Integrated optical microring for high-resolution refractive index and pressure sensing applications

摘要

Whispering-gallery mode (WGM) resonators such as microspheres, microcylinders, and microrings have been proposed for telecommunication and sensing applications for decades. However, several challenges, such as the robustness of the optical coupling and sample delivery means, were often found in the path of developing them for the real world sensing applications. In this paper, a robust microring platform based on integrated lightwave circuit technology and a tunable laser interrogation system has been demonstrated as high-resolution refractive index and pressure measurement system. By using a "two-point" interrogation scheme and a microring with Q factor of about 24,000, a refractive index sensitivity of about 145 nm/RIU (TM mode) and 205 nm/RIU (TE mode) for two different polarizations and a limit of detection on the order of 10-7 RIU have been demonstrated. For the high-pressure measurement applications, a pressure resolution of 0.05 psia has been achieved.