High common mode rejection ratio InP 90° optical hybrid in ultra-broadband at 60 nm with deep-rigded waveguide based on × 4 MMI coupler

Lu Zi-Qing^{1, 2}, Han Qin^{1, 2, 3, †}, Ye Han^{1, 2}, Wang Shuai^{1, 2}, Xiao Feng^{1, 2}, Xiao Fan^{1, 2}

Field distribution of 90° hybrid for single input at (a) port 1 and (b) port 3, and (c) for two input ports with different phase differences.