Ultra-compact silicon mode (de)multiplexer based on directional couplers with subwavelength sidewall corrugations
Xiaofei Wang, Hui Yu, Qiang Zhang, Zhilei Fu, Penghui Xia, Qikai Huang, Nannan Ning, Zhujun Wei, Yuehai Wang, Xiaoqing Jiang, Jianyi Yang
Abstract
Asymmetrical directional couplers aided with subwavelength sidewall corrugations are used to realize ultra-compact silicon mode (de)multiplexers at C-band. Three mode (de)multiplexers with ultra-short coupling lengths of 5.6/6.5/7.7 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>μ</mml:mi> </mml:mrow> </mml:math> m are designed to enable low-loss mode conversions between TE 0 and TE 1/2/3 modes. They are then cascaded to build a four-channel mode-division-multiplexing (MDM) link. The four mode channels present minimal on-chip insertion losses of 0.2/0.7/0.7/0.9 dB at their peak wavelengths. Measured cross talk levels of the four mode channels are better than −18.0/−19.1/−16.0/−18.2 dB within the wavelength range from 1530 nm to 1580 nm.