Erbium Ring Fiber Laser Cavity Based on Tip Modal Interferometer and Its Tunable Multi-Wavelength Response for Refractive Index and Temperature

Abstract

A tunable multi-wavelength fiber laser is proposed and demonstrated based on two main elements: an erbium-doped fiber ring cavity and compact intermodal fiber structure. The modal fiber interferometer is fabricated using the cost-effective arc splice technique between conventional single-mode fiber and microfiber. This optical fiber structure acts as a wavelength filter, operated in reflection mode. When the refractive index and temperature variations are applied over the fiber filter, the ring laser cavity provides several quad-wavelength laser spectra. The multi-wavelength spectra are tuned into the C-band with a resolution of 0.05 nm. In addition, the spectra are symmetric with minimal power difference between the lasing modes involved, and the average of the side mode suppression ratio is close to 37 dB. This laser offers low-cost implementation, low wavelength drift, and high power stability, as well as an effect of easy controllability regarding tuned multi-wavelength.

Fiber Laser Sensor Configurations for Refractive Index, Temperature and Strain: A Review

“…In the last decades, several research groups have employed different optical fiber structures as sensing heads in fiber laser sensors: tapers [27], multimode interference filters [28], and all fiber interferometers [29][30][31][32]; these elements improve the possibility of tuning a lasing mode. As a consequence, multiple parameters have been detected using fiber laser sensors: refractive index [33,34], curvature [35,36], strain [37][38][39], temperature [40][41][42][43][44], magnetic field [45,46], liquid level [27,47], torsion [48], rotation [49], gas concentration [29,50], gas pressure [51,52], relative humidity [32,53], and ultrasound [54].…”