Numerical analysis of synchronously pumped solid-state Raman lasers.

Considering the spatial distribution of laser beams and phonon waves, the SRS coupling wave equations in the transient regime are derived and normalized for the first time. The synchronously pumped solid-state Raman laser is simulated numerically to investigate the influences of the cavity length detuning, output coupling rate, dispersion, Raman gain and dephasing time of Raman mode on laser performances. It is found that the intensive pulse compression of first Stokes laser in synchronously pumped solid-state Raman laser stems from pulse width gain narrowing and intensity oscillation effects. The cavity length detuning, dispersion, Raman gain and dephasing time considerably affect the pulse width gain narrowing and intensity oscillation processes. The theoretical results can help the design and optimization of synchronously pumped solid-state Raman laser to generate ultrafast Raman laser output efficiently.

Laser diode pumped, actively Q-switched, and mode-locked Nd:YAG/PbWO(4) Raman laser.

A compact laser diode pumped, actively Q-switched, and mode-locked Nd:YAG/PbWO(4) Raman laser is demonstrated. With the incident pump power of 9.11 W and pulse repetition frequency of 15 kHz, a maximum average output power of 1.003 W at 1178 nm was obtained and the corresponding conversion efficiency was 11%. A perfect stable mode-locking operation with the modulation depth of 100% was obtained and the corresponding mode-locking pulse width was less than 207 ps. The actively Q-switched and mode-locked Raman laser was theoretically analyzed and calculations were conducted using the fluctuation rate equation model.

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.

Investigation on LD end-pumped passively Q-switched c-cut Nd: YVO4 self-Raman laser.

The compact LD end-pumped passively Q-switched c-cut Nd:YVO4/Cr4+:YAG self-Raman laser is realized, and its output performance is investigated in detail. The maximum average output power at 1178nm is 800mW with the pulse repetition frequency of 44kHz and pulse width of 2.6ns, and the first Stokes conversion efficiency is 10.1%. The outputs of fundamental and first Stokes laser are found to be linearly polarized along the diagonals of the rectangular cross section of the c-cut Nd:YVO4 crystal, and the polarization mode competition is observed in the outputs of fundamental and first Stokes laser.

Theoretical and experimental study on passively Q-switched intracavity frequency-doubled solid-state yellow Raman lasers.

Normalized space-dependent rate equations of passively Q-switched intracavity frequency-doubled Raman lasers are deduced for the first time. The normalized rate equations are solved numerically to investigate the influences of the normalized variables on the yellow laser performance. The LD end-pumped passively Q-switched Nd:YAG/SrWO(4)/KTP/Cr:YAG yellow Raman laser is realized, and the maximum yellow laser output power is 350 mW with the incident pump power of 5.9 W with Cr:YAG of 85% initial transmission. The theoretical analysis and optimization are taken out for the experiment, and the theoretical results are in accordance with the experimental ones.

Gain improvement by internal laser cavity in Tm(3+)Yb(3+)-co-doped tellurite fiber amplifier pumped by 980-nm laser.

S-band Tm(3+)/Yb(3+) co-doped tellurite fiber amplifier pumped by a 980 nm laser diode is proposed and modeled taking into consideration of the energy transfer process from Yb(3+) to Tm(3+) and the laser cavity inside a co-doped fiber amplifier. S-band spectral gains for the co-doped fiber amplifiers are investigated. The results show that considerable gain improvement can be achieved by constructing 1050nm laser cavity inside the amplifier.

Passive Q-switching characteristics of Yb3+:Gd3Ga5O12 crystal.

The passively Q-switched laser characteristics of a quasi-three level Yb3+:Gd3Ga5O12 (Yb3+:GGG) crystal with Cr4+:YAG saturable absorbers are studied experimentally and theoretically. The pulse parameters under different experimental conditions are measured. Some characteristics different from those of a four-level system are found. In the theoretical aspect, taking into account the spatial distributions of the pump light and intracavity laser mode, the rate equations describing the single Q-switched pulse characteristics of a quasi-three-level system are obtained. The obtained theoretical results are in fair agreement with the experimental results. Some topics such as the influence of the pumping power, the selection of the pump beam size, the optimal combination of output coupler reflectivity and saturable absorber initial transmission, the influence of the excited absorption of the saturable absorber, are discussed.

Theoretical and experimental research on the multi-frequency Raman converter with KGd(WO4)2 crystal.

An efficient multi-frequency extracavity Raman laser for nanosecond pulses was realized by taking advantage of the anisotropic optical property of the KGd(WO4)2 crystal. The conversion efficiencies of the converter were investigated versus the pump pulse energy, pump polarization, and output coupling rate experimentally and theoretically. Based on the coupled radiation transfer equations, a theoretical model was deduced to predict the performance of solid-state extracavity Raman lasers. This model was solved numerically to analyze the operation of the extracavity Raman laser with the KGd(WO4)2 crystal, and the numerical results had a good agreement with the experimental ones.