Search

Dual-frequency solid-state microchip lasers have advantages, such as large frequency differences, high pumping efficiency, high beam quality, and narrow laser linewidth. In addition, they are characterized by simplicity, compactness, stability, long lifetime, etc. However, the frequency difference of the dual-frequency solid-state microchip laser cannot be modulated and is only determined by its internal stress. The stress distribution inside the microchip laser is uneven and the stability of the frequency difference needs to be improved furthermore, which limits its applications. The structure of a Nd:YAG laser resonator, the mechanism of dualfrequency generation, and the output characteristics are studied. The relationship between the polarization direction of the pumping laser and the intensities of the dual-frequency components is theoretically and experimentally researched, realizing the maximum amplitude of the beat signal. Based on the photoelasticity theory, the relationship between the frequency difference and the external force is analyzed and the PID closed-loop frequency difference controlling system based on the piezoelectric transducer is proposed and realized. By applying the closed-loop control, the frequency difference of the Nd:YAG laser can be continuously modulated in the range from 24 to 30 MHz and the fluctuation is less than 450 kHz. The high-performance Nd:YAG dual-frequency solid-state microchip laser with stable and adjustable frequency difference is achieved. [ABSTRACT FROM AUTHOR]

The output window of a high-power laser system is vulnerable to damage, and this is the main limiting factor on the power scaling and structure integrity of the laser system. In endeavoring to obtain higher output powers from the laser system, the impact of the thermal and mechanical effects and the damage mechanism of the output window must be considered. In order to study these issues, a thermal model of the laser window is established based on the heat transfer and thermoelastic theories, and the expressions for the transient thermal and mechanical stress distributions of the output window are deduced in terms of the integral-transform method. Taking the infrared quartz window material as an example, the temperature and mechanical field distributions of a high-power all-solid-state 2-µm laser system window are simulated, and the laser-induced damage mechanism is deeply analyzed. The calculation results show that the laser window-induced damage is mainly caused by melting damage when the temperature exceeds the melting point of the material. The presented theoretical analysis and numerical simulation results are significant for the design and optimization of high-power laser windows. [ABSTRACT FROM AUTHOR]