A high-Q biochemical sensor using a total internal reflection mirror-based triangular resonator with an asymmetric Mach–Zehnder interferometer

Abstract

We propose and analyze a high effective Q-factor triangular ring resonator (TRR) coupled with an asymmetric Mach–Zehnder interferometer (AMZI), in which the long evanescent fields on a total internal reflection (TIR) mirror in the TRR and the field cancelation by the phase difference of each path in the AMZI are utilized. The TRR is employed in order to more effectively measure the quantities that occur during biological events because the evanescent field of the TIR mirror with its sharp incident angle is influenced by the Goos–Hänchen shift. In this paper, we report upon the AMZI-coupled TRR sensor structure with the high effective Q-factor of about 105 obtained through the optimization of the AMZI path-length. The sensitivity of the resonance shift when changing the refractive index of 1×10−4 at the incidence angle of 22.92° has been identified to be as high as 0.48×104nm/RIU. In addition, the power sensitivity of the AMZI-coupled TRR with a 17dB attenuation is 5.7×105dB/RIU.