High-efficiency 1598.5-nm third Stokes Raman laser based on barium nitrate crystal

A high-efficiency eye-safe Raman laser was demonstrated by use of the third Stokes radiation in a Ba(NO_3)_2 crystal pumped by a 1064-nm Nd:YAG laser. The output wavelength of the Raman laser was 1598.5 nm with a full-width at half-maximum (FWHM) of 1.5 nm. With an incident pump energy of 140 mJ, a maximum of 18-mJ Raman output energy was generated at a repetition rate of 30 Hz, corresponding to an optical-to-optical conversion efficiency of 12.9%. The Raman pulse duration was shortened to 2.9 ns compared with that of the pump pulse of 19.3 ns. The eye-safe solid-state Raman laser is expected to have wide applications in range-finding, telemetry, laser radar, and other aspects.     

High-peak-power passively Q-switched 1.3 μm Nd:YAG/V~(3+):YAG laser pumped by a pulsed laser diode

We demonstrate a high-pulse-energy, short-pulse-width passively Q-switched(PQS) Nd:YAG∕V3t:YAG laser at 1.3 μm, which is end-pumped by a pulsed laser diode. During the PQS regime, a maximum total output pulse energy of 3.3 m J is obtained under an absorbed pump pulse energy of 21.9 m J. Up to 400 μJ single-pulse energy is realized with the shortest pulse width of 6.16 ns and a pulse repetition frequency of 34.1 k Hz,corresponding to a peak power of 64.9 k W. The high-energy laser pulse is operated in the dual wavelengths of 1319 and 1338 nm, which is a potential laser source for THz generation.     

A Diode-Side-Pumped Dynamic Fundamental Mode Nd：YAG Laser

A fundamental mode Nd：YAG laser is experimentally demonstrated with a stagger pumped laser module and a special resonator. The rod is pumped symmetrically by staggered bar modules. A dynamic fundamental mode is achieved with the special resonator under different pump levels. A maximal continuous wave output of 61 W （M^2 = 1.4） is achieved with a single rod. An average output of 47 W, pulse width of 54 ns, pulse energy of 4.7 mJ and peak power of 87kW are obtained under the Q-switched operation of 10 kHz.     

Kilohertz Electro-Optic Q-Switched Nd：YAG Ceramic Laser

We investigate the lasing characteristics of a laser-diode-array side-pumped electro-optic Q-switched Nd： Y3Al5O12 ceramic laser operating at 1000 Hz pulse repetition rate. Using a YAG polycrystalline rod with Nd^3＋ concentration of 1 at. % as the gain medium, pumping with 808 nm laser-diode-arrays, the Q-switched laser output at 1064 nm wavelength with 23mJ pulse energy and less than 12ns FWHM pulse width are obtained at a pumping power of about 400 W, the slope efficiency is around 15%, the output beam divergence angle is about 1.2mrad.     

A 52-mJ Ho：YAG Master Oscillator and Power Amplifier with Kilohertz Pulse Repetition Frequency

We report on a high energy, high repetition rate Ho：YAG master oscillator and power amplifier （MOPA）, res- onantly dual-end-pumped by Tm：YLF lasers at room temperature. At the pulse repetition frequency of i kHz, we demonstrate a maximum energy of 30mJ per pulse with a 28.2ns pulse width in a Ho：YAG oscillator system resonantly double-end-pumped by Tm：YLF lasers. A maximum energy of 52mJ per pulse with a 30.5ns pulse width is achieved in the Ho： YA G amplifier, corresponding to a peak power of approximately 1.7 MW. The output wavelength is at 2090.6nm and 2096.9nm, and a beam quality factor of M2-2.1 is achieved.     

A High-Pulse-Energy High-Beam-Quality Tunable Ti:Sapphire Laser Using a Prism-Dispersion Cavity

A high-pulse-energy high-beam-quality tunable Ti:sapphire laser pumped by a frequency-doubled Nd:YAG laser is demonstrated.Using a fused-silica prism as the dispersion element,a tuning range of 740-855 nm is obtained.At an incident pump energy of 774 mJ,the maximum output energy of 104 mJ at 790 nm with a pulse width of100 μs is achieved at a repetition rate of 5 Hz.To the best of our knowledge,it is the highest pulse energy at790 nm with pulse width of hundred micro-seconds for an all-solid-state laser.The linewidth of output is 0.5 nm,and the beam quality factor M~2 is 1.16.The high-pulse-energy high-beam-quality tunable Ti:sapphire laser in the range of 740-855 nm can be used to establish a more accurate and consistent absolute scale of second-order optical-nonlinear coefficients for KBe_2BO_3F_2 measured in a wider wavelength range and to assess Miller's rule q uantitatively.     

2.1μm Ho：LuAG ceramic laser intracavity pumped by a diode-pumped Tm：YAG laser

We report a compact Ho：LuAG ceramic laser intracavity pumped by a diode-pumped Tm：YAG ceramic laser. The laser oscillation is accomplished by using a common linear cavity configuration containing Tm：YAG and Ho：LuAG ceramics. The 1.0 at.% Ho：LuAG ceramic laser yields 1.15 W of maximum output simultaneously at 2094 and 2100 nm with a beam quality factor of M2-2.8.     

A Gain-Switched Fe:ZnSe Laser Pumped by a Pulsed Ho,Pr:LLF Laser

We demonstrate a gain-switched Fe:ZnSe laser pumped by a 2958 nm pulsed Ho,Pr:LLF laser. The maximum single pulse energy is 16.4uJ with a minimum pulse duration of 13.9 ns at the pulse repetition frequency of1 Hz when the Fe:ZnSe crystal is cooled to 77 K by liquid nitrogen, corresponding to a slope efficiency of 22.9%.The central wavelength and FWHM linewidth are 3957.4 nm and 23.2 nm, respectively. The output energy monotonically decreases as the crystal temperature increases in the range 77–293 K.     

Fe:ZnSe laser pumped by a 2.93-μm Cr,Er:YAG laser

We demonstrated an Fe:ZnSe laser pumped by a 2.93-μm Cr, Er:YAG laser at liquid nitrogen and room temperature in single-shot free-running operation for the first time. The xenon flash lamp pumped Cr, Er:YAG laser had a maximum single pulse energy of 1.414 J, and the threshold and slope efficiency were 141.70 J and 0.70% which were respectively reduced by 29.3% and increased by 52.2% compared with the Er:YAG laser. At liquid nitrogen temperature of 77 K, the maximum single pulse energy of the Fe:ZnSe laser was 197.6 m J, corresponding to a slope efficiency of 13.4%. The central wavelength and full width at half maximum(FWHM) linewidth were 4037.4 nm and 122.0 nm, respectively. At room temperature, the laser generated a maximum single pulse energy of 3.5 mJ at the central wavelength of 4509.6 nm with an FWHM linewidth of 171.5 nm.     

Study of passive Q-switching for flash-lamp-pumped 1.34-μm Nd:GdVO_4 laser

The static laser performance of a-growth Nd:GdVO4 crystal (a-cut, 4×4×25 (mm)) at 1.34μm pumped by flash-lamp is investigated with different transmissions of output couplers. With the output coupler transmission of T = 30%, the static output energy of 148 mJ is obtained when the pump energy is 35.2 J, and the corresponding electric-optical conversion efficiency is 0.42%. The Q-switched output of lasers with the output wavelength ranging from 1.3 to 1.6μm can be realized by using Co2 :LaMgAl11O19 (Co:LMA) as saturable absorber. A flash-lamp-pumped, passively Q-switched Nd:GdVO4 laser with Co:LMA as saturable absorber is demonstrated in plano-concave laser cavity. With the cavity length of 16.3 cm and pump energy of 19.8 J, the single-pulse output energy, pulse width, and peak power are obtained to be 4 mJ, 80 ns, and 5×104 W, respectively.     

Highly efficient single longitudinal mode-pulsed green laser

A novel design for a highly efficient 1-kHz single-frequency green laser is proposed.An efficient singlefrequency laser pulse output at 532-nm wavelength may be obtained by combining the injection seeding with intracavity frequency doubling in a compact U-shaped cavity formed by two plano dichroic mirrors in an end-pumping arrangement.The laser is capable of producing green pulses with a total energy of 6.3 mJ at a pulse repetition rate of 1 kHz.The pulse width is about 10 ns and the optical-optical efficiency from the 808-nm pump source to the 532-nm green output is around 12.7%.     

Pulse Operation of Chemical Oxygen-Iodine Laser by Pulsed Gas Discharge with the Assistance of Spark Pre-ionization

The continuous wavelength chemical oxygen-iodine laser can be turned into pulse operation mode in order to obtain high energy and high pulse power. We propose an approach to produce iodine atoms instantaneously by pulsed gas discharge with the assistance of spark pre-ionization to achieve the pulsed goal. The influence of spark pre-ionization on discharge homogeneity is discussed. Voltage-current characteristics are shown and discussed in existence of the pre-ionization capacitor and peaking capacitor. The spark pre-ionization and peaking capacitor are very helpful in obtaining a stable and homogeneous discharge. The lasing is achieved at the total pressure of 2.2-2.9 kPa and single pulse energy is up to 180 mJ, the corresponding specific output energy is 1.0 3/L.     

Experimental Study on Dual Wavelength and Dual Pulse Q-Switched Frequency Doubling on a Tunable Cr： LiSAF Laser

A flashlamp-pumped Cr：LiSAF laser system with a voltage controlled Q-switch structure in the cavity is designed. A dual-wavelength and dual-pulse tunable laser output is gained. The relation of laser output behavior with input energy is studied experimentally. The output is dual-pulsed with the energy of the 32m J/pulse producing the total output energy of 64mJ and the pulse width is about 27ns at 850nm. Then, we use one LBO crystal as the frequency doubling crystal to obtain a dual wavelength （448.1 nm and 449.15nm） and dual pulse laser. The output for one wavelength is about 10.3mJ and the line width is less than 0.02nm.     

Energy transfer in solid-state dye lasers based on methyl methacrylate co-doped with sulforhodamine B and crystal violet

Laser action in methyl methacrylate(MMA)co-doped with sulforhodamine B and crystal violet dyes was investigated.The dye mixture was incorporated into a solid polymeric matrix and was pumped by a 532-nm Nd:YAG laser.Distributed feedback dye laser(DFDL)action was induced in the dye mixture using a prism arrangement both in the donor and acceptor regions by an energy transfer mechanism.Theoretically,the characteristics of acceptor and donor DFDLs,and the dependence of their pulse widths and output powers on acceptor–donor concentrations and pump power,were studied.Experimentally,the output energy of DFDL was measured at the emission peaks of donor and acceptor dyes for different pump powers and different acceptor–donor concentrations.Tuning of the output wavelength was achieved by varying the period of the gain modulation of the laser medium.The laser wavelength showed continuous tunability from 563 nm to648 nm.     

High-power continuous-wave and high-energy Q-switched miniature Yb:Y_3Ga_5O_(12) crystal lasers

We report on the continuous-wave(CW) and passive Q-switching performance of a miniature Yb:Y_3Ga_5O_(12)crystal laser end pumped by a 935-nm diode laser. A maximum CW output power of 12.03 W is produced with an optical-to-optical efficiency of 54.4%, while the slope efficiency is 63%. In the passively Q-switched operation achieved with a Cr~(4+):YAG saturable absorber, an average output power of 2.12 W at 1025.2 nm is generated with a slope efficiency of 46% at a pulse repetition rate of 5.0 kHz. The pulse's energy, duration, and peak power are 424 μJ, 2.3 ns, and 184.3 k W, respectively.     

High-efficiency 1598.5-nm third Stokes Raman laser based on barium nitrate crystal

A high-efficiency eye-safe Raman laser was demonstrated by use of the third Stokes radiation in a Ba(NO3)2 crystal pumped by a 1064-nm Nd:YAG laser. The output wavelength of the Raman laser was 1598.5 nm with a full-width at half-maximum (FWHM) of 1.5 nm. With an incident pump energy of 140 Mj, a maximum of 18-Mj Raman output energy was generated at a repetition rate of 30 Hz, corresponding to an optical-to-optical conversion efficiency of 12.9%. The Raman pulse duration was shortened to 2.9 ns compared with that of the pump pulse of 19.3 ns. The eye-safe solid-state Raman laser is expected to have wide applications in range-finding, telemetry, laser radar, and other aspects.     

Laser-diode-pumped zigzag slab Nd:YAG master oscillator power amplifier

A high-repetition rate master oscillator power amplifier pumped with laser diodes (LDs) is reported. An injection seeding single-frequency electro-optical Q-switched Nd:YAG laser is used as an oscillator, and a conductively cooled Nd:YAG zigzag slab with a bounce-pumped architecture is utilized as a power amplifier. Pulse energies of over 800 mJ at 1 064 nm and 400 mJ at 532 nm, corresponding to average powers of 200 and 100 W, respectively, are achieved with a 12.6-ns pulse width at 250 Hz. Output frequency fluctuations and single-frequency operation are further monitored. Experimental results reveal that the proposed system, which features a single-pass amplified configuration, is a promising design for space-based applications.     

LD-pumped passively Q-switched red laser at 660 nm

A laser diode (LD) pumped Nd:YAG red pulse laser at 660 mn was presented by V:YAG passively Q-switching and LBO intracavity frequency doubling. With 1.6-W incident pump power, average output power of 46-mW, pulse duration (FWHM) of 23.3 ns, pulse repetition rate of 21.6 kHz, peak power of 91.4 W, and single pulse energy of 2.13 μJ were obtained. The beam quality factor M2 was less than 1.2. The fluctuations of pulse energy and repetition rate were less than 3% in 4 hours. The pulsed laser at 660 nm is expected to be used as the pump source of Cr3+:doped crystal to obtain the gain-switched tunable laser.     

PUMP-TUNING KTP OPTICAL PARAMETRIC OSCILLATOR WITH CONTINUOUS OUTPUT WAVELENGTH PUMPED BY A PULSED TUNABLE Ti:SAPPHIRE LASER

We report on the implementation of a KTP optical parametric oscillator pumped by a pulsed tunable Ti:sapphire laser. Two major improvements were achieved, including the connection of the signal and idler tuning ranges and the high-output conversion efficiency through the signal and idler tuning ranges. Both in the signal and idler, the continuous output wavelength from 1.261 to 2.532μm was obtained by varying the pump wavelength from 0.7 to 0.98μm. The maximum output pulse energy was 27.2mJ and the maximum conversion efficiency was 35.7% at 1.311μm (signal).     

A Q-Swicthed All-Solid-State Single-Longitudinal-Mode Laser with Adjustable Pulse-Width and High Repetition Rate

A single-longitudinal-mode （SLM） laser-diode pumped Nd： YAG laser with adjustable pulse width is developed by using the techniques of pre-lasing and changing polarization of birefingent crystal The Q-switching voltage is triggered by the peak of the pre-lasing pulse to achieve the higher stability of output pulse energy. The output energy of more than I mJ is obtained with output energy stability of 3% （rms） at lOO Hz. The pulsewidth can be adjusted from 30ns to 300ns by changing the Q-switching voltage. The probability of putting out single-longitudinal-mode pulses is almost 100%. The laser can be run over four hours continually without mode hopping.