Extremely high laser damage threshold of organic nonlinear optical crystals L-arginine phosphate and its deuterium compound

Abstract

Organic L-arginine phosphate (LAP) and deuterated LAP (DLAP) are new nonlinear optical materials for higher harmonic generation of high power lasers. We measured the bulk laser damage threshold of these crystals. Single-mode Nd3+:YLiF4 lasers (1.053 µm:ω) with 1- and 25-ns pulses and those second harmonics (0.526 µm:2ω) were used. KH2PO4 crystal and fused silica were also tested as references. Both LAP and DLAP showed extremely high damage threshold compared with KH2PO4 and fused silica in every case. Comparing LAP and DLAP, DLAP showed especially higher threshold than LAP in the case of ω with a 25-ns pulse. This may be due to the fact that absorption coefficient of LAP at ω is larger than that of DLAP. We do not understand why organic LAP and DLAP can have such a high damage threshold compared with inorganic KH2PO4 or fused silica. Mechanical properties of these crystals may have a relationship to the damage mechanism.