X. W. Fan

Symmetric and short green-pulse generation by doubly Q-switched Nd:YVO4 laser

A compact diode-pumped doubly Q-switched extracavity frequency-doubled Nd:YVO4/KTP green-pulse laser was demonstrated, using both an acoustic-optic (AO) modulator and a GaAs saturable absorber in a simple flat-flat cavity. The green laser can generate a more symmetric and shorter pulse when compared with purely AO and passively Q-switched lasers. A peak power of 7.54 kW with the corresponding pulse width of 3.2 ns has been achieved with the incident pump power of 7.76 W and fp = 15 kHz. A reasonable analysis about the experimental results has been given.

An Intermittent Oscillation Dual-Wavelength Diode-Pumped Nd:YAG Laser

An alternately intermittent oscillation technique was proposed and an intermittent oscillation dual-wavelength diode side-pumped solid-state laser has been set up. The model of rate equations of intermittent oscillation dual-wavelength laser has been considered. By this means, the population inversion was distributed efficiently, mode competition of both laser lines can be avoided, the effect resulted from the accuracy of the coating process can be reduced and the stable output of dual-wavelength was easily obtained. What is more, for different operation condition, the ratio of the output powers can be controlled by changing the delay time, so it is very beneficial to all-solid-state RGB lasers.

High-power passively Q-switched mode-locking Nd:GdVO4 laser with LT-InGaAs saturable absorber

The generation of passively Q-switched mode-locking (QML) pulse has been obtained from a diode-pumped Nd:GdVO4 laser with a LT-InGaAs wafer as saturable absorber as well as output coupler. Under the incident pump power of 10 W, an average output power of QML was 1.8 W with a Q-switched repetition rate of 280 kHz. The pulse duration of Q-switched pulse is about 160 ns and mode-locked pulse within the Q-switched envelope had a repetition rate of 410 MHz. It is indicated that the present LT-InGaAs is a very promising device in the field of mode locking solid-state laser, and we are sure that it will be complete pure cw mode locking with single beam output easily after further optimizing in the parameter such as saturation fluence, modulation depth, recovery time and damage threshold in semiconductors.

Simultaneous generation of UV at 411 nm and red at 671 nm in a dual-structure periodically poled LiTaO3 crystal

A dual-color laser of red at 671 nm and ultraviolet (UV) at 411 nm was generated from dual-wavelength fundamental waves at 1342 and 1064 nm with a single periodically poled LiTaO3 (PPLT) optical superlattice. The PPLT sample used consists of two segments in a series: the first segment has a period of 14.55 μm for the second-harmonic generation (SHG) of 1342 nm and the second segment has periods of around 10.3 μm for the generation of UV light by sum-frequency mixing (SFG) of 1064 and 671 nm. An average output power of 3 and 79 mW for UV and red, respectively, has been obtained.

Broad spectral pulse operation of 2 μm Tm:YAP laser based on reflection-type carbon nanotube absorber

We demonstrated the first use of reflection-type single-walled carbon nanotube (RSWCNT) as a saturable absorber in the Q-switched mode-locking (QML) of a diode pumped Tm:YAP operating at 2 μm. The spectrum of the QML laser is centered at 1.97 μm with a broad spectral region of 36 nm. At the incident pump power of 10.33 W, as high as 432 mW average output power was produced in QML laser. The repetition rate of the mode-locked pulse inside the Q-switched envelope was 158 MHz. The dependence of the operational parameters on the pump power was also investigated experimentally.

Passively mode-locked Yb:LYSO laser with a reflection type single-walled carbon absorber

Passively diode-pumped Yb:LuYSiO5 (Yb:LYSO) laser mode locked by reflection-type single walled carbon nanotubes saturable absorber (RSWCNT-SA) is reported for the first time. Under the absorbed pump power of 13.23 W, continuous wave (CW) mode-locked pulses were generated with the maximum average output power of 157 mW. We obtained pulses as short as 4.0 ps around a center wavelength of 1038.3 nm. The peak power and the single pulse energy of the mode-locked laser were 0.38 kW and 1.52 nJ, respectively.

Passive mode-locking Yb3+:Sc2SiO5 laser at 1040 nm with SESAM

Passive mode locking of the new crystal Yb3+:Sc2SiO5 (Yb:SSO) laser at 1040 nm in a w-type cavity is reported for the first time to our knowledge. The laser operated at a repetition frequency of 94 MHz. A pulse duration of 4.2 ps was produced with an average power of 543 mW and a highest pulse energy of 5.7 nJ, corresponding it’s maximum peak power can reach to 1.4 kW.

Generation of UV radiation at 335.5 nm based on frequency-quadrupling of a diode-pumped Nd:YVO 4 laser

The generation of ultraviolet (UV) light at 335.5 nm based on frequency quadrupling of a diode-end-pumped Q-switched Nd:YVO4 laser at 1342 nm was demonstrated. KTP crystal was used for generation of wavelength of 671 nm by intracavity doubling and LBO (BBO) crystal was exploited for the subsequent external fourth harmonic generation (FHG). With 6.3-W absorbed pump power and 10-kHz frequency repetition rate, the UV output power of 35 and 63 mW were obtained by using LBO and BBO as frequency quadrupling nonlinear crystals, respectively. The experimental results show that the conversion efficiency (red-UV) of 6.4% for BBO crystal is higher than that of 3.5% for LBO crystal, but the UV beam quality obtained by LBO crystal is better than by BBO crystal.

LD side-pumped intracavity frequency-doubled high power Nd: YAG green laser based on acousto-optic Q-switch

A highly efficient and high power green laser generated by intracavity frequency doubling of a diode-sidepumped Q-switched Nd: YAG laser has been demonstrated. In the simple L-shaped cavity geometry, the maximum green output power of 28.5 W was obtained with a pulse width of 95 ns at a pulse repetition rate of 10 kHz by using a LBO crystal for frequency doubling, corresponding to a conversion efficiency of 11% from diode pump power to pulse green power. At a pulse repetition rate of 1. kHz, 6.9 mJ of pulse energy, 25 ns of pulse duration and 276 kW of peak power were obtained.

Continuous transform of transverse modes and transitional status analysis in solid-state laser.

With the agility of cavity control in solid-state-laser, we report abundant experimental phenomena of relatively complete Laguerre-Gaussian (LG) transverse multimodes transformation process including both stable and transitional status in a diode pumped Nd:YVO4 microcavity laser. Cavity structure, absorber, pump power, etc, synthetically have been found to contribute such abundant generation of patterns.