Jiaqun Zhao

Diode-pumped continuous wave and passively Q-switched Tm,Ho:LLF laser at 2 µm

A compact diode-pumped continuous wave and passively Q-switched Tm,Ho:LuLiF(4) laser is demonstrated. The maximal output power of 381 mW at 2069 nm in continuous wave regime is obtained at an absorbed pump power of 1.5 W. By using a Cr(2+):ZnS saturable absorber, the maximum Q-switched average output power of 74 mW is obtained at 2055 nm. The pulse width and pulse energy are almost independent of the absorbed pump power, with the maximal values of 1.2 μs and of 13 μJ respectively. The pulse repetition frequency can be tuned almost linearly from 1 to 5.8 kHz by changing the absorbed pump power. Furthermore, a comparative analysis of laser performances with different output couplers is first carried out.

Diode-pumped actively Q-switched Tm, Ho:GdVO 4 /BaWO 4 intracavity Raman laser at 2533 nm

A compact diode-end-pumped actively Q-switched intracavity Raman laser with Tm,Ho:GdVO(4) laser gain medium and BaWO(4) Raman gain crystal is demonstrated for the first time. The Raman threshold is as low as 2.0 W of diode power at 802 nm. The highest average output power of 186 mW at the first Stokes wavelength of 2533 nm is obtained at a pulse repetition rate of 1 kHz, and a pump power of 2.8 W, corresponding to a diode-to-Stokes optical conversion efficiency of 6.6%. The pulsewidth and pulse energy are 7.8 ns and 0.19 mJ, respectively.

Diode-end-pumped continuously tunable single frequency Tm, Ho:LLF laser at 2.06 μm

We report on a laser diode-end-pumped continuously tunable single frequency Tm, Ho:LLF laser near room temperature. For transmission of 5%, the maximum single frequency output power of 221 mW at 2064.4 nm was obtained by using two uncoated etalons. The single frequency Tm, Ho:LLF laser operated on the fundamental transverse mode with an M2 factor of 1.13, and the output frequency could be tuned continuously near 1.5 GHz by angle tuning only of the 1 mm thick etalon. Furthermore, the influence of output coupler transmission on the laser performance was also investigated. The single frequency laser can be used as a seed laser for coherent Doppler lidar and differential absorption lidar systems.

Diode-pumped actively Q-switched Tm:YAP/BaWO 4 intracavity Raman laser

We report an intracavity Raman laser based on BaWO(4) Raman conversion in a diode-pumped actively Q-switched Tm:YAP laser for the first time. With an incident diode power of 17.5 W and a pulse repetition rate of 1 kHz, the maximum average output powers of 880 mW and 306 mW for the fundamental laser at 1.94 μm and the first Stokes laser at 2.36 μm were obtained, respectively. The pulse width and pulse energy of the first Stokes laser were 14.1 ns and 0.31 mJ, respectively. The Raman gain coefficient of the BaWO(4) crystal was estimated to be 1.1 cm/GW at 1.94 μm.

Orthogonally polarized dual-wavelength single-longitudinal-mode Tm,Ho:LLF laser

We first report a diode-pumped continuous wave orthogonally polarized dual-wavelength single-longitudinal-mode laser with a single c-cut Tm,Ho:LuLiF₄ laser crystal. The simultaneous dual-wavelength single-longitudinal-mode laser near 2 μm is realized by using two uncoated intracavity Fabry-Perot etalons. The output wavelengths are 2064 nm in π-polarization and 2066 nm in σ-polarization respectively, which are orthogonal to each other. At the absorbed pump power of 1 W, the maximum single-longitudinal-mode output powers at 2064 and 2066 nm are 76 and 32 mW respectively. The orthogonally polarized dual-wavelength single-longitudinal-mode laser is possible to be applied to the 2 μm differential absorption lidar and the generation of THz radiation.

Diode-pumped passively Q-switched dual-wavelength c-cut Tm,Ho:LLF laser at 2 μm

A compact diode-end-pumped passively Q-switched dual-wavelength c-cut Tm,Ho:LuLiF4 laser with a Cr:ZnS crystal as the saturable absorber is demonstrated for the first time, to the best of our knowledge. The maximum dual-wavelength average output power of 60 mW is obtained at 2065 and 2067 nm for the output coupler transmission of 5%, when the absorbed pump power is 2 W. The pulse width and pulse energy are about 54 ns and 6.5??J respectively, and are nearly independent of the absorbed pump power. The pulse repetition frequency can be tuned between 3 and 8.8 kHz by changing the absorbed pump power between 0.67 and 1.8?W. Furthermore, the influence of output coupler transmission on the laser performance is also investigated.

Diode-pumped Tm:YAP/YVO4 intracavity Raman laser

The laser performance based on YVO4 Raman conversion in a diode-pumped actively Q-switched Tm:YAP laser is demonstrated for the first time. With an incident diode power of 10.9 W and a pulse repetition rate of 1 kHz, the average output powers for the first Stokes laser at 2.4 μm is about 270 mW.

Polarization switching and optical bistability in the diode-pumped Tm,Ho:LLF laser

We first report on the polarization switching and optical bistability in the Tm,Ho:LLF laser. In the free-running operation, the switching of the π-polarization at 2069 nm and σ-polarization at 2066 nm are experimentally observed. By adjusting the tilting angle of an intracavity etalon, the orthogonally polarized dual-wavelength single-longitudinal-mode laser is obtained at 2054 and 2066 nm, and the π-polarized and σ-polarized single wavelength single-longitudinal-mode laser is obtained at 2057 and 2063 nm, which all show evident optical bistability.