Li₂ZnGeS₄: a promising diamond-like infrared nonlinear optical material with high laser damage threshold and outstanding second-harmonic generation response

Abstract

A promising IR nonlinear optical material Li2ZnGeS4 with a diamond-like configuration and high optical performance is reported.

α-Li2ZnGeS4: A Wide-Bandgap Diamond-like Semiconductor with Excellent Balance between Laser-Induced Damage Threshold and Second Harmonic Generation Response

“…In early 2019, Pan and co-workers reported another phase of Li 2 ZnGeS 4 , namely β-Li 2 ZnGeS 4 (Pn), synthesized using a much higher temperature. 33 The lattice parameters in Pan's report are nearly identical to those determined by Kanno et al, with the exception that Kanno's team indicated that the structure was orthorhombic, while Pan's group found the compound to be monoclinic with a beta angle near 90°. We ascertained that the Pna2 1 structure, reported here, should be the low-temperature phase.…”

“…This interpretation of the DTA thermogram is speculative, but supported by the synthetic procedures used to obtain each phase. The title compound, α-Li 2 ZnGeS 4 , was prepared with a high-temperature hold at 680−700 °C, below the observed thermal events, while β-Li 2 ZnGeS 4 was prepared by Pan and coworkers at 900 °C, 33 above the recorded transition temperatures.…”

Phase Matching, Strong Frequency Doubling, and Outstanding Laser-Induced Damage Threshold in the Biaxial, Quaternary Diamond-like Semiconductor Li4CdSn2S7

“…Chalcogenides are a treasure mine of excellent IR-NLO materials because of their superior optical transparency in the IR and their large polarizability that can lead to significant second harmonic generation (SHG) responses. Thus, many researchers are searching for new IR-NLO chalcogenides among a variety of subclasses. − Our strategy has been to focus on the family of quaternary DLSs − because they are inherently noncentrosymmetric (NCS), the first criterion for SHG.…”

“…Therefore, in order to critically evaluate the balance between LIDT and χ (2) , experimental measurements must be carried out on quality materials. Many groups have begun to report LIDT along with χ (2) and some promising materials have been identified. − Among these, some lithium-containing DLSs of the formulae I 2 –II–IV–VI 4 and I 4 –II–IV 2 –VI 7 demonstrate a good balance of a large χ (2) and a high LIDT, for example, Li 2 ZnSiS 4 , Li 2 HgSiS 4 , α-Li 2 ZnGeS 4 , β-Li 2 ZnGeS 4 , Li 2 CdGeS 4 , Li 2 MnGeS 4 , and Li 4 HgGe 2 S 7 …”

Stepwise Li Substitution Induced Structure Evolution and Improved Nonlinear Optical Performance for Diamond-like Sulfides

“…Most of commercial infrared (IR) NLO materials are crystallized with diamond-like (DL) structures. , Though they possess several advantages, their applications are still restricted with several drawbacks. For instance, the main commercialized AgGaS 2 (AGS), AgGaSe 2 (AGSe), and ZnGeP 2 (ZGP) display large second-harmonic generation (SHG) intensities while suffering from low LIDT or two-photon absorption (TPA). , In the pursuit of high performance IR NLO crystals, DL structures are attractive because of their inherently noncentrosymmetric (NCS) feature. , All of the cations in DL materials naturally adopt asymmetric tetrahedral coordination geometry, and all tetrahedral structural units tend to be arranged in the same crystallographic direction, thus resulting in NCS structures with high polarity, which is a prerequisite for NLO materials. , Based on this point, some promising materials have been identified, including Li 0.60 Ag 0.40 GaS 2 , Li 2 ZnSiS 4 , α-Li 2 ZnGeS 4 , β-Li 2 ZnGeS 4 , and Li 4 CdSn 2 S 7 …”