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.     

非线性晶体应用于中长波红外固体激光器的研究进展

中波红外3～5μm波段以及长波红外8～12 μm波段的激光处于大气传输窗口,在激光成像、环境监测、激光雷达、激光医疗、化学遥感和红外对抗等领域有着非常广阔的应用前景.基于非线性光学晶体,采用光学非线性频率变换技术在实现中长波红外固体激光输出方面具有明显的技术优势.该方法激光器结构简单,且晶体本身并不参与能量交换,因而没有量子亏损,从而产热很少.同时具有单色性好、宽调谐、高功率等优点.本文针对常用以及新型非线性光学晶体,对其应用于中长波红外固体激光器的研究进展做了详细的总结.     

Beam quality improvement of the high-energy KTA-OPO based on a confocal unstable cavity with Gaussian reflectivity mirror

A high-energy 100-Hz optical parametric oscillator (OPO) based on a confocal unstable resonator with a Gaussian reflectivity mirror was demonstrated.A KTA-based OPO with a good beam quality was obtained when the magnification factor was 1.5,corresponding to the maximum signal (1.53μm) energy of 56 m J and idler (3.47μm) energy of 20 m J,respectively.The beam quality factors (M²) were measured to be M²_x=5.7,M²_y=5.9 for signal and M²     

A 1kHz Fe:ZnSe Laser Gain-Switched by a ZnGeP_2 Optical Parametric Oscillator at 77 K

We demonstrate a Fe:ZnSe laser gain-switched by a 2.9 m ZnGeP_2 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.     

1 kHz nanosecond-pulsed room temperature Fe:ZnSe laser gain-switched by a ZnGeP_2 optical parametric oscillator

We demonstrate a Fe:ZnSe laser gain-switched by a ZnGeP_2 optical parametric oscillator(OPO) under the pulse repetition frequency of 1 kHz at room temperature. The 2.9 μm signal light of the OPO is employed as the pump for the Fe:ZnSe laser. The maximum output power of the Fe:ZnSe laser is 58 mW with the pulse duration of 2.7 ns under the incident pump power of 280 mW, corresponding to a peak pulse power of 21.5 kW and an optical-to-optical efficiency of 20.7%. The spectrum of the Fe:ZnSe laser has a range of 4030.2–4593.6 nm with a dip at 4187.1–4340.4 nm due to the absorption of CO_2.