SiN_(x)填充的定向耦合器型偏振无关解复用器

Directional Coupler-Based Polarization-Independent Demultiplexer Filled with SiN_(x)

设计了一种基于SiN_(x)填充的定向耦合器(DC)型偏振无关解复用器,用于分离1310 nm和1550 nm两个波长的光信号。采用等离子体增强化学气相沉积(PECVD)方法调节DC波导间隙内填充的SiN_(x)材料的折射率,使同一波长下横电(TE)偏振模和横磁(TM)偏振模的耦合长度相等,实现器件的偏振无关功能。通过优化波导间隙,调整两个波长光信号所对应的耦合长度比,选择合适的值可使其分别从两个端口输出,实现波长分离功能。运用三维有限时域差分方法进行建模仿真,对器件进行参数优化和性能分析。结果表明:所提出的解复用器的耦合区长度仅为22.8μm,插入损耗和串扰(CT)分别低至0.05 dB和-21.58 dB,CT小于-10 dB的带宽可达79 nm,且总体容差性良好。所设计的器件在未来的集成光路系统中具有潜在的应用价值。

A directional coupler(DC)-based polarization-independent demultiplexer filled with SiN_(x)is designed to separate the 1310-nm and 1550-nm optical signals.The plasma-enhanced chemical vapor deposition(PECVD)method is used to adjust the refractive index of the SiN_(x)material filled in the gap between the DC waveguides.As a result,the coupling length of the transverse-electric(TE)polarization mode equals that of the transverse-magnetic(TM)polarization mode at the same wavelength,and the polarization-independent function of the device is thereby fulfilled.The ratio of the coupling lengths corresponding to the two optical signals with different wavelengths is adjusted by optimizing the gap between the waveguides.When a proper value of the coupling length ratio is chosen,the two optical signals can be output from two ports,respectively,to achieve the wavelength separation function.Modeling and simulation are conducted by the threedimensional finite-difference time-domain method to optimize the parameters of the device and analyze its performance.The results show that the proposed demultiplexer achieves a coupling region as short as 22.8μm and an insertion loss and a crosstalk(CT)as low as 0.05 dB and-21.58 dB,respectively.Besides,the bandwidth corresponding to a CT smaller than-10 dB reaches 79 nm,and the device offers favorable tolerance on the whole.The device designed has application potential in future integrated optical circuit systems.