A study on dual laser beam separation technology of KDP crystal

• A dual laser beam separation technology for KDP crystal was first developed.
• A non-pollution crystal surface and a separated sidewall without subsurface damage and limbic fragmentation were achieved.
• A 20 times faster separating speed than conventional method was achieved.
• A numerical simulation to analyze the mechanism of DLBS separating KDP crystal was developed.

KDP crystal is an important optic-electro material in various laser systems, at present, the greatest difficulty is the cutting of large-scale crystals. In this study, a dual laser beam separation technology (DLBS) for KDP crystal has been developed by skillfully combining femtosecond laser and continuous fiber laser for the first time. The principle of DLBS is expounded. The effects of laser separating parameters, including laser output power, scanning speed, focal position and focal length on separating accuracy and quality (flatness and surface roughness Sa of the separated sidewall) were investigated. The key parameters were determined and optimized for the separating of raw materials with the minimal flatness and the separating of the end product crystals with minimal Sa. The results show that a clean crystal surface and an average Sa of 2.6843 μm separated sidewall without any pollution, subsurface damage and limbic fragmentation could be achieved by DLBS. The separating speed of DLBS is at least 20 times faster than that of the conventional method. A numerical simulation to analyze the mechanism of DLBS separating KDP crystal was developed, which is in good agreement with the theoretical analysis and experimental results.

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