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
(a) Schematic diagram and (b), (c) SEM imagings of fabricated 90° hybrid.