Vertical Bridgman growth and optical properties of CdSiP2 crystals

Abstract

Single crystals of CdSiP₂ (CSP) with the dimension of 8 mm in diameter and 40 mm in length were successfully grown using vertical Bridgman method. Optical observations showed the presence of macro-defects including flaws and inclusions in the as-grown crystals. The macro-defects can be restrained through controlling the process of polycrystalline synthesis and growth parameters. For the crystals with improved qualities, the high-resolution X-ray diffraction measurement on the (004)-faced plate indicates that the full-width at half-maximum (FWHM) of the rocking curve is 34′′. The phase-matching curves calculated from refractive indices indicate that, for 1.064 μm pumping, the CSP crystal will produce a noncritically phase-matched output at 6.2 μm through a type-I parametric process, and a noncritically phase-matched output at 5.0 μm through a type-II parametric process. For 1.55 μm and 2.00 μm pumping, the crystal yields continuous tunability from 2 to 6.5 μm through a type-I parametric process. The absorption coefficients for e-polarized light at 1.064 μm, 1.55 μm and 2.0 μm of the as-grown CSP crystal are 0.53 cm⁻¹, 0.39 cm⁻¹, and 0.25 cm⁻¹, respectively.