Theoretical Design and Practical Application of Non-aqueous Ultrasonic in the Surface Purifying of Large Aperture KDP Crystal for High-power Laser System

Abstract

Potassium dihydrogen phosphate (KDP) crystal is a very crucial nonlinear optical element to double the frequency of original laser in the high-power laser system, in order to obtain the laser with desired frequency and power to realize the ignition of inertial confinement fusion. The surface defects on KDP crystal including scratch, pit, and so on will greatly reduce its resistance of laser damage, which is considered the major problem to realize high power output from the high-power laser system. Ultrasonic, as the most conventional cleaning approach has been introduced and studied in the surface purifying of large aperture KDP crystal to mitigate its surface defects, which is hardly investigated due to the brittle property and expensive price of KDP. Theoretical design and practical application of ultrasonic for large aperture KDP crystal has been specifically studied in this paper, which finally achieved the efficient and defect-free purification of KDP surface.