Precise deuterium content measurement of K(HxD1−x)2PO4 crystals based on deep-UV generation

Abstract

Large-diameter K(H_xD_1−x)₂PO₄ (DKDP) crystals have been widely applied for optical parametric chirped pulse amplification and broadband UV generation in superintense ultrafast lasers and inertial confinement fusion facilities. Herein, we systematically investigated the noncritical phase-matching wavelength properties of KDP-family crystals at room temperature and demonstrated a precise characterization method for the deuterium contents of large-diameter DKDP crystals based on the ∼245 and ∼215 nm deep-UV sum-frequency generation (SFG). This SFG measurement method overcomes the low accuracy disadvantage of the Raman spectroscopy, especially for the DKDP crystals with deuterium contents of >90%. Full-range (0–100%) measurement with a precision of ∼0.148% cm was achieved, which is an enhancement of more than one order of magnitude over conventional spectroscopic schemes. This work not only has the potential to be a standard method for the deuterium content characterization of DKDP crystals, but also paves the way for energy improvement and applications of tunable deep-UV radiation by fully utilizing large-diameter characteristics of KDP-family crystals.