Hou Jin, Wang Linzhi, Yang Chunyong, Wang Bing, Chen Shaoping
Appl Opt. 2015 Dec 1;54(34):10277-82. doi: 10.1364/AO.54.010277.
A compact high extinction ratio polarization beam splitter based on an asymmetric directional coupler was proposed and theoretically investigated. The asymmetric directional coupler consists of a silicon wire waveguide and a 1D periodic silicon rods waveguide, which results in an ultracompact polarization splitting length. By using the plane wave expansion method, a minimum coupling length of 3.43 μm was obtained, and the length was then confirmed by finite-difference time-domain simulation. Moreover, for 1550 nm wavelength, high extinction ratios of about 28 and 18 dB were also observed for TE and TM polarizations, respectively. The ultrahigh extinction ratio for TE polarization is mainly arising from the appearance of TM bandgap in the periodic rods waveguide. In addition, for both polarizations, the extinction ratios are all above 10 dB covering a 180 nm bandwidth, and it was also demonstrated that the device has a high transmission for TM polarization.
提出并从理论上研究了一种基于非对称定向耦合器的紧凑型高消光比偏振分束器。该非对称定向耦合器由一根硅线波导和一个一维周期性硅棒波导组成，这使得偏振分裂长度超紧凑。通过平面波展开法，得到了3.43μm的最小耦合长度，然后通过时域有限差分模拟对该长度进行了验证。此外，对于1550nm波长，TE和TM偏振的消光比分别约为28dB和18dB。TE偏振的超高消光比主要源于周期性棒波导中TM带隙的出现。此外，对于两种偏振，在180nm带宽内消光比均高于10dB，并且还证明了该器件对TM偏振具有高透射率。
