A high peak-power and narrow-linewidth all-fiber Raman pulsed laser operating around 1.65 µm is introduced. A 1541 nm laser seed is modulated into pulse trains, which will be used as the Raman pump laser, by driving a reflective semiconductor optical amplifier (RSOA) with a continuous periodic square-wave voltage. A homemade high peak-power 1541 nm pulsed laser is employed to modulate and amplify a 1653.7 nm distributed feedback laser (DFB) seed synchronously in a segment of the 52-meter-long highly germania-doped fiber (HGDF). The repetition-rate and the pulse-width of the 1653.7 nm pulsed laser are 100 kHz and 31 ns, respectively. The peak power is estimated to be as high as about 30.85 W, and a 3-dB linewidth as narrow as less than 0.08 nm is achieved when the average power of 1541 nm pump is 3.1 W. The wavelength of Raman pulsed laser can be tuned from 1652.0 nm to 1654.0 nm continuously with an optical signal-to-noise ratio (OSNR) of more than 35 dB.

We present a linearly polarized single-longitudinal-mode (SLM) ytterbium-doped fiber laser with a polarization extinction ratio (PER) of over 35 dB and a narrow linewidth of less than 4.5 kHz. The very high PER is obtained by utilizing the polarization evolution effect at the optical fiber and the high-performance polarizing beam splitter. The SLM is achieved by using a segment of polarization-maintaining ytterbium-doped fiber as a narrowband filter. In addition, a high optical signal-to-noise ratio of 50 dB and a good slope efficiency of 60.5% are achieved. Using an ytterbium-doped fiber amplifier, a linearly polarized SLM laser system with a high power of over 2.5 W is demonstrated at 1064 nm.