Ultracompact Vernier-effect-improved sensor by a single microfiber-knot resonator

Fiber-optic sensors are an indispensable element of modern sensing technologies by virtue of their low cost, excellent electromagnetic immunity, and remote sensing capability. Optical Vernier effect is widely used to enhance sensitivity of fiber-optic sensors but requires bulky and complex cascaded interferometers. Here we propose and experimentally demonstrate an ultracompact (-2 mm by -2 mm) Vernier-effect-improved sensor by only using a single microfiber-knot resonator. With the Vernier effect achieved by controlling the optical beating with the spectral ripple of a super light emitting diode (SLED), we show -20x sensitivity enhancement for quantitative temperature monitoring. Our sensor creates a new practical method to realize Vernier effect in fiber-optic sensors and beyond.

Automated summary

Fiber-optic sensors are widely used in modern sensing technologies due to their low cost, strong electromagnetic interference immunity, and remote sensing capability. We propose and experimentally demonstrate an ultracompact Vernier-effect-improved sensor using only a single microfiber-knot resonator. By controlling the optical beating with the spectral ripple of a super light emitting diode (SLED), we achieve 20x sensitivity enhancement for quantitative temperature monitoring. Our sensor provides a practical method to realize the Vernier effect in fiber-optic sensors and opens up new possibilities for their development.