Tunable Single-wavelength Fiber Laser Based on a Microbubble Cavity

A tunable fiber laser with feedback based on a high-quality factor
$\boldsymbol{(Q\sim 10^{7})}$
microbubble cavity is suggested and demonstrated. The single-wavelength fiber laser output with a linewidth of
$\boldsymbol{\sim 11.68\ \text{kHz}}$
and a threshold power of approximately 35mW is achieved by incorporating a microbubble cavity-tapered fiber coupling system into an all-fiber ring laser. The tuning method of fiber lasers is achieved by the pressure variations within the microbubble cavity in the feedback loop, which has the advantages of fast tuning and continuous tuning. And a wavelength sensitivity of 0.1291 pm/kPa is obtained. This tunable fiber laser has several applications in optical fiber communications, fiber sensors, and other fields.