Zhenguo Wu

Simultaneous dual-wavelength operation of Nd:YVO 4 self-Raman laser at 1524 nm and undoped GdVO 4 Raman laser at 1522 nm

A diode-pumped, actively Q-switched dual-wavelength laser employing Nd:YVO(4) self-Raman emission at 1524 nm and undoped GdVO(4) Raman emission at 1522 nm is demonstrated. With a pump power of 21.5 W and pulse repetition frequency of 20 kHz, a maximum dual-wavelength output power of 1.62 W was obtained, comprising a 0.54 W, 1522 nm Raman component and 1.08 W, 1524 nm self-Raman component. The corresponding dual-wavelength Raman pulse width was 5.6 ns. The experimental results indicate that this laser, with quite small wavelength separation, was effective by virtue of simultaneous self-Raman and Raman shifts.

1st-Stokes and 2nd-Stokes dual-wavelength operation and mode-locking modulation in diode-side-pumped Nd:YAG/BaWO 4 Raman laser

1st-Stokes and 2nd-Stokes dual-wavelength operation within a diode-side-pumped Q-switched Nd:YAG/BaWO(4) intracavity Raman laser was realized. Using an output coupler of transmission of 3.9% at 1180 nm and transmission of 60.08% at 1325 nm, the maximum output power of 8.30 W and 2.84 W at a pulse repetition rate of 15 kHz for the 1st Stokes and the 2nd Stokes laser were obtained, respectively. The corresponding optical conversion efficiency from diode laser to the 1st Stokes and 2nd Stokes laser are 5.0% and 1.4%, respectively. With the pump power of 209 W and a pulse repetition rate of 15 kHz, the 1st Stokes and the 2nd Stokes pulse widths were 20.5 ns and 5.8 ns, respectively. The stable simultaneous Q-switching and mode locking of the 2nd Stokes laser without mode locking component was obtained at the pump power of about 29~82 W. The estimated mode-locked pulse width was approximately 31 ps at the pump power of 50 W and a pulse repetition rate of 15 kHz.

Second-Stokes dual-wavelength operation at 1321 and 1325 nm ceramic Nd:YAG/BaWO 4 Raman laser

A diode-pumped, actively Q-switched second-Stokes dual-wavelength laser employing ceramic Nd:YAG as the gain medium and BaWO(4) as the Raman medium is demonstrated. The dual-wavelength Raman laser emission at 1321 and 1325 nm is based on the dual-wavelength fundamental laser emission at 1061 and 1064 nm. With a pump power of 18.4 W and pulse repetition frequency of 15 kHz, a maximum dual-wavelength output power of 1.67 W was obtained, comprising a 0.75 W, 1321 nm laser component and a 0.92 W, 1325 nm laser component. The corresponding dual-wavelength second-Stokes pulse width was 2.9 ns.

Characteristics of the temperature-tunable Nd:YAG/YVO4 Raman laser.

We demonstrate a tunable crystalline Raman laser by varying the temperature of Raman crystal. Nd:YAG and YVO(4) crystals were selected as the laser and Raman gain media, respectively. The center wavelength of this Nd:YAG/YVO(4) Raman laser was tuned over a 0.49 nm range from 1175.76 to 1175.27 nm when the temperature of the Raman crystal was adjusted from 5 °C to 150 °C. The characteristics of this Raman laser including tunability, output power, and beam quality factors (M(2)) dependent on temperature were also studied in this paper.

Experiments with an intracavity BaTeMo2O9 Raman laser

A diode-side-pumped actively Q-switched intracavity Raman laser emitting at 1178 nm employing Nd:YAG as the gain medium and BaTeMo2O9 as the Raman medium is realized. With a pump power of 115 W and pulse repetition rate of 10 kHz, a maximum first-Stokes output power of 1.9 W is obtained. The corresponding diode-to-first-Stokes conversion efficiency is 1.7% and the first-Stokes pulse width is 35 ns. The preliminary experiments proved that an intracavity BaTeMo2O9 Raman laser is feasible.

Simultaneous Dual-Wavelength Generation at 1502 and 1527 nm in Ceramic Neodymium-Doped Yttrium Aluminum Garnet/BaWO4 Raman Laser

A diode-pumped, actively Q-switched eye-safe dual-wavelength laser employing ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG) as gain medium and BaWO4 as Raman medium is demonstrated for the first time to the best of our knowledge. The dual-wavelength Raman laser emission at 1502 and 1527 nm is based on the dual-wavelength fundamental laser emission at 1319 and 1338 nm. With a pump power of 17.3 W and pulse repetition frequency of 20 kHz, a maximum dual-wavelength output power of 0.82 W was obtained, comprising a 0.37 W, 1505 nm laser component and a 0.45 W, 1527 nm laser component.

Extracavity pumped BaWO 4 anti-Stokes Raman laser

The characteristics of a barium tungstate (BaWO(4)) anti-Stokes Raman laser at 968 nm are studied theoretically and experimentally. The BaWO(4) Raman resonator is pumped by a Q-switched Nd:YAG laser at 1064 nm with its axis tilted from the pumping laser axis. The non-collinear phase matching for the generation of the first anti-Stokes wave in the same BaWO(4) crystal is achieved. The output energy, temporal and spectral informations are investigated. At a pumping laser energy of 128 mJ, the anti-Stokes laser energy obtained is 2.2 mJ. The second Stokes radiation at 1324 nm as well as the first and the third Stokes waves at 1180 nm and 1509 nm is also generated at the same time. The maximum total Stokes energy output is 42.5 mJ. In the theory, the anti-Stokes laser intensity expression as a function of the pumping and the first Stokes laser intensities for the extracavity anti-Stokes Raman laser is deduced. The properties of the anti-Stokes Raman laser are simulated theoretically by solving the rate equations of the extracavity Raman laser and using the derived expression. The theoretical results are in good agreement with the experimental results.

A frequency-doubled Nd:YAG/KTP laser at 561 nm with diode side-pumping

An intracavity KTiOPO4 (KTP) frequency doubling laser emitting at 561?nm is achieved within a diode side-pumped acousto-optically Q-switched Nd:YAG laser. A compact convex?flat straight cavity is employed to achieve the compact configuration, where coatings are specially designed to suppress unwanted lines. At the pump power of 147?W and the pulse repetition rate of 10?kHz, the output power of 8.1 W was obtained at 561?nm. The corresponding optical-to-optical conversion efficiency is 5.5%. The pulse width of a 561?nm wave is 210?ns. The M2 factors are measured to be 15.5 and 17.5 in the horizontal and vertical directions respectively.

High-efficiency diode-pumped acousto-optically Q -switched 1123 nm ceramic Nd:YAG laser

A high-efficiency diode-pumped acousto-optically (AO) Q-switched ceramic Nd:YAG (cNd:YAG) laser operating at 1123 nm is demonstrated for the first time. With an incident pump power of 17.11 W and a pulse repetition rate of 30 kHz, an average output power of 5.86 W is obtained. The optical-to-optical conversion efficiency is 34.2% and the slope efficiency is 39.1%.

Extracavity pumped BaWO4 anti-Stokes Raman laser.

The characteristics of a barium tungstate (BaWO(4)) anti-Stokes Raman laser at 968 nm are studied theoretically and experimentally. The BaWO(4) Raman resonator is pumped by a Q-switched Nd:YAG laser at 1064 nm with its axis tilted from the pumping laser axis. The non-collinear phase matching for the generation of the first anti-Stokes wave in the same BaWO(4) crystal is achieved. The output energy, temporal and spectral informations are investigated. At a pumping laser energy of 128 mJ, the anti-Stokes laser energy obtained is 2.2 mJ. The second Stokes radiation at 1324 nm as well as the first and the third Stokes waves at 1180 nm and 1509 nm is also generated at the same time. The maximum total Stokes energy output is 42.5 mJ. In the theory, the anti-Stokes laser intensity expression as a function of the pumping and the first Stokes laser intensities for the extracavity anti-Stokes Raman laser is deduced. The properties of the anti-Stokes Raman laser are simulated theoretically by solving the rate equations of the extracavity Raman laser and using the derived expression. The theoretical results are in good agreement with the experimental results.