Passively Q-switched a-cut Nd:GdVO4 self-Raman laser with Cr:YAG

A passively Q-switched a-cut Nd:GdVO₄ self-Raman solid-state laser with Cr:YAG saturable absorber was firstly demonstrated. The first Stokes at 1173 nm was successfully obtained. At the maximum incident pump power, the pulse width was about 1.8 ns and the repetition rate was 27.5 kHz. 586.5 nm yellow laser output was also realized by use of an LBO frequency doubling crystal.     

LD-end-pumped passively Q-switched Nd:YAG ceramic laser with single wall carbon nanotube saturable absorber

We report on a LD-end-pumped passively Q-switched Nd:YAG ceramic laser by using a novel single wall carbon nanotube saturable absorber (SWCNT-SA). The SWCNT wafer was fabricated by electric Arc discharge method on quartz substrate with absorption wavelength of 1064 nm. We firstly investigated the continuous wave (CW) laser performance and scattering properties of Nd:YAG ceramic sample. For the case of passively Q-switched operation, a maximum output power of 376 mW was obtained at an incident pump power of 8.68 W at 808 nm, corresponding to an optical–optical conversion efficiency of 4.3%. The repetition rate as the increase of pump power varied from 14 to 95 kHz. The minimum pulse duration of 1.2 μs and maximum pulse energy of 4.5 μJ was generated at a repetition rate of 31.8 kHz.     

Tunable repetition frequency passively Q-switched Tm,Ho:YLF laser with Cr:ZnS as a saturable absorber

We first report a tunable repetition frequency passively Q-switched 2053 nm Tm,Ho:YLF laser by tuning the tilt angle of the Cr:ZnS saturable absorber. When the pump power is 1.4 W, the pulse repetition frequency can be tuned from 1.6 to 19.4 kHz by changing the position of Cr²⁺:ZnS saturable absorber along the cavity axis. When the Cr²⁺:ZnS saturable absorber is near the Tm,Ho:YLF crystal, the repetition frequency can be tuned from 0.8 to 4.0 kHz by changing the tilt angle of the Cr²⁺:ZnS saturable absorber, furthermore, the pulse width and the pulse energy are near constants of 1.7 μs and 3.5 μJ, respectively.     

Passively Q-switched,high peak power Nd:YAG laser pumped by QCW diode laser

A Nd:YAG laser passively Q-switched by a Cr:YAG showed a high single pulse energy of 53.0 mJ and 5.1 MW peak power. The laser was pumped by quasi-continuous-wave diode bars from single side. The Q-switched pulse had optical-to-optical efficiency of 12% and average temporal duration of 10.4 ns when Cr:YAG with initial transmission of 9.0% was used. Intense pumping as well as very low initial transmission of the saturable absorber gave very high peak power.     

2 μm passive Q-switched mode-locked Tm3+:YAP laser with single-walled carbon nanotube absorber

We report the first demonstration, to our knowledge, of passive Q-switched mode-locking in a Tm³⁺:YAP laser, operating in the 2 μm broadly spectral region formed with a compact Z-flod cavity. A transmission-type single-walled carbon nanotube saturable absorber (SWCNT–SA) is used for the initiation of the pulse generation. The repetition rate of the Q-switched envelope was 60 kHz at the pump power of 8.6 W. The mode-locked pulses inside the Q-switched pulse envelope had a repetition rate of ～92 MHz. A maximum average output power of 761 mW was obtained. The dependence of the operational parameters on the pump power was also investigated experimentally.     

Diode-pumped Nd:YAG ceramic laser at 946 nm passively Q-switched with a Cr4+:YAG saturable absorber

We demonstrate a diode-pumped Nd:YAG ceramic laser with emission at 946 nm that is passively Q-switched by single-crystal Cr⁴⁺:YAG saturable absorber. An average output power of 1.7 W is measured under 18.4 W of incident power using an output mirror with transmission T=4%. The corresponding optical-to-optical efficiency is 9.2%. The laser runs at a pulse repetition rate of 120 kHz and delivers pulses with energy of 14 μJ and duration of 80 ns, which corresponds to a peak power of 175 W.     

A diode end-pumped passively Q-switched Nd:YAG/KTA Raman laser

A diode end-pumped passively Q-switched Nd:YAG/KTA intracavity Raman laser is presented. A KTA crystal with a size of 5 mm × 5 mm × 25 mm is used as the Raman active medium and its 234 cm^?1 Raman mode is employed to finish the conversion from 1064 nm fundamental laser to 1091 nm Raman laser. A 2 mm thick Cr⁴⁺:YAG crystal is used as the saturable absorber. With an LD pump power of 7.5 W, the first-Stokes power of 250 mW is obtained with a pulse repetition frequency of 14.5 kHz. The corresponding diode-to-Stokes conversion efficiency is 3.3% and the pulse energy is 17.2 μJ. Pulse width is measured to be 12.6 ns and peak power is 1.4 kW.     

Passively Q-switched diode-pumped Raman laser with third-order Stokes eye-safe oscillation

We demonstrate a passively Q-switched all-solid-state laser system with intracavity Raman frequency conversion to the eye-safe spectral region. Laser oscillation at the 1.064 μm wavelength with a pulse repetition rate of several kilohertz was provided by a Nd:YAG crystal and a Cr:YAG passive absorber. Third Stokes oscillations at the 1.599 and 1.494 μm wavelengths were obtained in Ba(NO₃)₂ and PbWO₄ crystals with output pulse energies of 5 μJ and 6 μJ, respectively. The results of the numerical simulation of the pulse dynamics are in good agreement with the experimental data.     

Femtosecond single-mode diode-pumped Cr:LiSAF laser mode-locked with single-walled carbon nanotubes

A low threshold Cr:LiSAF laser pumped with an inexpensive single-mode laser diode emitting 120 mW was passively mode-locked with a novel ultrafast saturable absorber mirror based on single-walled carbon nanotubes (SWCNT-SAM). Pulses as short as 122 fs were achieved, tunable across 14 nm. A second pump diode coupled in polarization allowed to shorten the pulse duration to 106 fs, with up to 24-mW output power.     

Diode-pumped doubly Q-switched Nd:Lu0.33Y0.37Gd0.3VO4 laser with an electro-optic modulator and a single-walled carbon nanotube saturable absorber

By simultaneously using an electro-optic (EO) modulator and a single-walled carbon nanotube saturable absorber (SWCNT-SA) in the cavity, a diode-pumped doubly Q-switched Nd:Lu_0.33Y_0.37Gd_0.3VO₄ (Nd:LuYGdVO₄) laser is demonstrated. At the incident pump power 11.43 W and f=2 kHz, the minimum pulse width 17.6 ns and the maximum pulse peak power 19,886 W can be obtained. The experimental results show that this doubly Q-switched Nd:LuYGdVO₄ laser can generate shorter pulse width and higher peak power compared to the singly Q-switched Nd:LuYGdVO₄ laser with only EO or SWCNT-SA.     

Passively Q-switched Tm,Ho:LuLiF4 laser with near constant pulse energy and duration

A compact diode-pumped passively Q-switched Tm,Ho:LuLiF₄ laser with a Cr:ZnS saturable absorber is demonstrated for the first time. The maximum average output power of 74 mW is achieved at the absorbed pump power of 1.5 W, and the threshold power is only 0.68 W. The laser operates at the wavelength of 2,055 nm and produces pulses with near constant duration of 1.2 μs and pulse energy of 13 μJ at the pulse repetition frequency from 1 to 5.2 kHz. The stable long-pulse laser can be used in laser lidar systems for accurate wind velocity measurements.     

Diode-pumped Q-switched and mode-locked Nd:Gd0.3Lu0.33Y0.37VO4 laser with EO modulator and single-walled carbon nanotube

By using both the single-walled carbon nanotube saturable absorber (SWCNT-SA) and the electro-optic (EO) modulator, the stably doubly Q-switched and mode-locked (QML) operation of Nd:Gd_0.3Lu_0.33Y_0.37VO₄ laser has been demonstrated. The QML laser characteristics such as the pulse width, single-pulse energy, etc., have been measured for different modulation frequencies of the EO modulator (f_e) and reflectivity (R) of output coupler. In comparison with the solely passively QML laser with SWCNT-SA, the experimental results show that the doubly QML laser can generate more stable and shorter pulses with higher pulse energy. At 9.24 W pump power, f_e=1 kHz and R=93.5%, the doubly QML laser has compressed the Q-switched envelope pulse width 88% and improved the mode-locked pulsed energy 55 times.     

A passively Q-switched diode pumped Yb:YAG microchip laser

A passively Q-switched diode pumped Yb:YAG microchip laser with Cr4+:YAG saturable absorber mirror is reported. The TEMoo laser pulses are obtained with 1,7-uJ pulse energy, 15-ns pulse width, 0.11-kW peak power, and a repetition rate of 2.2 kHz at 1049 nm. The doped concentration and dimension of Yb:YAG microchip crystal are 10 at.-% and 5×0.6 mm2, respectively.     

Doubly Q-switched GdVO4/Nd:GdVO4 laser with AO modulator and Cr4+:YAG saturable absorber under direct 879 nm diode pumping to the emitting level

In this letter, a doubly Q-switched 1.06 μm pulse laser with AO modulator and Cr⁴⁺:YAG saturable absorber by direct pumping grown-together composite GdVO₄/Nd:GdVO₄ crystal is demonstrated for the first time. Compared to purely AO Q-switching, the simultaneous use of AO Q-switch and Cr⁴⁺:YAG saturable absorber can generate shorter pulses and more symmetric temporal profiles. The thermal lens effect of laser crystal was analyzed.     

Improvement of stability and pulse energy in a diode-pumped dual-loss-modulated QML Nd:Lu0.2Y0.8VO4 laser with EO modulator and GaAs

The Q-switched and mode-locked (QML) performance in a diode-pumped Nd:Lu_0.2Y_0.8VO₄ laser with electro-optic (EO) modulator and GaAs saturaber absorber is investigated. In comparison with the solely passively QML laser with GaAs, the dual-loss-modulated QML laser with EO and GaAs can generate pulses with higher stability and shorter pulse width of Q-switched envelope, as well as higher pulse energy. At the repetition rate 1 kHz of EO, the pulse width of Q-switched pulse envelope has a compression of 89% and the pulse energy has an improvement of 24 times. The QML laser characteristics such as the pulse width, pulse peak power etc. have been measured for different small-signal transmittance (T₀) of GaAs, different reflectivity (R) of output coupler and modulation frequencies of the EO modulator (f_e). The highest peak power and the shortest pulse width of mode-locked pulses are obtained at f_e = 1 kHz, R = 90% and T₀ = 92.6%. By considering the influences of EO modulator, a developed rate equation model for the dual-loss-modulated QML laser with EO modulator and GaAs is proposed. The numerical solutions of the equations are in good agreement with the experimental results.     

Diode-pumped passively Q-switched intracavity frequency doubled Nd:GdVO4/KTP green laser

A compact diode-pumped passively Q-switched intracavity frequency-doubled Nd:GdVO₄/KTP green-pulse laser was demonstrated, using Cr⁴⁺:YAG as a saturable absorber in a simple flat–flat cavity. With a 5.9 W incident pump power, a passively Q-switched green laser was obtained with an average power of 397 mW, repetition rate of 40 kHz, and pulse width of 40 ns, when the initial transmission of Cr⁴⁺:YAG was 85%. The shortest pulse width of 30 ns, the highest green peak power of 696 W and the maximum pulse energy of 21 μJ were obtained when the initial transmission of Cr⁴⁺:YAG was 70%. Under CW green operation, we obtained 440 mW output power.     

Diode-pumped passively Q-switched Nd:LuVO4 laser at 916 nm

We demonstrate a passively Q-switched Nd:LuVO₄ laser at 916 nm by using a Nd, Cr:YAG crystal as the saturable absorber. As we know, it is the first time to realize the laser with a simple linear resonator. When the incident pump power increased from 14.6 W to 23.7 W, the pulse width of the Q-switched laser decreased from 24 ns to 21 ns. The pulse width was insensitive to the incident pump power in the experiment. The average output power of 288 mW with repetition rate of 39 kHz was obtained at an incident pump power of 22.5 W, with the optical-to-optical efficiency and slope efficiency 1.3% and 3.6%, respectively.     

Diode-pumped continuous-wave and passively Q-switched 1.06 μm YVO4/Nd:GdVO4 laser

In this letter, a diode-pumped continuous-wave and passively Q-switched 1.06 μm laser with a novel composite YVO₄/Nd:GdVO₄ crystal was demonstrated for the first time. Theoretical calculations showed that the temperature distribution in YVO₄/Nd:GdVO₄ crystal was lower than that in GdVO₄/Nd:GdVO₄ and Nd:GdVO₄ crystals under the same conditions. After optimizing the mode matching degree, a CW output power of 5.6 W of YVO₄/Nd:GdVO₄ laser was obtained at the incident pump power of 12 W when the output coupler with transmission of 30% was employed. Using Cr^4 +:YAG crystals with initial transmission (T₀) of 80% and 90% as saturable absorbers, the pulsed YVO₄/Nd:GdVO₄ laser characteristics were investigated. At the incident pump power of 12 W, the maximum average output power of 2.76 W and the maximum repetition rate of 189 kHz was achieved when T₀ = 90% Cr^4 +:YAG was used. The shortest pulse width was 28.1 ns when the initial transmission of the used Cr^4 +:YAG was 80%.     

Diode-pumped passively mode-locked Nd:Lu0.15Y0.85VO4 laser with a single-walled carbon nanotube saturable absorber

Diode-pumped passively mode-locked Nd:Lu_0.15Y_0.85VO₄ laser with a single-walled carbon nanotube saturable absorber was demonstrated for the first time, to our best knowledge. The laser generated 19-ps pulses with maximum output power of 902 mW for the incident pump power of 6.5 W at the central wavelength of 1064 nm, giving an optical conversion efficiency of 14%. The continuous wave mode-locking conditions of single-walled carbon nanotube saturable absorber were analyzed and discussed.     

基于多层石墨烯可饱和吸收体的被动调Q Ho∶YAG激光器

报道了2μm被动调Q的Ho∶YAG激光器,该激光器采用Tm~(3+)光纤激光器作为泵浦源,使用多层石墨烯作为可饱和吸收体。在连续波激光输出模式下,当泵浦功率为4.2 W时,获得了750 mW激光输出,输出激光中心波长为2.09μm,斜率效率为29.6%。在连续波激光器谐振腔中插入多层石墨烯可饱和吸收体并调整谐振腔,获得了脉冲激光输出。当泵浦功率为4.2 W时,获得最小脉冲宽度3.1μs、重复频率66.6 kHz的脉冲激光输出,其最大平均输出功率为170 mW,斜率效率为12.6%,光束质量因子M_x~2=1.15,M_y~2=1.12。