偏振分束旋转器(PSR)是解决绝缘衬底上硅(SOI)平台光波导器件偏振敏感问题的关键性器件。SOI波导材料的折射率差大,使得横电模(TE)和横磁模(TM)的有效折射率差值很大,故器件对偏振态敏感。偏振分束旋转器可有效解决这一问题,光波经过PSR后可以两束同偏振态的模式光输出。根据模式转换机制的不同,PSR分为基于模式耦合和基于模式演化两类。分别介绍对应器件的研究进展。基于模式耦合原理的PSR,模式转换过程一步实现,设计简单,具有小尺寸、工艺易实现的特点;基于模式演化原理的PSR,模式转换分两步完成,结构复杂,具有大带宽、大容差的特点。此外,还介绍了中红外波段的PSR,并对硅光偏振分束旋转器的未来发展趋势做出预测。

The polarization splitter-rotator (PSR) is a key device for solving the problem of polarization sensitivity of optical waveguide devices in silicon-on-insulator (SOI) platform. The refractive index difference of SOI waveguide materials is large, making the difference in effective refractive index between the transverse electric mode (TE) and the transverse magnetic mode (TM) large, resulting in the device being sensitive to polarization state. The PSR can effectively solve this problem. Light waves pass through the PSR and the output is received as two modes with the same polarization state. This paper introduces the research progress of devices based on two different mode conversion mechanisms: mode coupling and mode evolution. For PSRs based on the mode coupling principle, mode conversion is realized in one step, and they have a simple design, are compact, and are easy to fabricate. Whereas, for mode evolution PSRs, mode conversion is completed in two steps, and they have a complex structure, large bandwidth, and large fabrication tolerances. Additionally, PSRs operating in the mid-infrared are introduced, and the future trends of silicon polarization splitter-rotators are predicted.