Effect of Cd²⁺ Doping on Laser Damage Threshold and Optical Performance of KDP Crystals

Abstract Cd 2+ ‐doped potassium dihydrogen phosphate single crystals are prepared by “point seed” method. A significant disparity is identified in Cd concentrations between pyramidal and prismatic samples, with prismatic samples exhibiting higher levels. The ultraviolet–visible (UV–vis) spectra indicate that KDP crystals doped with trace Cd 2+ exhibit increased transmittance, while those with excessive Cd 2+ show reduced transmittance in the UV region. Additionally, excessive Cd 2+ causes light absorption in the band ≈220 nm. Structural analysis is conducted utilizing infrared spectroscopy (IR). The results indicate that Cd 2+ doping distorts the chemical bonding in KDP crystals and reduces their structural stability. A detailed analysis of the photoluminescence (PL) spectro copy results shows that Cd 2+ in KDP crystals is related to increased defect concentration. The laser‐induced damage threshold (LIDT) results demonstrate that the LIDT of crystals decreases with increasing Cd 2+ doping concentration. The Cd0‐Py sample demonstrates the highest LIDT value of 16.75 J cm −2 under the R‐on‐1 condition. The value of Cd1000‐Py sample decreases to 7.46 J cm −2 in the same mode, primarily attributable to the comparatively elevated concentration of micro defects. Differential incorporation of Cd 2+ into pyramidal versus prismatic sectors is proposed, as substitutional and interstitial defects, accounts for the decrease of laser‐induced damage performance of KDP crystal based on the findings and prior reports.