Haiyong Zhu

Potential sodium D 2 resonance radiation generated by intra-cavity SHG of a c-cut Nd:YVO 4 self-Raman laser

Intra-cavity frequency doubling with 589 nm emission from a compact c-cut Nd:YVO4 crystal self-Raman laser was investigated. A 15-cm-length LBO with non-critical phase-matching cut (θ = 90°, ϕ = 0°) was used for efficient second-harmonic generation. At a pump power of 16.2 W and a pulse repetition frequency of 40 kHz, output power up to 2.15 W was achieved with a pulse width of 16 ns and a conversion efficiency of 13.3% with respect to the diode pump power. The center wavelength was measured to be 589.17 nm with a Half-Maximum-Full-Width of 0.2 nm, which was well in accordance with the sodium D2 resonance radiation.

Efficient RTP-based OPO intracavity pumped by an acousto-optic Q-switched Nd:YVO 4 laser

This Letter describes an intracavity pumped optical parametric oscillator (OPO) based on noncritical phase matching RbTiOPO4 (RTP) crystal driven by a laser diode end-pumping acousto-optic Q-switched Nd:YVO4 laser. Simultaneous efficient signal light at 1.6 μm and idler light at 3.1 μm outputs were obtained. At an incident pump power of 10.5 W and a Q-switching pulse repetition frequency of 60 kHz, 1.42 W at center wavelength of about 1619 nm and 0.38 W at 3108 nm were achieved, with the diode to OPO total output conversion efficiency up to 17.1%. The pulse width is about 6.5 ns for the signal light corresponding to the fundamental light at 1064 nm of about 10 ns. The spectral widths of the signal and idler light are narrower than 0.5 and 1.0 nm. The result shows that the RTP crystal is an efficient crystal to generate eye-safe and mid-infrared lights by making full use of noncritical phase matching.

Continuous-wave laser operation of Nd:LuAG ceramic with 4 F 3∕2 → 4 I 11∕2 transition

The diode-end-pumped continuous-wave Nd:LuAG ceramic lasers at 1064 nm and 1123 nm with 4F3∕2→4I11∕2 transition are here presented for the first time. For the 1064 nm laser operation, the output has been optimized using output couplers with different transmissions. A maximum output power of 8.3 W was achieved under an incident pump power of 20.4 W with a conversion efficiency of 40.7%. Replacing the output coupler based on reasonable coating design for 1123 nm oscillation, a continuous-wave laser with single-wavelength at 1123 nm was obtained with the same ceramic. At an incident pumped power of 20.4 W, an output power of 3.5 W was achieved with a conversion efficiency of 17.2%.

Laser operation of diode-pumped Er,Yb co-doped YAG ceramics at 1.6 μm

1.6 μm eye-safe emission of a diode pumped Er,Yb co-doped YAG ceramic laser is firstly demonstrated. Operation of the ceramic laser under different ceramic sample lengths, co-doping concentrations and control temperatures were experimentally investigated. A maximum output power of 222 mW was achieved at an absorbed pump power of 8.1 W, corresponding to a conversion efficiency of 2.74%. Laser emission at 1.05 μm for transition of the Yb(3+) ions was also studied on the same ceramic samples. The results clearly show the existence of resonantly energy transfer from the Yb(3+) ions to Er(3+) ions.

Multi-order Stokes output based on intra-cavity KTiOAsO 4 Raman crystal

We report efficient multi-Stokes Raman output of a KTiOAsO4 (KTA) crystal driven by a laser diode end-pumped acousto-optic Q-switched Nd:YAG laser. The Raman outputs of two x-cut KTA crystals, one with a length of 20 mm and the other one of 25-mm, were experimentally compared. Under an incident pump power of 10.9 W, a maximum output power of 1.12 W with a pulse width of 7.6 ns and a pulse repetition frequency of 15 kHz were obtained. The conversion efficiency and slope efficiency with respect to the incident diode pump power were 10.3% and 15.2%, respectively. The laser output contains multiple Raman Stokes lines with different spectral strengths that varied with the pump power.

Generation of 2-

We propose an experimental technique for efficient 2- μm light generation based on the intracavity noncritical phase matching optical parametric oscillator (OPO). Intra-cavity pumped by a diode pumped actively Q-switched Nd:YVO4 laser operating at 1.3 μm, we have achieved efficient 2093-nm signal beam emission making full use of noncritical phase matching KTA-OPO. At a diode pump power of 9.8 W and a Q-switching repetition rate of 30 kHz, a signal beam with a spectral linewidth of ~ 1 nm and an average power of 1.01 W have been obtained, giving a diode pump power to signal power conversion efficiency of 10.3%. The short pulse width of ~ 3.4 ns is achieved, which is much shorter than other approaches with Q-switched operation to generate 2-μm laser beams.

\mu{\rm m}

Intra-cavity sum frequency generation (SFG) of c-cut Nd:YVO4 self-Raman laser was investigated for the first time. A 4 × 4 × 10 mm3 KTP crystal with a type-II phase-matching cutting angle (θ = 83.4°, φ = 0°) was used for SFG between the fundamental light at 1066 nm and first-Stokes light at 1178 nm. The laser system with different curvature radii of output couplers and different pulse repetition frequencies were investigated. At a pump power of 14 W and pulse repetition frequency of 20 kHz, the average output power of yellow-green laser at 560 nm up to 840 mW was achieved, corresponding to a slope efficiency of 7.6% and a conversion efficiency of 6% with respect to diode pump power.

Light Based on a Noncritical Phase Matching OPO Technique

Efficient laser operation of Nd:Lu₂O₃ ceramic fabricated by Spark Plasma Sintering (SPS) was demonstrated. Transparent Nd:Lu₂O₃ ceramic was successfully fabricated by Spark Plasma Sintering and its laser experiment was done. On the ⁴F_3/2 to ⁴I_11/2 transition, the obtained maximum output is 1.25W at the absorbed pump power of 4.15W with a slope efficiency of 38% and two spectral lines at 1076.7nm and 1080.8nm oscillated simultaneously. The slope efficiency of 38% is near two times higher than the previously demonstrated SPSed Nd:Lu₂O₃ ceramic lasers. On the ⁴F_3/2 to ⁴I_13/2 transition, the laser operated at the wavelength of 1359.7nm and the maximum output of 200mW was obtained at the absorbed pump power of 2.7W.

LD End-Pumped c-Cut Nd:YVO(4)/KTP Self-Raman Laser at 560 nm

We report on the third Stokes light from a potassium titanyle arsenate (KTA) crystal with a Raman shift of 234 cm−1. A 25 mm long x-cut KTA crystal was intracavity pumped by an acousto-optic Q-switched Nd:Lu0.5Y0.5VO4 polarized laser at 1065 nm. The fundamental, first, second, and third Stokes lights oscillated and shared the same resonator, but only the third Stokes light at 1151 nm was output based on appropriate coated cavity mirrors. At an incident pump power of 8.2 W and a pulse repetition frequency of 15 kHz, an average output power of 430 mW and a pulse width of 4.7 ns were obtained, with the diode to Raman output conversion efficiency of 5.2%.

Efficient laser operation based on transparent Nd:Lu 2 O 3 ceramic fabricated by Spark Plasma Sintering.

We reported a compact self-cascaded KTA-OPO source for 2.6 μm coherent light generation. The OPO is driven in a diode end-pumped and Q-switched Nd:YVO4 laser cavity. Two OPO processes occurred in the same KTA crystal with non-critical phase matching. At an incident diode pump power of 8.7 W and a pulse repetition frequency of 60 kHz, the OPO can generate a maximum average output power of 445 mW at 2.59 μm. The slope efficiency was about 12.7%, and the power fluctuation was less than 8%. Therefore, the self-cascade OPO based on KTA offers a promise scheme for the rugged and compact mid-infrared 2.6 μm laser generation.