A Ferroelectric Nonlinear Optical Crystal for Deep‐UV Quasi‐Phase‐Matching

Abstract

Phase matching is indispensable for high efficiency of second‐order nonlinear optical (NLO) crystals. Thousands of these crystals rely on birefringence phase matching, whereas only a few of them are quasi‐phase matching without the restriction of birefringence. Herein, using oriented seeds inch‐sized LiNH4SO4 (LAS) single crystals are successfully grown. LAS is NLO‐active with a very short deep‐UV absorption edge of 171 nm and high laser damage threshold up to 1.47 GW cm−2 at 1064 nm, 10 ns, but its birefringence is merely 0.0078@532 nm, which is too small to realize birefringence phase matching in deep‐UV region. Fortunately, P−E hysteresis loop, variable‐temperature NLO tests, and ferroelectric domain observations confirm that LAS is ferroelectric. Furthermore, LAS exhibits small refractive index dispersion resulting in a relatively long periodic length of 1.4 µm and its single domain structure can be easily obtained by electrical poling. These attributes make LAS a scarce NLO candidate for deep‐UV quasi‐phase matching. This work highlights the longly overlooked potential of sulfates and provides new opportunities for deep‐UV NLO materials.

Hg4(Te2O5)(SO4): A Giant Birefringent Sulfate Crystal Triggered by a Highly Selective Cation

“…1,2 The long overlooked SO 4 tetrahedron has been found to be a good type of functional unit used in nonlinear optical materials. 3,4 However, the highly symmetrical SO 4 groups often result in a low birefringence of sulfates, 5 such as LiNH 4 SO 4 (0.0078@532 nm) 6 and LiKSO 4 (0.00025@546 nm). 7 Such a small birefringence prevents many sulfates from achieving phase matching by a direct second-harmonic generation process, hindering the application of sulfate crystals.…”

“…Sulfate crystals are receiving increasing attention in the research of optoelectronic functional materials due to their tetrahedral building unit, wide optical band gap, short UV cutoff edge, and easy crystal growth. , The long overlooked SO 4 tetrahedron has been found to be a good type of functional unit used in nonlinear optical materials. , However, the highly symmetrical SO 4 groups often result in a low birefringence of sulfates, such as LiNH 4 SO 4 (0.0078@532 nm) and LiKSO 4 (0.00025@546 nm) . Such a small birefringence prevents many sulfates from achieving phase matching by a direct second-harmonic generation process, hindering the application of sulfate crystals. , …”

Crystal Structure and Optical Characteristics of K2Nd2O(BO3)2

“…Solid state lasers have great application values in the fields of scientific research, industrial processing, communication, medical treatment, astronomy, and so on. [1][2][3][4] Laser crystal is one of the most commonly used gain media, in which various rare earth (RE) ions or transition metal ions are employed as activated ions. The Nd 3 + ion is one of the most widely used activated ions on account of its multiple energy level transitions.…”

Electrically Induced Crystal Field Distortion in a Ferroelectric Perovskite Revealed by Electron Paramagnetic Resonance

“…Considering the structural tunability and potential to accommodate various functions, the ABX 3 organic–inorganic hybrid ferroelectric perovskite is chosen for our study of the SEC effect and its optimization. − Various metal ions can fit into the B-site without destroying the original structure, making it easy for the magnetoelectric property to be tailored. The A-site organic cations in ABX 3 molecular ferroelectrics are mostly low-symmetric ammonium cations, which can be disordered in the high temperature and ordered in the low temperature, leading to structural phase transition accompanied with spontaneous polarization or ferroelectricity induced by cooling.…”

“…In this article, the Mn-doped organic–inorganic hybrid perovskite, ferroelectric [(CH 3 ) 3 NCH 2 Cl]­(Mn 0.001 Cd 0.999 )­Cl 3 (TMCM-Mn) with a large piezoelectric effect ( d 33 = 220 pC/N), is studied. Angle-dependent CW-EPR experiments are performed to determine the ZFS tensor of Mn­(II).…”