Homogeneity of large rapidly grown ADP crystals

Abstract

DKDP crystal is a type of well-known excellent nonlinear optical material that can be used as 2ω, 3ω, and even 4ω harmonic converters. Compared to DKDP crystal, ADP has a larger nonlinear optical coefficient and higher laser damage threshold, so a larger energy and higher conversion efficiency can be expected from ADP crystals. In this paper, a high-quality ADP crystal (118×137×160 mm) was grown through point-seed rapid growth method within one month. The corresponding optical properties and homogeneity for noncritical phase-matching fourth harmonic generation were investigated. For the ADP sample with cross-section of 110×110 mm, the obtained homogeneity noncritical phase-matching temperature is 0.13°C, which is superior to a DKDP crystal with the same growth parameters. Moreover, UV transmittance property of various thicknesses for ADP crystals was also explored. The transmittance at 263 nm is 88% and decreased 0.36% per millimeter. This result is much lower than the 0.63% for the DKDP crystal in the same thickness range. These results indicate ADP crystals are very promising candidates for noncritical phase-matching fourth harmonic generation.