Onawa Yosuke, Okayama Hideaki, Shimura Daisuke, Yaegashi Hiroki, Sasaki Hironori, Kashima Masayuki
Opt Express. 2020 Dec 21;28(26):39227-39240. doi: 10.1364/OE.412069.
Multimode based polarization independent (PI) wavelength division multiplexing (WDM) devices are proposed and experimentally demonstrated. The key concept is to utilize two different order modes for the orthogonal polarizations, ith-order mode for TE and jth-order mode for TM (i ≠ j) polarization respectively to extend the flexibility for designing devices. PI coupler composed of a multimode directional coupler and mode converters is introduced as a basic device. Then, we apply PI coupler to Mach Zehnder interferometer (MZI) and Bragg grating bandpass filters. PI MZI is achieved by optimizing the combination of two phase shifters in the interferometer arms. PI bandpass uses 3dB-PI coupler and polarization rotate Bragg gratings that induce mode coupling between the polarizations. Each device showed good matching in the spectrum between TE and TM polarizations in term of operation wavelength. The proposed concept can be a promising approach to realize PI WDM functions without introducing polarization diversity scheme in which a polarization beam splitter, two devices designed for each polarization and a polarization beam combiner are required.
提出并通过实验证明了基于多模的偏振无关（PI）波分复用（WDM）器件。关键概念是利用两种不同阶模用于正交偏振，分别用第i阶模用于TE偏振，第j阶模用于TM偏振（i≠j），以扩展器件设计的灵活性。引入由多模定向耦合器和模式转换器组成的PI耦合器作为基本器件。然后，我们将PI耦合器应用于马赫曾德尔干涉仪（MZI）和布拉格光栅带通滤波器。通过优化干涉仪臂中两个移相器的组合来实现PI MZI。PI带通使用3dB - PI耦合器和偏振旋转布拉格光栅，其在偏振之间诱导模式耦合。每个器件在工作波长方面在TE和TM偏振的光谱中都表现出良好的匹配。所提出的概念可能是一种有前途的方法，可在不引入偏振分集方案的情况下实现PI WDM功能，在偏振分集方案中需要一个偏振分束器、为每个偏振设计的两个器件以及一个偏振合束器。
