Investigation of the fibre to chip coupler designed on SOI platform with subwavelength grating

In this paper, investigation of the fibre to chip coupler designed on SOI platform with subwavelength grating is reported. This fibre to chip coupler was designed on SOI platform with subwavelength grating, which is compatible with DUV lithography and single step etching fabrication process, for effective refractive index tuning and matching to silicon wire waveguide. The simulation and investigation of the fibre to chip coupler was performed by 3D FDTD tool and BPM tool. The effective refractive index was tuned over diffraction grating by adjusting the duty cycle of the silicon in subwavelength grating of the low refractive index part of the diffraction grating. We investigate by simulation how variation effective refractive index tuning along diffraction grating affect the power profile of the diffracted field from coupler and peak coupling wavelength.