Honeycomb layered topology construction for exceptional long-wave infrared nonlinear optical crystals

Abstract

Nonlinear optical (NLO) crystals capable of efficient long-wave infrared (8-14 μm) laser output remains scarce, and the exploration of long-wave IR NLO materials with superior comprehensive optical performances is a...

Hg3Se(SeO3)(SO4): A Mixed-Valent Selenium Compound with Mid-Infrared Transmittance Obtained by In Situ Reaction

“…The UV cutoff edge is ∼282 nm, corresponding to a band gap of 3.5 eV (Figure S6). It is comparable with the previously reported sulfate−selenite mercury of Hg 2 (SeO 3 )(SO 4 ) (3.58 eV), 47 which far exceeds the previously reported Hg-based chalcogenide compounds 48 such as Ba 2 HgTe 5 (1.28 eV), 49 AgHgPS 4 (2.63 eV), 50 (Na 3 Rb)Hg 2 Ge 2 S 8 (2.76 eV), 51 KHg 4 Ga 3 S 9 (3.0 eV), 52 BaHgGeS 4 (3.04 eV), 53 and Zn 2 HgP 2 S 8 (3.37 eV). 54 Compared to the bandgap of 2.63 eV for (Hg 3 Se 2 )(Se 2 O 5 ), the band gap of Hg 3 Se(SeO 3 )(SO 4 ) is significantly improved, due to the effect of SO 4 .…”

Hg3AsS4X (X = Cl and Br): two Hg-based chalcogenides as long-wave infrared nonlinear optical crystals with superior comprehensive performances

“…1e), respectively, decreasing the interlayer spacing and creating favorable growth conditions. 9 It is worth noting that the [Hg 3 S 6 ] groups were slightly corrugated due to above electrostatic attraction of Cl − ions toward Hg 2+ , whereas all [AsS 3 ] groups were uniformly arranged along the c -axis with a structure criterion ( C ) of 1 (present in Fig. 1d and section of computation), which means that the [AsS 3 ] groups were optimally arranged, contributing to optimization of the NLO performance.…”

“…The large optical anisotropy was created by asymmetric electron polarization along the c -axis in the [Hg 3 AsS 4 ] + layer due to structural anisotropy, while Cl − /Br − contributed little to the birefringence due to the isotropic electron density distribution. 9…”

“…In fact, the difficulties involved in exploring IR NLO crystals are primarily centred around achieving a balance between second-harmonic generation (SHG) effects, laser damage thresholds (LDT), birefringence and IR transparency. 6–8 However, these NLO properties are strongly interconnected and contradictory, 9,10 which presents a huge challenge. For instance, large SHG coefficients of ZnGeP 2 crystal render it an excellent IR NLO crystal.…”

The first polyanion-substitution-driven centrosymmetric-to-noncentrosymmetric structural transformation realizing an excellent nonlinear optical supramolecule [Cd4P2][CdBr4]

“…A noncentrosymmetric (NCS) crystallographic structure is an essential prerequisite for symmetry-dependent properties, such as pyroelectric, ferroelectric, piezoelectric, and second-order nonlinear optical (NLO) materials. 1–3 After considering the structural characteristics, practical strategies have been put forth for creating NCS materials, which can commonly be classified into the following categories. Primarily, NCS crystals can be synthesized using basic structural and functional motifs, 4 including distorted polyhedrons centered by second-order Jahn–Teller effects or stereochemically active lone pair cations, asymmetrical tetrahedral units, and plane-trigonal π-orbital systems.…”