Subwavelength TE/TM grating coupler based on silicon-on-insulator

In this letter, we report a novel uniform grating coupler, which can couple the light of different polarization from fiber into a single waveguide at same wavelength range. When incident wavelength is 1550 nm, for TE mode, the coupling efficiency can achieve more than 50% with ∼30 nm 1 dB bandwidth. For TM mode, the coupling efficiency can also obtain more than 50% and 35 nm 1 dB bandwidth. Their corresponding wavelength difference between two polarizations' coupling peaks is demonstrated to be less than 5 nm reported in this letter. Many limits of application about influence of polarization-depend can be solved by this design.