Mode conversion and birefringence adjustment by focused-ion-beam etching for slanted rib waveguide walls.
We describe how focused-ion-beam (FIB) etching of slanted rib waveguide walls can be used to modify the differential group delay in a waveguide and introduce TE to TM mode conversion in a silicon-on-insulator rib waveguide. We achieved mode conversion by modifying the geometric cross section of a single-mode rib by FIB trimming. Waveguides with different lengths of 45 degrees slant angle rib waveguide walls were fabricated and characterized. We measured the differential group delays and the mode conversion achieved for waveguides with different lengths of a FIB-trimmed slanted rib wall.
Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. pschan@ee.cuhk.edu.hk
Po Shan
PS
Chan
H K
HK
Tsang
C
C
Shu