Narrow-linewidth high-efficiency single-frequency ytterbium-doped fiber laser with highly linear polarization at 1064 nm.

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.

High peak-power and narrow-linewidth all-fiber Raman nanosecond laser in 1.65 µm waveband.

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.

400 mW narrow linewidth single-frequency fiber ring cavity laser in 2 um waveband.

We present a single-frequency thulium-doped fiber laser (TDFL) with a narrow linewidth of 20 kHz. Stable single-longitudinal-mode (SLM) lasing operation at 1957 nm is achieved using a segment of un-pumped polarization-maintaining thulium-doped fiber (PM-TDF) as an ultra-narrow bandwidth filter. A high optical signal-to-noise ratio (OSNR) of over 60 dB is obtained and a high power of over 400 mW is achieved with a high slope-efficiency (~45.8%) thulium-doped fiber amplifier (TDFA).

Generation of high-power 780 nm femtosecond pulses by an all-polarization-maintaining Er-doped fiber amplification system.

A 187 fs pulse laser with 2.3 W of output power at 1560 nm is built for second-harmonic generation (SHG), which is the highest average power output reported from an all-polarization-maintaining single-mode Er-doped chirped pulse amplification system. By subsequently using an MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal as frequency doubler, a 183 fs pulse laser with 1.1 W output power at 778 nm is generated. Benefitting from a polarization-stable fundamental laser input and the temperature control of the PPLN crystal, the power fluctuation of the frequency doubled laser is less than 0.5% during 24 h. To the best of our knowledge, the 1.1 W output at 780 nm band is also the highest average power generated from a frequency doubled femtosecond Er-doped fiber laser.

Performance evaluation of continuous-wave mid-infrared wavelength conversion in silicon waveguides.

Continuous-wave (CW) mid-infrared (MIR) wavelength conversion is experimentally demonstrated using degenerate four-wave mixing (FWM) between two thulium-doped fiber (TDF) lasers in a silicon waveguide. One TDF laser is homemade with a high power and tunable wavelength, while the other one is a commercial product. The conversion efficiency is measured with respect to the pump power and the signal wavelength detuning. In the 2 µm MIR band, the measured 3 dB conversion bandwidth is 52 nm. It verifies the feasibility of FWM-based wavelength conversion based on silicon waveguides in future MIR optical communication systems.

Widely wavelength-tunable 2 µm Brillouin fiber laser incorporating a highly germania-doped fiber.

We present, for the first time to our knowledge, a wavelength-tunable 2 µm Brillouin fiber laser based on a homemade thulium-doped fiber laser pump and a segment of highly germania-doped fiber (HGDF). The laser wavelength can be continuously tuned over 110 nm from 1920 to 2030 nm with single frequency operation, and the linewidth is estimated to be less than 0.9 kHz at 1950 nm. Benefiting from the high nonlinearity and low loss of the HGDF, a low lasing threshold of 47 mW is also achieved.