Suppressing the crosstalk between racetrack resonators by grating assisted couplers for WDM sensing

We proposed a uniform racetrack resonators based sensor for bio-chemical WDM sensing. The sensing channels are assigned by grating assisted contra-directional couplers. Each resonator only occupies one sensing channel. The crosstalk between sensing channels can be suppressed by aligning the center coupling wavelength of one resonator with the weak coupling wavelength of the others. Based on the simulation results obtained from transfer matrix method, the sensing channel gap can be reduced down to 2 FSRs (~1.5 nm) of the resonator. The total crosstalk can be as low as 2.5?×?10?2 dB in a sensor with 23 channels covering the whole C band. This sensor with high throughput will be very important for analyzing a wide range of analytes, such as organic compounds or biological materials.