Tunable Fiber Laser With Ultra-Narrow Linewidth Using A Tunable Phase-Shifted Chirped Fiber Grating

We experimentally demonstrate a tunable C-band erbium-doped fiber ring laser with ultra-narrow linewidth using a tunable phase-shifted linearly chirped fiber Bragg grating (PS-LCFBG) as an intracavity ultra-narrowband filter. The center wavelength of the PS-LCFBG with an ultra-narrow bandwidth of <10 pm is thermally tuned by scanning a current-controlled resistance wire along its length. The laser has an ultra-narrow linewidth of <1.52 kHz, a tuning range of ~15.5 nm, a good side-mode suppression ratio of >30 dB, an output power of ~10 dBm, a small power variation of <0.2 dB, and a small wavelength variation of <0.01 nm. The laser structure is simple and cost-effective.