Ultra-short DBR fiber laser with high-temperature resistance using tilted fiber Bragg grating output coupler

We demonstrate a high-temperature resistant distributed Bragg reflector (DBR) fiber laser that is highly compact with an entire cavity length of 12 mm. A partial-reflection tilted fiber Bragg grating (PR-TFBG) is used as the laser output coupler whose reflectivity can be adjusted by changing the TFBG tilt angle. The laser cavity consists of two strong gratings including the PR-TFBG and a high-reflection fiber Bragg grating (HR-FBG), which is directly fabricated in an Er-doped fiber using a femtosecond laser and a phase mask. The thermal stability of the PR-TFBG and HR-FBG is experimentally investigated. After an annealing process, their remained gratings are stable at high temperatures and strong enough for laser oscillation. The laser is also annealed before its stability is tested. The results show that the laser can stably operate in single longitudinal mode with a signal-to-noise ratio better than 65 dB over the temperature range from room temperature to 550°C.