Xuebin Wan

Comparison of c-Nd:YVO4/YVO4 raman lasers and c-Nd:YVO4 self-Raman lasers

Raman lasers based on c-Nd:YVO4 crystals can generate 1178 nm Stokes line, which can be frequency-doubled to realize 589 nm sodium lasers. We make comparative experimental studies of c-Nd:YVO4/YVO4 Raman lasers and c-Nd:YVO4 self-Raman lasers. About these two kinds of lasers, the output characteristics of power, center wavelength and beam quality are measured and compared.

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.

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.

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.

Frequency-Doubled Nd:Gd3Ga5O12/BaWO4 Raman Laser Emitting at 589 nm

A frequency-doubled BaWO4 Raman laser is realized inside an acousto-optically Q-switched Nd:Gd3Ga5O12 laser end-pumped by a fiber-coupled diode laser. First-Stokes Raman laser at 1178.2 nm is obtained, and intracavity second-harmonic generation is then accomplished to generate the 589 nm emission. This laser line has potential application to realize sodium guide stars. Under an incident diode power of 8.84 W and a pulse repetition rate of 10 kHz, we obtain a 589 nm output power of 0.82 W. The pulse duration is 9 ns, which leads to a peak power of 9.1 kW.

Intracavity KTiOAsO4 optical parametric oscillator pumped by an actively Q-switched Nd:YAG laser

A KTiOAsO4 (KTA) intracavity optical parametric oscillator (IOPO) is achieved within a diode end-pumped acousto-optically Q-switched Nd:YAG laser. With a 25-mm-long X-cut KTA crystal, efficient parametric conversions to signal (1535 nm) and idler (3467 nm) waves are realized. At an incident diode power of 14.9 W, the highest output power of 1.83 W including 1.37 W of signal and 0.46 W of idler radiations are obtained at a repetition rate of 40 kHz, corresponding to a total optical-to-optical conversion efficiency of 12.3%. Rate equations model are used to simulate this system, and the theoretical results agree with the experimental ones.

Theoretical and Experimental Study on the Intracavity Optical Parametric Oscillator Pumped in a Raman Laser

A rate-equation-based model is established to describe the behavior of an intracavity optical parametric oscillator (OPO) pumped in an actively -switched Raman laser system. The intracavity photon densities and the initial population inversion density are assumed to be Gaussian distribution. These coupled rate equations are solved numerically. In the experiment, a laser diode end-pumped acousto-optically -switched KTP-OPO pumped by a Nd:YAG/ Raman laser is demonstrated. The output characteristics are studied carefully. And the experimental results about the average output power agree with the numerical solutions.

Theoretical and experimental studies on passively Q-switched KTiOAsO4 optical parametric oscillator

A passively Q-switched intracavity optical parametric oscillator based on KTiOAsO4 (KTA) crystal is studied theoretically and experimentally. The rate-equation-based theoretical model is established to describe the time evolutions of the population inversion density of the laser crystal, ground-state population density of the saturable absorber, fundamental photon density, signal photon density and the idler photon density. In the experiment, a laser diode-end pumped, passively Q-switched Nd:YAG/KTA IOPO with a Cr4+:YAG crystal as the saturable absorber is realized to verify this model. The characteristics including the output power, the pulse repetition rate, the pulse width and the beam quality were investigated for this OPO. The experimental results for the output power and the repetition rate agree with the theory well. And both results show that with same pumping level the idler pulse width is shorter than the signal one.

1.8 μm optical parametric oscillator based on KTiOPO4

A 1.8 μm optical parametric oscillator pumped by a diode end-pumped acousto-optically Q-switched Nd:YAG is demonstrated. A 30-mm-long KTiOPO4 crystal cut with an angle of θ = 59.4°, φ = 0° is employed as the OPO crystal. 685 mW signal laser at 1.8 μm is obtained at the diode pump power of 13 W and the pulse repetition rate of 25 kHz. Simultaneously, 265 mW idler emission at 2.6 μm is obtained. The corresponded diode-to-OPO conversion efficiency is 7.3%. The pulse width of the signal and idler wave are measured to be 4.5 and 2.5 ns, respectively. This gives a peak power of 6.1 and 4.2 kW, respectively.