Highly Efficient Grating Coupler for SOI Integrated Photonics label free Bio-sensing Application

Integrated photonics based on silicon on insulator (SOl) using CMOS manufacturing process is a promising candidate for level free bio-sensing application. In this article we discuss on the principle and importance of level free bio-sensing. Then we present the design process and the finite difference time domain (FDTD) simulation result of building blocks for a typical optical ring resonator based integrated photonic bio-sensor operating at 1550nm. The resonance frequency of the design is 1550nm which experiences very low loss. Our designed ring has a radius of 10um, coupling gap between ring and waveguide of 150nm and waveguide width of 500nm. Input grating coupler has a period of 600nm with duty cycle of 0.67. The grating height is 175nm with 38 total periods. The output coupler has filling factor of 0.35 and period of 550nm with grating height of 250nm. There are total 25 periodic structure at output coupler. The SOI wafer has a silicon thickness of 340nm and buried oxide layer thickness of 1000nm. The overall efficiency of the grating coupler from input to output of the sensor is 42 percent. Index Term— Label free, bio-sensor, ring resonator, coupling, optical sensor, Grating Coupler, Integrated Photonics, bio fictionalization, FDTD