High-sensitivity refractive index sensor based on Ge–Sb–Se chalcogenide microring resonator

Abstract In this article, we report a liquid sensing device based on a Ge–Sb–Se microring resonator (MRR) operating at a wavelength of 1550 nm. The transmission loss of the waveguide is 4.3 dB/cm, and the intrinsic Q factor of the MRR is 7.74 × 104, with an extinction ratio of approximately 40 dB. By detecting the different concentrations of NaCl solutions, we observe that the sensitivity of our proposed device is approximately 123 nm/RIU, and the intrinsic limit of detection is approximately 3.24 × 10−4 RIU. Compared with the other materials, such as silicon, Si3N4, or polymer, the moderate refractive index (RI) of Ge28Sb12Se60 glass allows it to obtain a high sensitivity and a high Q factor, while maintaining a strong confinement on the light field to avoid suffering from bending loss under a small bending radius, with a compact structure.