Edge-pumped passively Q-switched thin Nd:YAG slab lasers

We report a high-power thin Nd：YAG slab laser with slab dimension of 1 × 10 ×60 （mm） partially edgepumped by diode laser arrays. Passive Q-switching is achieved with a Cr^4＋ ：YAG microchip adopted as the saturable absorber mirror. The pulse duration is around 10 ns while the pulse repetition rate is higher than 10 kHz. The average output power of 70 W is obtained with a slope efficiency of 36%. The diffraction limited beam quality in the thickness direction is obtained by controlling the pump beam diameter inside the slab. The laser head is very compact with size of only 60 × 74×150 （mm）.

Q-switched mode-locked diode-pumped Nd:YVO_4 laser with a saturable Bragg reflector

We demonstrated a diode-pumped passively Q-switched mode-locked Nd:YVO4 laser by using a relaxed saturable Bragg reflector (SBR). Stable mode-locked pulse train with the repetition rate of -230 MHz was achieved and the pulse train was modulated by the Q-switched envelope with the repetition rate of -150 kHz. The maximum output of 4 W was obtained under the pump power of 13.5 W. The optical-to-optical efficiency was 30%. We also discussed the transition of each process having emerged.

Performance evaluation of ZnGeP_2 optical parametric oscillator pumped by a Q-switched Tm,Ho:GdVO_4 laser

A doubly resonant ZnGeP2 （ZGP） optical parametric oscillator （OPO） pumped by a novel Tm,Ho：GdVO4 laser was demonstrated. Cryogenic Tin（5 at.-%）, Ho（0.5 at.-%）：GdVO4 laser with high pulse repetition frequency （PRF） of 10 kHz at 2.05 μm was employed as pumping source of ZGP OPO. The 15-mm-long ZGP crystal, 55° cut for I-type phase-matching with low absorption coefficient less than 0.05 cm^-1 at 2 μm, was placed in a piano-piano cavity with resonator length of 30 mm. The ZGP OPO generated a total combined output power of 1.2 W at 3.75 and 4.52 μm under pumping power of 5.3 W, corresponding to slope efficiency of 40% from incident 2μm laser power to midinfrared （Mid-IR） output. A widely tunable range from 3.0 to 6.5 μm was achieved by changing the crystal angle only 3.5°.

All solid-state passively Q-switched frequency-doubled intra-cavity Nd:GdVO_4/KTP laser

In this paper, laser frequency-double and passive Q-switching are studied. The optimum coupling at endpump and optimum design of resonator are also investigated. The maximum output power of TEMoo is 1.68 W at 1.06-μm wavelength. Optic-optic conversion efficiency is 48.6%, and the slope efficiency is 56.3%. The maximum output of greeh light is 0.235 W. The smallest pulse-width of green light is 27.42 ns, optic-optic conversion efficiency of green light is 7%, and beam quality factor M^2 〈 1.2. Thermal lens effect is discussed.

Diode-side-pumped AO Q-switched Tm,Ho:LuLF laser

A diode-side-pumped Tm,Ho：LuLiF laser at 2μm wavelength obtained in a ring resonator and its amplification experiment are reported. At the maximum pump energy of 4.7 J available for the oscillator, the output energy per pulse for the oscillator decreases from 904 to 483 mJ in free running mode, and decreases from 106 to 68 mJ in Q-switched mode, with an increase of pump pulse repetition rate from 1 to 5 Hz. When considering the amplifier, 99-mJ Q-switched output energy is achieved at 5-Hz repetition rate.

Diode-pumped passively Q-switched Nd:YVO_4 laser with GaAs saturable absorber

The intracavity photon density is assumed to be of Gaussian spatial distributions and its longitudinal variation is also considered in the rate equations for a laser diode (LD) end-pumped passively Q-switched Nd:YVO4 laser with GaAs saturable absorber. These space-dependent rate equations are solved numerically. The dependences of pulse width, pulse repetition rate, single-pulse energy, and peak power on incident pump power are obtained. In the experiment, the LD end-pumped passively Q-switched Nd:YVO4 laser with GaAs saturable absorber is realized and the experimental results are consistent with the numerical solutions.

Intracavity optical parametric oscillator at 1.57-μm wavelength pumped by passive Q-switched Nd:GdVO_4 laser

A high-repetition-rate eye-safe optical parametric oscillator （OPO）, using a non-critically phase-matched KTP crystal intracavity pumped by a passively Q-switched Nd：GdVO4/Cr^4＋ ：YAG laser, is experimentally demonstrated. The conversion efficiency for the average power is 7% from pump diode input to OPO signal output and the slope efficiency is up to 10.3%. With an incident pump power of 7,3 W, the compact intracavity OPO （IOPO） cavity, operating at 15 kHz, produces an average power of 0.57 W at 1570 nm with a pulse width as short as 6 ns. The peak power at 1570 nm is higher than 6.3 kW.

Experimental investigation on Q-switching and Q-switched mode-locking operation in gold nanorods-based erbium-doped fiber laser

We report on the generation of Q-switched and Q-switched mode-locked （QML） pulses in an erbium-doped fiber ring laser by using a polyvinyl alcohol （PVA） -based gold nanorod （GNR） saturable absorber （SA）. The PVA- based GNR SA has a modulation depth of -4.8% and a non-saturable loss of -26.9% at 1.5 μm. A Q-switched pulse train with a repetition rate varying from 18.70 to 39.85 kHz and a QML pulse train with an envelope repetition rate tuning from 20.31 to 31.50 kHz are obtained. Moreover, the lasing wavelengths of the Q-switched pulses can be flexibly tuned by introducing a narrow bandwidth, tunable filter into the laser cavity. The results demonstrate that the GNRs exhibit good optical performance and can find a wide range of applications in the field of laser technology.

Experimental study of continuous-wave and Q-switched laser performances of Ho:YVO4crystal

In this letter, we report a Ho：YVO4 laser pumped by a 1.94-μm laser in both continuous-wave （CW） and Q-switched modes. The output performance of the Ho：YVO4 laser is compared with different output coupler transmissions. By use of the output coupler transmissions of T=30%, we obtain the maximum CW output power of 3.9 W at 2052 nm, with beam quality factor of M2=1.09 for the absorbed pump power of 12.5 W. For the Q-switched mode, we achieve maximum output energy per pulse of 0.38 mJ and the minimum pulse width of 25 ns, corresponding to the peak power of 15.2 kW.

Stable single-mode operation of injection-seeded Q-switched Nd:YAG laser by sine voltage modulation

Based on the modified ramp and fire technique, a novel injection seeding approach with real-time resonance tracking is successfully demonstrated in a single-frequency Nd：YAG pulsed laser. Appling a high-frequency sinusoidal modulation voltage to one piezo actuator and an adjustable DC voltage to another piezo actuator for active feedbackm single-mode laser output with high-frequency stability is obtained, and the effect of the piezo hysteresis on the frequency stability can be eliminated for a laser diode pumped @switched Nd：YAG laser at a repetition rate of 400 Hz.

Pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser

A pre-pumped passively Q-switched Nd:YAG/Cr: YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum (FWHM) is 734 ps, and the pulse energy is 5.5 μJ with a fundamental spatial mode. In this system, the pre-pumped microchip laser of Nd: YAG/Cr: YAG wafer which is bonded through the thermal-bonding technique has achieved a time jitter value of 12 μs and a Q-switched amplitude instability of 1.26% (1δ) through the pre-pumped modulation technique.

Watt-level high-power passively Q-switched laser based on a black phosphorus solution saturable absorber

A novel black phosphorus （BP） solution saturable absorber （SA） is fabricated by the liquid-phase-exfoliated method and successfully used for passively Q-switched （QS） Nd：YVO4 laser. Compared with a traditional solid SA, a BP solution SA possesses more excellent optical transparency and higher damage resistance. The shortest pulse duration and highest average output power are measured to be 119 ns and 1.23 W, respectively. To the best of our knowledge, both of them are the best results among QS solid-state lasers with BP-based absorbers so far. The repetition rate is in the range of 533.2 to 722 kHz. The results indicate the potential application of the BP solution SA into high-Dower solid-state pulse lasers.

Pulse width reduction in diode-pumped,doubly Q-switched Nd:GdVO_4/KTP green laser

Using both acoustic-optic (AO) Q-switeh and GaAs saturable absorber, a diode-pumped doubly Q-switehed Nd:GdVO4/KTP green laser is realized. This laser can generate a shorter and more symmetric pulse in comparison with purely AO and passively Q-switched lasers. In the meantime, the rate equations describing the operation of a diode-pumped, AO and GaAs doubly Q-switched Nd:GdVO4/KTP green laser are introduced. These equations are solved numerically and the dependence of pulse width on incident pump power is obtained. The numerical solutions are in agreement with the experimental results.

Acousto-optic Q-switched cladding-pumped ytterbium-doped fiber laser

A diode-pumped, acousto-optic Q-switched fiber laser is presented based on multimode ytterbium-doped fiber. The fiber with core diameter of 30 μm is used to increase the laser gain volume and the pulse energy efficiently. The average power in excess of 9 W is obtained at the repetition rate of 20 kHz with 66% slope efficiency. The pulse width is 198 ns with no evident amplified spontaneous emission between pulses, thus the pulse energy and peak power are 465 μJ and 2.36 kW, respectively.

An LD-pumped dual-wavelength actively Q-switched Nd:Sc_(0.2)Y_(0.8)SiO_5 laser

We demonstrate a laser-diode （LD） pumped actively Q-switched laser with Nd：Sc0.2Y0.5SiO5 （Nd：SYSO） crystal for the first time. A stable actively Q-switched laser is obtained at dual wavelengths of 1 075.2 nm and 1 078.2 nm. The maximum average output power of 720 mW is obtained at the repetition rate of 15 kHz under the pump power of 8.7 W. The minimum pulse width of 58 ns is obtained at the repetition rate of 5 kHz under the pump power of 8.7 W, corresponding to the peak power of 1.9 kW and the pulse energy of 112 μJ.

Threshold characteristic of intracavity optical parametric oscillator pumped by all-solid-state Q-switched laser

We derive the threshold pump intensity for a singly resonant intracavity optical parametric oscillator （IOPO） based on a temporal coupled field model. Particular attention is paid to the dependence of the intracavity singly resonant OPO （SRO） threshold intensity on the signal wave output coupling. Meanwhile, a Nd：YAG laser pumped KTiOPO4 （KTP） IOPO for eye-safe laser output is studied experimentally. The experiment is performed with four signal wave output reflectivities of 60%, 70%, 80%, and 90%, respectively. The measured values are in good agreement with the theoretical results. With an output coupler reflectivity of 80%, a peak power of 70 kW at 1572 nm has been obtained at a repetition rate of 3.5 kHz. The pulse width is 4.9 ns. Such investigation is helpful to identifying suitable operational regime of low pump intensity.

Electro-optically Q-switched RF excited partial Z-folded CO_2 waveguide laser

An electro-optically Q-switched partial Z-folded RF CO2 waveguide laser with an intracavity CdTe modulator has been designed and characterized. The partial Z-fold channel is 3 x 460 mm in length. In this paper we study the laser output power as a function of gas pressure for partial Z-fold channel without Q-switched crystal inside the cavity. The maximum laser output power is about 21 W. For Q-switch operation, the peak power is 730 W and the pulse width is 150 ns.

Efficient intracavity optical parametric oscillator with diode side-pumped electro-optic Q-switched laser

An efficient intracavity single-resonant optical parametric oscillator （OPO） at 1.571-μm eye-safe range using a non-critically phase-matched KTP crystal is reported. The OPO is excited by a diode side-pumped electro-optic Q-switched Nd：YAG laser at 1.064 μm. Signal pulse of 97 mJ and 3.56 ns is obtained under the input electric energy of 2.3 J, corresponding to a slope efficiency of 4.2%, and a repetition rate range of 1-30 Hz. OCIS codes： 190.2620, 140.3480, 140.3540, 140.0140.

Diode-pumped, Cr:YAG passively Q-switched and mode-locked Nd:YVO_4/KTP green laser

The phenomena of simultaneous Q-switching and mode-locking in a diode-pumped Nd:YVO4/Cr:YAG/ KTP green laser are reported and discussed in this paper. With 5.3-W pump power, by using a nearly hemispherical cavity (the cavity length is only 97 mm), the results of modulation depth of 70% and the period of 0.6 ns are obtained, the output power and the repetitive frequency of Q-switched pulse are 90 mW and 12 kHz, respectively.

Frequency-dispersive method for improving broad-band SBS phase conjugation of Cr:LiSAF laser

After passing through four dispersive-prisms, the Q-switched Cr.LiSAF laser with broad frequency band is focused into carbon disulfide (CS2) to produce backward stimulated Brillouin scattering (SBS). Our experimental results and illustrative analysis have shown that this frequency-dispersive method can efficiently reduce the broad-band SBS intensity threshold, compress its pulsewidth, and improve the beam quality.