Role of Coupling Angle on the Performance of a Ring Resonator–Waveguide Sensor

In the present work, the effect of coupling angle on the coupling of light from a ring resonator to a bent-waveguide has been studied. It has been shown that by bending the waveguide along the ring, the percentage of first trip light coupling from the resonator into the waveguide can be increased up to a particular value of coupling angle named as θm. It has been seen that beyond θm, the light coupling percentage starts decaying and ends up with a zero coupled light in the bus waveguide. For getting more light coupled to the waveguide, the value of θm should increase and it has been done by reducing the waveguide core width. Suitable choice of the coupling angle helps achieve a very high FSR and Q of the ring resonator.