A₂SnS₅: A Structural Incommensurate Modulation Exhibiting Strong Second‐Harmonic Generation and a High Laser‐Induced Damage Threshold (A=Ba, Sr)

Abstract

Structural modulations have been recently found to cause some unusual physical properties, such as superconductivity or charge density waves; however, thus‐induced nonlinear optical properties are rare. We report herein two unprecedented incommensurately modulated nonlinear optical sulfides exhibiting phase matching behavior, A2SnS5 (A=Ba, Sr), with the (3+1)D superspace groups P21212(00γ)00s or P21(α0γ)0, featuring different modulations of the [Sn2S7]∞ belts. Remarkably, Ba2SnS5 exhibits an excellent second harmonic generation (SHG) of 1.1 times that of the benchmark compound AgGaS2 at 1570 nm and a very large laser‐induced damage threshold (LIDT) of 8×AgGaS2. Theoretical studies revealed that the structural modulations increase the distortions of the Sn/S building units by about 44 or 25 % in A2SnS5 (A=Ba, Sr), respectively, and enhance significantly the SHG compared with α‐Ba2SnSe5 without modulation. Besides, despite the smaller Eg, the A2SnS5 samples exhibit higher LIDTs owing to their smaller thermal expansion anisotropies (Ba2SnS5 (1.51)<Sr2SnS5 (2.08)<AgGaS2 (2.97)).

Structural Chemistry and Excellent Nonlinear Optical Properties of a Series of Ternary Selenides GaxIn2–xSe3

“…They are caused by delamination, melting, erosion, pitting, discoloration, and fracture. Among them, the thermal expansion anisotropy (TEA) is one of the most important immanent factors that influences the LIDTs. , NLO crystals possessing smaller TEAs can sustain greater thermal shock produced by a laser beam, thus producing higher LIDTs. The temperature-dependent lattice parameters of 3 , 4 , and AGS were measured from 120 to 300 K with a step of 30 K. The TEAs of 3 , 4 , and AGS are 1.23, 2.04, and 2.97, respectively (Table S7), and the sequence is consistent with their LIDTs, which also indicates TEA is primarily affecting the LIDTs for 3 and 4 .…”

A Rare Earth Chalcogenide Nonlinear Optical Crystal KLaGeS4: Achieving Good Balance among Band Gap, Second Harmonic Generation Effect, and Birefringence

“…Midinfrared nonlinear optical (NLO) crystals are the core components of mid-infrared laser systems, which have made great contributions to the advancement of many advanced technologies, such as laser lithography, laser communication, environmental detection, and photonics. − Good NLO materials generally require high comprehensive performance, including a substantial band gap, pronounced second harmonic generation (SHG) effects, and notable birefringence. − However, these factors are commonly negatively correlated, making it a great challenge to develop outstanding NLO crystals. − So far, only limited NLO crystals are commercially available, which are dominated by ABC 2 -type chalcopyrite-like semiconductors, such as AgGaS 2 (AGS), AgGaSe 2 , and ZnGeP 2 (ZGP) . Nevertheless, the inherent shortcomings restrict their large-scale and widespread applications.…”

A Lead Mixed Halide with Three Different Coordinated Anions and Strong Second‐Harmonic Generation Response

“…Nonlinear optical (NLO) crystals can effectively broaden the wavelength range of coherent light through frequency conversion like second-harmonic generation (SHG), leading to their fascinating applications in all-solid-laser, optical parameter oscillators (OPOs) and advanced scientific instruments. [1][2][3][4][5][6][7][8] With decades of efforts, some useful NLO crystals, including LiB 3 O 5 (LBO), β-BaB 2 O 4 (BBO), KBe 2 BO 3 F 2 (KBBF), KH 2 PO 4 (KDP), KTiOPO 4 (KTP), AgGaS 2 and ZnGeP 2 , have been invented and well commercialized. LBO is the famous NLO crystal with a short transmittance cutoff edge of 158 nm.…”