Dingzhong Yang

Compact dual-wavelength Nd:GdVO 4 laser working at 1063 and 1065 nm

We report a compact diode-laser pumped Nd:GdVO(4) laser with stable dual-wavelength output at 1063 nm and 1065 nm simultaneously. Two types of resonant cavity configurations were presented to support the stable dual-wavelength operation of the laser. Using a polarization beam splitter(PBS) included T-shaped cavity, we obtained a total power output over 5 W in two orthogonal polarized beam directions with 4 W in sigma polarization (1065.5 nm) and 1 W in pi polarization (1063.1 nm). By combining a half-wave-plate with the PBS in the laser cavity, a new configuration favoring one beam direction dual-wavelength output with same polarization direction was realized. A phenomenon of further line splitting was observed in both 1065 nm and 1063 nm.

High-power PPMgLN-based optical parametric oscillator pumped by a linearly polarized, semi-fiber-coupled acousto-optic Q-switched fiber master oscillator power amplifier

We have experimentally demonstrated a periodically poled magnesium-oxide-doped lithium niobate (PPMgLN)-based, fiber-laser-pumped optical parametric oscillator (OPO) generating idler wavelength of 3.82 μm. The pump fiber laser was constructed with a linearly polarized, semi-fiber-coupled acousto-optic Q-switched fiber oscillator and a polarization-maintaining fiber amplifier with pulse duration of 190 ns at the highest output power. The OPO was specifically configured in single-pass, singly resonant linear cavity structure to avoid the damage risk of the pump fiber laser, which is always a serious issue in the fiber-laser-pumped, double-pass, singly oscillating structured OPOs. Under the highest pump power of 25 W, an idler average output power of 3.27 W with one-hour peak-to-peak instability of 5.2% was obtained. The measured M2 factors were 1.98 and 1.44 for horizontal and vertical axis, respectively. The high power stability and good beam quality demonstrated the suitability of such technology for practical application.

A fiber laser pumped dual-wavelength mid-infrared optical parametric oscillator based on aperiodically poled magnesium oxide doped lithium niobate

We report a fiber laser pumped dual-wavelength mid-infrared optical parameter oscillator (OPO) based on an aperiodic optical superlattice (AOS) structure. An aperiodically poled MgO-doped lithium niobate wafer was designed and fabricated as the nonlinear crystal for the OPO. Using a linearly polarized pulsed Yb fiber laser at 1.064??m as the pump source, mid-infrared emissions at 3.3 and 3.8??m were obtained simultaneously from the OPO. The total output power at the idler wavelengths of 3.3 and 3.8??m reached 3.07?W under the maximum pump power of 27?W. The pump-to-idler conversion efficiency was 11.4% with a ratio of about 1.2:1 for 3.3??m and 3.8??m.

Fiber laser pumped high power mid-infrared laser with picosecond pulse bunch output

We report a novel quasi-synchronously pumped PPMgLN-based high power mid-infrared (MIR) laser with picosecond pulse bunch output. The pump laser is a linearly polarized MOPA structured all fiberized Yb fiber laser with picosecond pulse bunch output. The output from a mode-locked seed fiber laser was directed to pass through a FBG reflector via a circulator to narrow the pulse duration from 800 ps to less than 50 ps and the spectral FWHM from 9 nm to 0.15 nm. The narrowed pulses were further directed to pass through a novel pulse multiplier through which each pulse was made to become a pulse bunch composing of 13 sub-pulses with pulse to pulse time interval of 1.26 ns. The pulses were then amplified via two stage Yb fiber amplifiers to obtain a linearly polarized high average power output up to 85 W, which were then directed to pass through an isolator and to pump a PPMgLN-based optical parametric oscillator via quasi-synchronization pump scheme for ps pulse bunch MIR output. High MIR output with average power up to 4 W was obtained at 3.45 micron showing the feasibility of such pump scheme for ps pulse bunch MIR output.

High Power Efficient 3.81

We experimentally demonstrated a high power mid-infrared optical parametric oscillator that was pumped by a linearly polarized, pulsed Ytterbium-doped fiber laser. Cascaded parametric conversion was realized to obtain a higher conversion efficiency from the pump of 1.06 μm to the expected idler ~ 3.8 μm. A monolithic aperiodically poled magnesium-oxide doped lithium niobate was designed to compensate the phase mismatches of the nonlinear conversions from the pump to idler and the primary signal to idler simultaneously. The highest idler output power of 4.35 W at 3.81 μm was obtained under the pump power of 24.8 W at 1063.5 nm with pump-to-idler conversion efficiency of 17.5% and slope efficiency of 21.3%.

\mu{\rm m}

We report an acousto-optic Q-switched Nd:GdVO4 laser pumped flexibly tunable cascaded optical parametric oscillator (OPO) based on two separate multi-channel periodically poled magnesium oxide doped Lithium Niobate (PPMgLN). Even under lower pump power, long wavelength parametric output was found to be more easily generated than in single stage OPO. A cascaded idler output at 5.075 μm was found to be generated. A convenient method to monitor the occurring of the cascaded parametric process was also presented by measuring the spectrum of sum-frequency generation of the pump power and the cascaded signal power.

Emission From a Fiber Laser Pumped Aperiodically Poled Cascaded Lithium Niobate

A high-energy PPMgLN optical parametric oscillator (OPO) pumped by a E-O Q-switched Nd:YAG laser working at 1.064 μm was successfully illustrated. A maximum output pulse energy of 3.4 mJ was obtained with a pump threshold of 1.5 mJ and a slope efficiency of 30% around room temperature. The OPO output signal and idler wavelength were 1552 and 3384 nm, respectively. The damage to the input surface of PPMgLN crystal was carefully observed with a damage threshold of 4.6 J/cm2.

Study on the spectral characteristics of the cascaded parametric conversion in a single cavity tandem multi-channel PPMgLNs-based optical parametric oscillator

We report, to the best of our knowledge, the first demonstration of stable pulse generation from a gain-switched Tm:YAP laser directly pumped with a modulated high power laser diode around 790 nm. A piece of Tm:YAP crystal (3% Tm3+ doping) 5 mm in diameter and 12 mm in length was used as the gain medium. To realize effective gain-switching pulse operation, the laser diode was modulated with suitable pulse repetition rates and corresponding pulse durations. Stable single pulse output was achieved with repetition rates from 1 to 20 kHz. By adjusting the cavity parameters, a maximum laser output power of 4.6 W was obtained under a pump power of 16 W with corresponding overall optical-to-optical conversion efficiency of 28.7%.