1 mJ Passively Q-switched Nd:YAB laser using a V:YAG crystal

We describe the design and operation of a diode-pumped compact and efficient Nd:YAB laser operating at 1338 nm. We use a passive Q-switch V:YAG crystal to achieve 1 mJ Q-switched pulses at the laser output. The laser elaborated provides an average power of 1.5 W in the CW regime and 1 W in Qswitched mode with an optical efficiency of 15 and 10%, respectively. A 65 mm plano-concave cavity is formed with an output in the TEM₀₀ mode. At a pulse width of 15 ns, the achieved peak power is 66 kW.     

不同脉冲重复频率下抽运方式对全光纤声光调Q激光器性能的影响

在不同初始边界条件下数值求解描述全光纤声光调Q双包层光纤激光器的速率方程,得到前向抽运结构和后向抽运结构下激光器上能级粒子数在增益光纤中的分布,以及脉冲能量、平均功率、脉宽、光纤中储能与脉冲重复频率、抽运合束器对信号光透过率、抽运功率的相互关系.从谐振腔内放大自发辐射光的产生影响谐振腔损耗的角度分析仿真结果,并实验验证两种抽运方式对输出脉冲功率和脉冲宽度的影响.结果表明：不同脉冲重复频率下抽运方式会对全光纤声光调Q激光器性能产生显著影响,为获得较好的脉冲输出性能,在重复频率较低 关键词： 光纤激光器 Q')" href="#">声光调Q 抽运方式     

Continuous-wave and Q-switched Operation of a Tm,Ho:YAP ring laser

We demonstrated continuous-wave (CW) and Q-switched operation of a Tm,Ho:YAP ring laser at 77 K. The maximum CW output power of 2 W at 2130.7 nm was obtained under the incident pump power of 12 W, corresponding to a slope efficiency of 23% and an optical-to-optical efficiency of 16.7%. For the Q-switched regime the maximum output energy of 5 mJ with the pulse width of 160 ns at the repetition rate of 100 Hz was achieved, corresponding to a peak power of 31.25 kW.     

High-Power in-Band Pumped a-Cut Ho:Yap Laser

We report the continuous wave and acousto-optically Q-switched operation of an in-pumped a-cut Ho:YAP laser at room temperature. We obtained a continuous-wave output power of 17.2 W at 2118 nm under an absorbed pump power of 29.8 W, corresponding to a slope efficiency of 63.2 %. For the Q-switched mode, we achieved a maximum pulse energy of about 1.7 mJ and a minimum pulse width of 24 ns at a repetition rate of 10 kHz, resulting in a peak power of 70.8 kW.     

The characteristics of diode-pumped acousto-optic Yb:Y2Ca3B4O12 laser for Q-switching and Q-switched mode-locking

Q-switching and Q-switched mode-locked Yb:Y₂Ca₃B₄O₁₂ lasers with an acousto-optic switch are demonstrated. In the Q-switching case, an average output power of 530 mW is obtained at the pulse repetition rate of 10.0 kHz under an absorbed pump power of 6.1 W. The minimum pulse width is 79 ns at the repetition rate of 1.7 kHz. The pulse energy and peak energy are calculated to be 231 μJ and 2.03 kW, respectively. In the Q-switched mode-locking case, the average output power of 64 mW with a mode-locked pulse repetition rate of 118 MHz and Q-switched pulse energy of 48 μJ is generated under the absorbed pump power of 6.1 W.     

Doubly <Emphasis Type="Italic">Q</Emphasis>-Switched Nd:YAG Ceramic Laser

Using simultaneously both an acousto-optic (AO) modulator and a Cr⁴⁺:YAG saturable absorber in the cavity, we demonstrate for the first time the performance of a diode-pumped doubly Q-switched Nd:YAG ceramic laser. In contrast to purely acousto-optic Q-switched laser, this doubly Q-switched laser can generate shorter and more symmetric pulses. At an absorbed pump power of 10 W and a repetition rate of 20 kHz, the pulse width is compressed to 30 and 25 ns, respectively.     

Narrow pulse width and high power passively Q-switched Nd3+:Gd3Ga5O12 laser with Cr4+:YAG saturable absorber

A compact, diode-pumped passively Q-switched Nd³⁺:Gd₃Ga₅O₁₂ (Nd:GGG) laser with Cr⁴⁺:YAG saturable absorber has been successfully demonstrated. Stable Q-switched pulses with pulse energy of 100 ??J and high peak power of 14 kW have been obtained. The pulse width was as short as 7 ns with low repetition rate of 10 kHz. The dependence of pulse width, pulse repetition rate, pulse energy and pulse peak power on pump power have been measured respectively. Experimental results reveal that the Nd:GGG crystal with Cr⁴⁺:YAG saturable absorber is suitable for narrow pulse width and high power passively Q-switched lasers.     

A Tm:YLF End-Pumped Acousto-Optic <Emphasis Type="Italic">Q</Emphasis>-Switched Ho:YAG Laser

We report an acoustic Q-switched Ho:YAG laser end-pumped by a 1,908 nm Tm:YLF laser. The doping concentration of Ho:YAG crystal is 2 at.%, and dimensions ø5×20 mm. We measure the pulsedlaser output characteristics of the Ho:YAG laser at different repetition rates (RF). Under optimum experimental conditions, the high-power 2.1 μm output power reaches 4.17 W at a given pump power of 13.25 W and repetition frequency of 8.0 kHz. For a slope efficiency of 16.88%, the corresponding optical-to-optical conversion efficiency reaches 31.47%. We obtain a minimum single pulsed energy of 7.36 mJ and a pulse width of 52.8 ns at a pump power of 10.52 W and repetition rate of 0.5 kHz, with a peak power of 139 kW.     

<Emphasis Type="Italic">Q</Emphasis>-Switched Yb-Doped Fiber Ring Laser with a Saturable Absorber Based on a Graphene Polyvinyl Alcohol Film

We propose, design, and demonstrate a Q-switched ytterbium-doped fiber laser (YDFL) employing a thin graphene polyvinyl alcohol (PVA) film as a passive saturable absorber (SA). The graphene is synthesized by electrochemical exfoliation of graphite at room temperature in 1% sodium dodecyl sulfate (SDS) aqueous solution. Graphene flakes obtained from the process are mixed with PVA solution as the host polymer to produce a thin film, which acts as a passive Q-switcher in the YDFL ring cavity. The laser generates a stable pulse operating at a wavelength of 1,076.4 nm with a threshold pump power of 73.7 mW. At a maximum 980 nm pump power of 113.6 mW, the YDFL generates an optical pulse train with a repetition rate of 25.53 kHz and a pulse width of 10 μs. The maximum pulse energy of 50.9 nJ is obtained at a pump power of 109.9 mW. A higher-performance Q-switched YDFL is expected to be achieved with optimization of the graphene saturable absorber and the laser cavity.     

Actively Q-switched intracavity frequency-doubled Nd:LuVO<Subscript>4</Subscript>/LBO green laser with an acousto-optic modulator

This work presents experimental results concerning an actively Q-switched intracavity frequency-doubled Nd:LuVO₄/LBO green laser with an acousto-optic modulator operated at the wavelength of 0.53 μm. The green average output power of 2.8 W was obtained at a pump power of 16.3 W and a pulse repetition rate of 20 kHz, resulting in an optical conversion efficiency of 17%. When the pulse repetition rate is operated at 5 kHz, the shortest pulse width and the highest peak power at 0.53 μm were measured to be 26.5 ns and 8.43 kW, respectively.     

Switching of the generation of nano/picosecond pulses in Nd:YAG laser with Pockels Q-switch

A method for switching the regime of single-frequency generation of nanosecond pulses to a train of picosecond pulses in the Nd:YAG laser with an electro-optic Pockels Q-switch without changing cavity elements is proposed. The single-frequency regime was provided by aligning an active element which played the role of a longitudinal cavity mode selector. The lasing spectrum was measured using a Fabry-Perot interferometer with simultaneous recording of pulse oscillograms.     

A 100 kHz Narrow-Pulse-Width Mid-Infrared Optical Parametric Oscillator Based on PPMgLN Crystal

We report a narrow pulse width optical parametric oscillator based on periodically poled MgO:LiNbO₃ (PPMgLN) with a high repetition rate under quasi-phase matched conditions. When the maximum pumping power of the 1,064-nm laser was 14.57 W, the acousto-optical (A-O) Q-switch repetition rate was 100 kHz, and the PPMgLN crystal grating period was 29.5 μm. A 1,474-nm signal light output power of 4.21 W and a 3,828 nm idler light output power of 1.547 W were obtained, corresponding to a pulse width of 9.52 ns and 9.65 ns, respectively. The overall optical–optical conversion efficiency was 39.5%. Additionally, by changing the temperature from 25°C to 150°C, a tunable signal wavelength of 1,474–1,499 nm and idler wavelength at 3,676–3,828 nm of the output laser were achieved.     

1.8 μm optical parametric oscillator based on KTiOPO4

A 1.8 ??m optical parametric oscillator pumped by a diode end-pumped acousto-optically Q-switched Nd:YAG is demonstrated. A 30-mm-long KTiOPO₄ crystal cut with an angle of ?? = 59.4°, ?? = 0° is employed as the OPO crystal. 685 mW signal laser at 1.8 ??m is obtained at the diode pump power of 13 W and the pulse repetition rate of 25 kHz. Simultaneously, 265 mW idler emission at 2.6 ??m is obtained. The corresponded diode-to-OPO conversion efficiency is 7.3%. The pulse width of the signal and idler wave are measured to be 4.5 and 2.5 ns, respectively. This gives a peak power of 6.1 and 4.2 kW, respectively.     

Acousto-optic <Emphasis Type="Italic">Q</Emphasis>-switched Tm:Ho:YbAG laser pumped at 1678 nm

Acousto-optic Q-switched lasing has been obtained for the first time in a Tm:Ho:YbAGcrystal. The laser output power is analyzed as a function of the laser pulse repetition rate. It is found that at rates above 30 kHz the laser slope efficiency reaches maximum values (~20 to 30%), comparable with the efficiency in the cw mode. The shortest laser pulse width is about 40 ns, and the average output power reaches about 80mW.     

Operation of electro-optically Q-switched Nd:LuAG laser at 1064 nm

We present the operation of a diode-pumped high-power electro-optically Q-switched 4 W Nd:LuAG laser operating at 1064 nm. At an absorbed optical power of 20 W, the laser described provides a maximum output of 3.5 W average power at a repetition rate of 50 Hz. The output varies up to a factor of 1.3% for about 1 h operation with a peak power of 280 kW, with the laser beam quality in the TEM00 mode.     

High repetition rate,Q-switched Ho:YAG laser resonantly pumped by a 20 W linearly polarized Tm: fiber laser

We describe an efficient, low-threshold, continuous-wave (CW) and Q-switched operation of a Ho:YAG laser resonantly, single-pass pumped by a 20 W linearly polarized narrow line width Tm: fiber laser at the wavelength of 1,908 nm. At room temperature for an output coupler of 30 % transmission, a maximum continuous-wave output power of 13.3 W for 18.9 W of absorbed pump power was achieved, corresponding to a slope efficiency of 73 %. In a quasi continuous-wave pumping regime, for several output couplers slope efficiencies of almost 82 % were observed. For a Q-switched operation, a Brewster-cut acousto-optic modulator was used. In a CW pumping regime, the pulse repetition frequency (PRF) was changed from 4 to 15 kHz. Under a Q-switched operation, the maximum output power of 12.25 W in relation to 15 kHz PRF was obtained; however, the maximum peak power of almost 250 kW at the PRF of 4 kHz was demonstrated. In the best case, for 4 kHz PRF, pulse energies of 2.18 mJ with a 8.8 ns FWHM pulse width (one of the shortest pulse durations observed in holmium-doped Q-switched lasers) were achieved. The laser operated at the wavelength of 2,090.23 nm with the FWHM line width of 0.95 nm. The beam quality factor of M ² was measured to be below 1.42 in both X and Y axis.     

An efficient intracavity-pumped KTP optical parametric oscillator at 1572 nm

We demonstrate an efficient and eye-safe wavelength intracavity optical parametric oscillator (OPO),based on a KTP crystal inside a Q-switched Nd:YVO4 laser end pumped by a fiber-coupled diode laser. Inthe acousto-optic Q-switched operation with the pulse repetition rate of 10 kHz, a 1572-nm eye-safe laser with the average power of 237 mW at the incident pump power of 5.64 W is obtained. Under the pulse repetition rate of 5 kHz, the signal light with pulse width of 2 ns and peak power of 18.5 kW is achieved.The conversion efficiency of the average power is 4.2% from pump diode to OPO signal output and thesignal pulse duration is about 13 times shorter than that of the depleted pump light.     

914 nm LD end-pumped 31.8 W high beam quality E-O Q-switched Nd:YVO4 laser without intracavity polarizer

We report a 914 nm LD end-pumped high power, high beam quality (M _x ² = 1.378, M _y ² = 1.287) electro-optical Q-switched Nd:YVO₄ laser with TEM₀₀-mode output. At the absorbed pump power of 67.6 W, a 31.8 W 1064 nm Q-switched laser with 43 ns pulse duration was achieved at 100 kHz repetition rate, corresponding to an optical-to-optical efficiency of 47%. The maximum pulse energy and shortest pulse width were 1.67 mJ and 18.5 ns at 10 kHz, and the calculated peak power was 90.3 kW. To the best of our knowledge, this is the highest Q-switched output power ever obtained for a Nd:YVO₄ oscillator pumped at 914 nm.     

RTP Q-switched 2 μm Tm,Ho:GdVO<Subscript>4</Subscript> Laser

In this paper, we report the performance of a diode-pumped cryogenic Tm (5 at %), Ho (0.5 at %):GdVO₄ laser with an RTP pockel cell Q-switch at different pulse repetition rate including 300 Hz, 500 Hz, 1 kHz, and 10 kHz. At the pump power of 6.96 W, the maximum output of 1.7 mJ with a pulse width of 28 ns was achieved under 300 Hz repetition rate, corresponding to a peak power of 61 kW. To the best of our knowledge, this is the first time that RTP was used as a Q-switch generator in the 2 μm Tm,Ho:GdVO₄ laser.     

A compact diode-pumped Q-switched and mode-locked Nd:GdVO4 laser based on SESAM

We report a compact passively Q-switched and Mode-locked Nd:GdVO₄ laser based on a semiconductor saturable absorber mirrors (SESAM). At a pump power of 12 W, the average output power was obtained to be 1.8 W with the repetition rate of the Q-witched envelope 80 kHz and 500 ns pulse width. The mode-locked pulses interval within the Q-switched envelope was about 1ns, corresponding to the high repetition of 1 GHz.