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A novel nonlinear frequency conversion process was demonstrated to realize the synchronized dual-wavelength emissions at 1534 and 1572 nm by the mixed optical parametric oscillation (OPO) conversion in gray-tracking-resistance KTP (GTR-KTP) and KTA crystals. Both the two crystals were inserted into the diode-pumped Nd:YAG/Cr4+:YAG fundamental resonator, with their Y axes perpendicular to each other. This could eliminate the competition of the two OPO processes in fundamental radiation. Furthermore, the ratio between the length of GTR-KTP and KTA has also been specially designed to satisfy the same OPO thresholds. The synchronized dual-wavelength lasing with the power ratio of 1:1 between 1534 and 1572 nm was successfully realized. At an incident LD pump power of 7 W, the maximum total output power of 460 mW was achieved, with the corresponding pulse width and repetition rate measured to be 3.9 ns and 5.5 kHz, respectively. This mixed conversion opens a new door for the multi-wavelength lasing.

Diode end-pumped continuous wave (CW) and passively Q-switched (PQS) laser performances of the mixed Nd:Gd0.33Lu0.33Y0.33VO4 crystal are investigated for the first time. At the pump power of 9 W, the highest output power is 3.66 W, with an optical conversion efficiency of 40.7% and a slope efficiency of 43.6%. For pulsed operation, the minimum pulse width of 9.2 ns with Cr4+:YAG as saturable absorber is attained with the repetition rate of 81.8 kHz, and the single pulse energy and peak power are estimated to be 9.78 J and 1.06 kW, respectively.

We report a passively mode-locked Yb:Y2Ca3(BO3)4 (Yb:CYB) laser with a partially reflective semiconductor saturable-absorber mirror. The minimum pulse duration of 244-fs with a repetition rate of ~ 55 MHz has been obtained at the central wavelength of 1044.7 nm (8.1 nm full width at half maximum (FWHM)). The measured average output power amounts to 261 mW under the absorbed pump power of 7.0 W. To our best knowledge, this is the first demonstration of a femtosecond Yb:CYB laser.

A simultaneous dual-wavelength eye-safe laser at around 1.9 and 1.7 μm based on only a single KTiOAsO4 (KTA) intracavity optical parametric oscillator (IOPO) is firstly reported. The dual-wavelength-IOPO is driven by an acousto-optic (AO) Q-switched Nd:YAG laser, which is simultaneously oscillated at the radiations of 1.3 and 1.06 μm. Within the KTA-IOPO cavity, the signal output waves of IOPO at the wavelength of 1.9 and 1.7 μm are pumped by the 1.3 and 1.06 μm radiations from Nd:YAG laser, respectively. With the laser diode pumped power of 100 W and the pulse repetition rate of 4 kHz, the maximum average output power of 1.3 W at 1895 nm with the pulse duration of 30 ns and that of 0.9 W at 1715 nm with the pulse duration of 18 ns are obtained. With different diode pump power, the central wavelength of IOPO signal light at 1.9 μm is tunable from 1850 to 1895 nm, while the other signal wave at 1.7 μm is from 1650 to 1715 nm.

The continuous wave (CW) and passively Q-switched Nd:Gd3AlxGa5-xO12 (Nd:GAGG) laser operation at 938 nm have been realized for the first time. The maximum CW output power of 0.44 W was obtained under the absorbed pump power of 8.54 W, corresponding to the slope efficiency of 7.8% and optical-to-optical efficiency of 5.2% respectively. A V3+:YAG saturable absorber crystal with the initial transmission of 97% was used for the passive Q-switching regime. The maximum average output power of 0.19 W was achieved with the minimum pulse width of 358 ns and Q-switched repetition rate of 116 kHz. The corresponding single pulse energy and pulse peak power were determined to be 1.6 μJ and 4.6 W, respectively.

The diode-pumped passively Q-switched and Q-switching mode-locked Yb:Y2Ca3B4O12 lasers with V:YAG as saturable absorber are demonstrated in this paper. In the Q-switched regime, an average output power of 150 mW is obtained under the absorbed pump power of 6.6 W; the pulse width is 46 ns with the pulse repetition rate of 11 kHz, corresponding to the single pulse energy and peak power of 14 μJ and 296 W, respectively. For the Q-switched mode locking, the average output power of 223 mW is obtained with a repetition rate of 112 MHz. Moreover, due to the reabsorption effect, the emission wavelengths vary evidently with the different operation situation.

A diode-pumped passively Q-switching mode-locked Nd:Gd0.5Y0.5VO4 laser at 1.34 μm using V3+:YAG as the saturable absorber has been demonstrated for the first time to the best of our knowledge. At the pump power of 7 W, the maximum average output power of 0.83 W and Q-switched pulse repetition rate of 140 kHz were obtained with absorber's initial transmission of 96%, with the corresponding Q-switched pulse energy estimated to be 6 μJ. The duration of mode-locked pulse within Q-switched envelop was estimated to be 750 ps with 333.3 MHz repetition rate.

High efficient CW lasers at 1064 nm and 1342 nm were realized in a compact diode-end-pumped Nd:YVO4 slab. The maximum 1064 nm output power of 22.5 W was obtained under the pump power of 56.0 W, corresponding to the maximum optical conversion efficiency and slop efficiency of 40.1% and 50.1%, respectively. When the pump power was 34.7 W, the maximum output power at 1342 nm was obtained to be 4.4 W. The corresponding slope efficiency and the optical conversion efficiency were 17.9% and 12.6%, respectively.

A diode-end-pumped passively Q-switched mode-locked Nd:GdVO4 laser operating at 1.34 μm by using the Co2+:LaMgAl11O19 (Co2+:LMA) as the saturable absorber in a Z-type cavity has been demonstrated in our experiment for the first time. The repetition rate of the Q-switched pulse envelop increases from 4.2 kHz to 17 kHz as the pump power increases from 3.8 W to 8.9 W, and a maximum Q-switched and mode-locked fundamental mode average output power of 126 mW is obtained. The mode-locked pulse inside the Q-switched pulse has a repetition rate of 114 MHz, and its average pulse width is estimated to be about 280 ps.

A high power, high stability, eye-safe intracavity optical parametric oscillator (IOPO) working at the signal wavelength of 1534 nm was demonstrated, in which a type of non-critically phase-matched KTiOAsO4 (KTA) crystals were pumped by a diode-side-pumped acousto-optically Q-switched Nd:YAG laser. When a 25 mm-long KTA crystal was employed, a maximum average output power of 5.35 W and the minimum pulse width of 3.71 ns were obtained at the maximum 808 nm pump power of 143 W and the repetition rate of 6 kHz, giving an optical-optical conversion efficiency of 31.1% between the signal light at 1534 nm and the fundamental light at 1064 nm. To our best knowledge, it's the highest conversion efficiency for the KTA IOPO driven by diode-side-pumped Nd-doped lasers. The single pulse energy and peak power were determined to be 892 μJ and 287 kW, respectively. The power instability at the maximum output power was observed to be less than 1.72% during one hour.

In this article, we demonstrated the acousto-optical Q-switching performance of a high-power diode-pumped Nd:GGG laser. The maximum average output power of 2.56 W was obtained at the repetition rate of 15 kHz, and the minimum pulse width of 21 ns was obtained under the pump power of 9.18 W, the peak power and the pulse energy were calculated to be 11.4 kW and 253.6 μJ. The conversion efficiency of the output power from CW to Q-switching operation was amounted to 60.8%.

In this article, we demonstrated the continuous wave (cw) performance of a high-power diode-pumped Nd:GGG laser. The maximum output power of 13.2 W was obtained under the incident pump power of 28.8 W, giving the optical conversion efficiency of 49.5% and the slope efficiency of 51.5%. And the intrinsic loss of Nd:GGG crystal was measured to be 0.86% cm-1 in our experiment.