Giant Non-resonant Infrared Second Order Nonlinearity in $\gamma$-NaAsSe${}_2$

Abstract

Infrared laser systems are vital for applications in spectroscopy, communications, and biomedical devices, where infrared nonlinear optical (NLO) crystals are required for broadband frequency down-conversion. Such crystals need to have high non-resonant NLO coefficients, a large bandgap, low absorption coefficient, phase-matchability among other competing demands, e.g., a larger bandgap leads to smaller NLO coefficients. Here, we report the successful growth of single crystals of $\gamma$-NaAsSe${}_2$ that exhibit a giant second harmonic generation (SHG) susceptibility of d${}_{11}$=590 pm V${}^{-1}$ at 2$\mu$m wavelength; this is ~ eighteen times larger than that of commercial AgGaSe${}_2$ while retaining a similar bandgap of ~1.87eV, making it an outstanding candidate for quasi-phase-matched devices utilizing d${}_{11}$. In addition, $\gamma$-NaAsSe${}_2$ is both Type I and Type II phase-matchable, and has a transparency range up to 16$\mu$m wavelength. Thus $\gamma$-NaAsSe2 is a promising bulk NLO crystal for infrared laser applications.

Main text: 21 pages, 4 figures

References in corpus (1)

• Two-dimensional Materials with Giant Optical Nonlinearities Near the Theoretical Upper Limit