Fen Bai

Theoretical and experimental studies on output characteristics of an intracavity KTA OPO

An acousto-optically Q-switched Nd:YVO(4)/KTiOAsO(4) (KTA) intracavity optical parametric oscillator (OPO) is efficiently realized in singly resonated scheme. With an end-pumping diode power of 25.9 W, output signal (1535 nm) power of 3.77 W and idler power (3467 nm) of 1.18 W are obtained at a pulse repetition rate of 50 kHz. A rate-equation model is set up to simulate the output power and time characteristics of both signal and idler waves. And both the numerical and experimental results show that the idler pulse width is shorter than the signal one in a singly resonant OPO.

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.

A graphene passively Q-switched Nd:YAG ceramic laser at 1123 nm

A 1123?nm ceramic Nd:YAG laser passively Q-switched by graphene grown on SiC wafer was demonstrated. With a pump power of 8.1?W, an average output power of 332?mW was obtained, corresponding to an optical-to-optical conversion efficiency of 4.1% and a slope efficiency of 7.8%. The pulse width was 875.7 ns with a pulse repetition rate of 46.8?kHz.

Efficient 1.8 μmKTiOPO 4 optical parametric oscillator pumped within an Nd:YAG/SrWO 4 Raman laser

A 1.8 μm optical parametric oscillator (OPO) based on a noncritically phase-matched KTiOPO4 crystal is demonstrated. OPO and stimulated Raman scattering techniques are successfully combined in an acousto-optically Q-switched Nd:YAG/SrWO4 Raman laser. The device efficiently realizes three steps of conversion: from a laser diode wavelength of 808 nm to the fundamental wavelength of 1064 nm; next, to the Stokes wavelength of 1180 nm; and finally to the OPO signal wavelength of 1810 nm. With an incident diode power of 7.2 W and a pulse repetition rate of 15 kHz, an average signal power of 485 mW is obtained with a diode-to-signal conversion efficiency of 6.75%. The beam quality factors (M2) of the signal wave in both horizontal and vertical directions are measured to be 1.7±0.2. The numerical output power results of the system, the thermal lensing, and the stability parameter of the cavity are also discussed.

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.

Passively Q-Switched Nd:KLu(WO4)2 Laser at 1355 nm with Graphene on SiC as Saturable Absorber

A 1.3 µm passively Q-switched Nd:KLu(WO4)2 laser under direct 880 nm pumping is reported. Graphene on a silicon carbide is used as the saturable absorber. Stable Q-switched laser pulses are obtained at the central wavelength of 1355.3 nm. Under an absorbed pump power of 14 W, the average output power, pulse repetition rate and single pulse energy are 890 mW, 135 kHz, and 6.6 µJ, respectively.

Simultaneous Dual-Wavelength Operation of Nd-Doped Yttrium Orthovanadate Self-Raman Laser at 1175 nm and Undoped Gadolinium Orthovanadate Raman Laser at 1174 nm

A diode-pumped actively Q-switched Nd-doped yttrium orthovanadate self-Raman emission at 1175 nm and undoped gadolinium orthovanadate Raman emission at 1174 nm dual-wavelength laser is demonstrated. With the pump power of 20.5 W and pulse repetition frequency of 20 kHz, the maximum dual-wavelength output power of 1.52 W was obtained, which contained a 0.71 W 1174 nm Raman laser component and a 0.81 W 1175 nm self-Raman laser component. The corresponding dual-wavelength Raman pulse width was 14.8 ns. Experimental results indicated that the dual-wavelength Raman laser with a small wavelength separation was effectively realized through simultaneous self-Raman and Raman shift.