TE入射、TM入射和锥形入射下不同占空比的复合光栅的反射率，分别从波长、光栅槽深度d和光栅周期等结构参数进行数值模拟。计算结果表明：周期为2 μm，光栅厚度为1 μm，占空比为f₁、f₂、f₃的新型一维复合光栅结构反射达到了预期效果，符合初期对复合光栅的设想。对于光通信器件，波长为1.55 μm的复合光栅具有更好的信息保护和防丢失能力；光栅槽深度d为0.5 μm时，TE入射情况下的特定复合光栅的反射率收敛于78%；同一反射率下，复合光栅的光栅周期要比矩形光栅小，节约了实际成本，并且在TM入射情况下，复合光栅的反射率范围更广。对一维复合光栅反射特性的研究，优化了光通信器件对于信息的保护，使得反射率可以收敛于特定值，也为实际工艺提供了光栅设计和制作理论。

Abstract: The reflection efficiency of compound grating with different ratio (duty cycle) under TE incident, TM incident and conical incident was calculated by using strict coupled wave analysis (RCWA), and the structural parameters such as wavelength, normalized groove depth and grating period were simulated. The results show that the reflection of the new one-dimensional composite grating structure with period of 2 μm, grating thickness of 1 μm, duty cycle of f₁, f₂, f₃, has achieved the desired results, in line with the initial idea of composite grating. For optical communication devices, the composite grating with wavelength of 1.55 μm has better information protection and anti-loss ability. When the normalized groove depth is 0.5 μm, the reflection efficiency of the specific composite grating under TE incidence converges to 78%; under the same reflection efficiency, the grating period of composite grating is smaller than that of rectangular grating , which saves the actual cost, and the reflection efficiency range of composite grating is wider under TM incidence. The research on the reflection characteristics of one-dimensional composite grating optimizes the information protection of optical communication devices, so that the reflection efficiency can converge to a specific value. It also provides the grating design and fabrication theory for the actual process.