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.

A 1kHz Fe:ZnSe Laser Gain-Switched by a ZnGeP2 Optical Parametric Oscillator at 77 K

We demonstrate a Fe:ZnSe laser gain-switched by a 2.9 m ZnGeP2 optical parametric oscillator under pulse repetition frequency of 1 kHz at liquid nitrogen temperature of 77 K. The maximum output power is 63 m W with pulse duration of 34.4 ns. The wavelength covers 3686.6–4088.6 nm and centers at 3897.7 nm. The output power decreases with increasing the temperature of the crystal in 77–222 K.

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.

Widely Tunable Middle Infrared Optical Parametric Oscillator Pumped by the Q-Switched Ho：GdVO_4 Laser

We demonstrate a middle infrared ZnGeP_2 optical parametric oscillator pumped by the Q-switched Ho：GdVO_4 laser. When the incident Ho pump power is 4.12 W, the maximum average output power of the ZGP-OPO laser is 2.05 W, corresponding to a slope efficiency of 74.6%. The ZGP-OPO laser produces 4.2 ns mid-infrared pulses at a pulse repetition rate of 5 kHz. In addition, we obtain 0.8 um of tunable range for the signal wave and 2.1 um of tunable range for the idler wave.

High-Power Continuous-Wave and Acousto-Optical Q-Switched Ho:(Sc_(0.5)Y_(0.5))_2SiO_5 Laser Pumped by Laser Diode

We experimentally investigate the continuous-wave(cw)and acousto-optical(AO)Q-switched performance of a diode-pumped Ho:(Sc_(0.5)Y_(0.5))_2SiO_5(Ho:SYSO)laser.A fiber-coupled laser diode at 1.91m is employed as the pump source.The cw Ho:SYSO laser produces 13.0 W output power at 2097.9 nm and 56.0%slope efficiency with respect to the absorbed pump power.In the AO Q-switched regime,at a pulse repetition frequency of 5 kHz,the Ho:SYSO laser yields 2.1 mJ pulse energy and 21 ns pulse width,resulting in a calculated peak power of 100 k W.In addition,at the maximum output level,the beam quality factor of the Q-switched Ho:SYSO laser is measured to be about 1.6.

Mid-IR Laser Generating Ultrasound in a Polyetheretherketone Polymer

We demonstrate laser ultrasonic generation in polyetheretherketone(PEEK). A middle infrared ZnGeP2 optical parametric oscillator(ZGP-OPO) pumped by a Q-switched Ho:YAG laser is employed as the ultrasonic excitation source. The ZGP-OPO has a spectral range of 3.2–3.4 μm. At an output wavelength of 3.4 μm, the maximum average output power of ZGP-OPO is 3.05 W with a pulse width of 24.3 ns, corresponding to a peak power of approximately 127.5 kW. The ultrasound is generated by the laser converted from 3.2 to 3.4 μm in the PEEK composite. The maximum ultrasonic signal amplitude in PEEK is 33 mV under the condition of thermoelastic excitation at 3.4 μm. Ablation occurs in the CPRF sample when the energy fluence is over 122.45 m J/cm^2. PEEK has a stronger absorption at 3.4 μm and laser-ultrasound generation is influenced by the wavelength of the laser.

Microstructural evolution and mechanical properties of h-BN composite ceramics with Y2O3-AlN addition by liquid-phase sintering

Hexagonal boron nitride(h-BN)composite ceramics were prepared by hot pressing with the addition of Y2O3 and AlN.The effects of different Y2O3–AlN contents on microstructural evolution,mechanical properties and thermal diffusion coefficients of h-BN composite ceramics were investigated.The results indicate that Y2O3–AlN forms a liquid phase during the sintering process achieving a good wettability with h-BN grains.In pure h-BN ceramic and h-BN composite ceramic with 40 wt%Y2O3–AlN,the h-BN grains grow well when controlled through solid-phase and liquid-phase diffusion,respectively.With the increase in Y2O3–AlN content,mechanical properties and thermal diffusion coefficients of h-BN composite ceramics first decrease and then increase,and the properties of h-BN composite ceramic with 10 wt%Y2O3–AlN are the inflection points.Such properties are highly related to the phase compositions,porosity and microstructure.