Theoretical investigation of two beams optical ring resonators for new generation photonic sensors

The ring resonator is an integrated optical structure where the light propagates in the form of whispering gallery modes (WGMs) resulting from the total internal reflection of the light along the curved surface. The WGM circulating along the closed loop waveguide realizes an optical feedback mechanism very sensitive to any external perturbation. In this work we report on the interaction between the modes of two beams having the same frequency counterpropagating within the ring. In this case the travelling wave (TW) beams, counterpropagating in the ring, generate a resonant standing wave (SW) that, in turn, couples with a pair of straight (bus) waveguides. This physical mechanism can be used for enhancing the performance of new ring resonator based photonic sensors.