Strain sensing with fiber-based optical-frequency-comb cavity

Abstract

In this paper, we proposed a novel strain sensor employing optical-frequency-comb cavity. The strain sensing was realized by strain/radio-frequency conversion in a fiber-based optical frequency comb cavity. The fiber-based optical frequency comb cavity generated a repetitive pulse train of which the repetition rate was determined by the cavity length. The application of mechanical strain onto the cavity produced the extension or compression of the cavity length, resulting the change of repetition rate of the pulse train. The resultant strain can be detected by observing the change of repetition rate of the pulse train with a frequency analyzer. For a proof-of-principle demonstration, we constructed an Er-doped fiber-based optical frequency comb system for the strain sensing. We demonstrated static and dynamic strain sensing with the developed system, and realized the strain sensitivity of 84.5 nε in the static strain sensing and that of 15 nε in the dynamic strain sensing with 2 m sensing fiber length. Our results demonstrated the efficacy of the strain sensor employing the optical-frequency-comb cavity.