Xu ZhengYing, Tu Bin, Liu Hao
Opt Express. 2024 Apr 8;32(8):13156-13165. doi: 10.1364/OE.520833.
A novel ultra-broadband TM-pass polarizer with high polarization extinction ratio (PER) and low reflection has been proposed and demonstrated by utilizing multimode Bragg grating waveguide (MBGW) and two tapered waveguides. By optimizing the period of the MBGW, the injected TE mode is coupled into the backward TE mode and effectively leaked into the cladding. Meanwhile, the injected TM mode propagates through the polarizer without any negative impact. The operation bandwidth can be significantly expanded by cascading multiple MBGW structures, each of which operates at a different central Bragg wavelength. The simulation results indicate that the designed polarizer can achieve an insertion loss (IL) below 0.24 dB and a PER above 39 dB simultaneously across a bandwidth of 300 nm (1400 nm∼1700nm), while the reflected signal is below -9.1 dB. The experiment results demonstrate that the fabricated polarizer can realize an IL below 0.56 dB and a PER above 33 dB in a 160 nm bandwidth ranging from 1470 nm to 1630 nm. Due to limitations in the equipment used, measurements for other wavelength ranges are not conducted. With these merits, the proposed device would find significant applications in optical communication systems.
通过利用多模布拉格光栅波导（MBGW）和两个锥形波导，提出并演示了一种具有高偏振消光比（PER）和低反射率的新型超宽带TM模偏振器。通过优化MBGW的周期，注入的TE模被耦合到反向TE模中并有效地泄漏到包层中。同时，注入的TM模在偏振器中传播而没有任何负面影响。通过级联多个MBGW结构可以显著扩展工作带宽，每个结构在不同的中心布拉格波长下工作。仿真结果表明，所设计的偏振器在300nm（1400nm∼1700nm）带宽内可同时实现低于0.24dB的插入损耗（IL）和高于39dB的PER，而反射信号低于-9.1dB。实验结果表明，所制备的偏振器在1470nm至1630nm的160nm带宽内可实现低于0.56dB的IL和高于33dB的PER。由于所用设备的限制，未对其他波长范围进行测量。具有这些优点，所提出的器件将在光通信系统中找到重要应用。
