Based on core- and in-band-pumped polarization-maintaining T m 3 + -doped single-cladding fiber (PM-TSF, the core diameter is 9 µm) by a 1610 nm fiber laser and a distributed Bragg reflector seed laser, a linearly polarized single-frequency fiber laser (LP-SFFL) at 1950 nm with an output power of 55.3 W and a laser linewidth of 6.95 kHz is demonstrated. The output beam qualities of M x 2 and M y 2 are measured to be 1.01 and 1.03, respectively. The slope efficiency with respect to the launched pump power is 71.0%, in comparison with a theoretical quantum efficiency of 82.6%. A polarization-extinction ratio of 19 dB and an optical signal-to-noise ratio of 58 dB are obtained from the 1950 nm LP-SFFL. To the best of our knowledge, to date, this is the highest power of 2.0 µm SFFL output directly from a strict single-mode active fiber. Our experiment offers a promising solution to the current limitations of the high-performance fiber lasers at 2.0 µm, which is particularly essential for coherent detection.

No abstract

No abstract

An all-fiber high-power and broad-frequency-band near-shot-noise-limited kHz-linewidth (Δν ~1.7 kHz) single-frequency master-oscillator power amplifier (MOPA) laser at 1.5 μm is demonstrated. To significantly suppress the intensity noise of seed laser and mitigate the detrimental effects of amplified spontaneous emission and stimulated Brillouin scattering in fiber amplifiers, more than 23 W of a stable low noise single-frequency laser output is achieved with a relative intensity noise of < -150 dB/Hz @0.5 mW (near to the shot-noise limit: -152.9 dB/Hz) in the frequency band from 0.1 to 50 MHz. It is believed that the achieved laser performance of ultra-low intensity noise and high-power output make the laser source become a promising candidate in further applications, such as cold atom optical lattice, quantum key distribution, and gravitational wave detection.

Based on a 1.8-cm-long heavily Tm-doped germanate fiber and being in-band-pumped by a 1610 nm single-mode laser, a high-efficiency and high-power single-frequency distribute Bragg reflector (DBR) fiber laser emitting at 1950 nm is demonstrated. The DBR fiber laser has a maximum output power of ~617 mW and a slope efficiency for the absorbed pump power reaches to more than 42.2%. A stable single-longitudinal-mode laser output with a signal-to-noise ratio of greater than 63 dB is realized. The measured relative intensity-noise of the fiber laser reaches to around -150 dB/Hz at frequencies of over 8.4 MHz. It is beneficial to exploit the sub-watt and high-efficiency single-frequency laser from fiber oscillators directly, especially in the application of multiple paths coherent beam combination and optical medical technology.