J. L. He

Diode-pumped continuous wave tunable and graphene Q-switched Tm:LSO lasers

We have investigated the lasing characteristics of Tm:LSO crystal in three operation regimes: continuous wave (CW), wavelength tunable and passive Q-switching based on graphene. In CW regime, a maximum output power of 0.65 W at 2054.9 nm with a slope efficiency of 21% was achieved. With a quartz plate, a broad wavelength tunable range of 145 nm was obtained, corresponding to a FWHM of 100 nm. By using a graphene saturable absorber mirror, the passively Q-switched Tm:LSO laser produced pulses with duration of 7.8 μs at 2030.8 nm under a repetition rate of 7.6 kHz, corresponding to pulse energy of 14.0 μJ.

A compact passively Q-switched intra-cavity frequency doubled Nd:YAG/Cr4+:YAG composite crystal green laser

A compact diode-end-pumped passively Q-switched intra-cavity frequency doubled Nd:YAG/Cr4+:YAG composite crystal laser was demonstrated. The pulsed laser at 532 nm was produced and the dependence of the average out power, pulse width and pulse repetition rate on incident pump power were measured. Under the pump power of 14 W, the minimum pulse width of 3.5 ns with repetition rate of 27.5 kHz was obtained, corresponding single-pulse energy of 18 μJ and peak power of 5.3 kW.

Directly LD-pumped passively Q-switched YVO4-Nd:YVO4 laser at 1.34 μm with a V3+: YAG saturable absorber

The performance of a directly LD-pumped passively Q-switched YVO4-Nd:YVO4 laser at 1.34 μm with a V3+:YAG saturable absorber was demonstrated for the first time to the best of our knowledge. The average output power of 580 mW was obtained at the pump power of 8.8 W, corresponding to the optical conversion efficiency of 6.6% and slope efficiency of 11%. The minimum pulse width was 280 ns with the pulse repetition rate of 230 kHz, which was attained with a T = 5.6% output coupler at the pump power of 8.8 W.

Passively Q-switched Nd:Sc 0.2 Y 0.8 SiO 5 dual-wavelength laser with the orthogonally polarized output

We have demonstrated a laser-diode pumped continuous-wave (CW) and passively Q-switched laser with a Nd:Sc(0.2)Y(0.8)SiO(5) (Nd:SYSO) crystal for the first time. In the CW operation, the laser was found to oscillate in tri-wavelength regime at 1074.8 nm, 1076.6 nm and 1078.2 nm, respectively. The maximum CW output power of 1.96 W was obtained, giving an optical-to-optical conversion efficiency of 35% and a slope efficiency of 39%. Using either Cr(4+):YAG or V(3+):YAG crystal as saturable absorber, stable passively Q-switched laser was obtained at dual-wavelength of 1074.8 nm and 1078.2 nm with orthogonal-polarization. The maximum average output power, pulse repetition rate, and shortest pulse width were 1.03 W, 50 kHz, and 24 ns, respectively. The passively Q-switched dual-wavelength laser could be potentially used as a source for generation of terahertz radiation.

12-W red light generation by frequency-doubling Q-switched Nd:YAG laser

By using a 15 mm-long type I phase-matching LBO crystal, a maximum quasi-continuous wave red laser output power of 12 W has been obtained by intra-cavity second-harmonic generation (SHG) in a compact acousto-optically Q-switched diode-side-pumped Nd:YAG laser. The corresponding optical-optical conversion efficiency is 6.6%. The power instability at the maximum output power is observed to be less than 4.62% during half an hour. The beam quality factor M2 is measured to be 9.9 ± 1.0 by the knife-edge method. The spectrum of the red radiation is also measured and discussed.

A tri-wavelength synchronous mode-locked Nd:SYSO laser with a semiconductor saturable absorber mirror

We report on the generation of passive mode locking of a Nd:Sc0.2Y 0.8SiO5 (Nd:SYSO) laser using a semiconductor saturable absorber mirror. Linear polarized, tri-wavelength synchronous mode-locked pulses were obtained for laser emissions at 1075.55, 1076.80 and 1078.20 nm. An interference pattern was observed in the autocorrelation trace, the beat pulse had a repetition rate of 0.345 THz and the beat pulse width was 646 fs. Numerical simulation was conducted to clarify the formation of the autocorrelation trace.

Highly efficient intracavity frequency doubling 532-nm laser based on the gray tracking resistance KTP crystal

Based on the gray tracking resistance (GTR) KTP crystals, the performance of a high efficient and compact intracavity frequency doubling 532 nm laser was investigated. The gray tracking test indicated that the KTP used in our experiment had good resistance to the gray tracking. The absorption coefficient of this GTR-KTP at 1064 and 532 nm were measure to be 5 × 10−3%/cm and 0.2%/cm, respectively. The maximum average output power of 40.6 W at 532 nm was obtained at the repetition frequency of 10 kHz for the 10 mm long GTR-KTP, which corresponded to 22.6% pump-to-green conversion efficiency. The effective conversion efficiency from the Q-switched 1064 nm to the green power at 10 kHz repetition rate was as high as 86.4%.

High beam quality and compact diode end-pumped Nd:YVO4 slab laser with a hybrid resonator

A compact, high power and high beam quality diode-end-pumped CW Nd:YVO4 slab 1064 nm laser with a hybrid resonator is demonstrated. The maximum output power of 23.0 W is obtained under the pump power of 66.7 W, which gives the slope efficiency and optical conversion efficiency of 52.0 and 34.0%, respectively. The beam quality M2 factors are measured to be 1.5 in the unstable direction and 1.7 in the stable direction. The power stability of the LD end-pumped slab laser at an output power of 19 W is measured to be 0.7% for half an hour operation.

Diode-pumped passively Q-switched and mode-locked Nd:GGG laser at 1.3 μm with V3+:YAG saturable absorber

Using V3+:YAG crystal as the saturable absorber, a diode-pumped passively Q-switched and mode-locked Nd:GGG laser operating at 1.3 μm is realized for the first time. The mode-locking modulation depth of nearly 100% has been achieved. The maximum output power and the single Q-switched pulse energy are 410 mW and 8.3 μJ. The mode-locked pulse inside the Q-switched pulse has a repetition rate of 349 MHz, and its average pulse width is estimated to be about 750 ps.

2 ns-pulse, compact and reliable microchip lasers by Nd:YAG/Cr4+ YAG composite crystal

A compact diode-end-pumped passively Q-switched composite Nd:YAG/Cr4+:YAG laser was demonstrated in this paper. At the incident pump power of 11.8 W, the shortest pulse width of 2.05 ns was obtained, corresponding to average output power of 1.15 W and repetition rate of 17.1 kHz. The single-pulse energy and peak power were estimated to be 67.3 μJ and 32.8 kW, respectively.