Pushing Nonlinear Optical Oxides into the Mid-Infrared Spectral Region Beyond 10 μm: Design, Synthesis, and Characterization of La₃SnGa₅O₁₄

Abstract

Mid-infrared (mid-IR) coherent light is crucial for several applications in science as well as daily life, and its development especially in powerful augmentation is constrained by the availability of nonlinear optical (NLO) materials. The development of useful mid-IR NLO materials is limited by the requirements of a wide mid-IR transparent window, high laser damaged threshold (LDT), and strong NLO effect. It is common knowledge that oxides are not suitable mid-IR NLO materials, as their IR absorption cutoff wavelengths are usually <6 μm; however, their LDTs and NLO effects can be large. Herein, we focused on langasite oxides and built structure-composition-property maps that describe the NLO properties in these materials by combining computational property prediction and experimental characterization. Accordingly, rational molecular design was performed, a new member of the langasite family, LaSnGaO (LGSn), was synthesized, and single crystals were grown. The produced material exhibits the widest transparent region (0.27-11.0 μm) among available oxides, the largest LDT (846 MW/cm) among materials that are transparent to 10 μm, and the strongest SHG effect among langasites. The discovery of LGSn facilitates the application of oxides as NLO crystals in the mid-IR spectral region beyond 10 μm. More generally, the developed strategy could be used to guide and accelerate the systematic discovery of functional materials through understanding the key structure-composition-property relationships using the predictive power of computational tools.

Dislocations that Decrease Size Mismatch within the Lattice Leading to Ultrawide Band Gap, Large Second‐Order Susceptibility, and High Nonlinear Optical Performance of AgGaS2

“…As the UV/Vis diffuse reflectance spectra of series of Li x Ag 1Àx GaS 2 (x = 0-0.60) show,t he more electropositive Li introduced, the wider the E g (Figure 3a). Theo bserved E g = 2.58 eV for x = 0a grees well with the reported value (2.56-2.75 eV [18][19][20] ). As expected, E g increases monotonously with the increase of the Li concentration, and finally reaches am aximum at the phase boundary,w here Li 0.60 Ag 0.40 GaS 2 achieves ar emarkably large E g of 3.40 eV,t he highest value ever known for AGSm aterial.…”

Lead Mixed Oxyhalides Satisfying All Fundamental Requirements for High‐Performance Mid‐Infrared Nonlinear Optical Materials

“…An emerging very effective approach for developing highperformance mid-IR NLO materials is to introduce special kinds of oxide-based systems containing relatively heavy atoms which can expand the IR transparent range.Promoted by this design strategy,several NLO oxides such as NaI 3 O 8 , [49] Pb 17 O 8 Cl 18 , [50] Bi(IO 3 )F 2 , [51] Li 3 VO 4 , [52] Cs 2 LiVO 4 , [53] La 3 SnGa 5 O 14 , [54] Li 2 ZrTeO 6 , [55] Rb 4 [57] and ABi 2 (IO 3 ) 2 F 5 (A = K, Rb,a nd Cs) [58] were proposed as attractive mid-IR NLO candidates. Although the transparent range of most of the reported NLO oxides only cover the atmospheric window of 3-5 mm, La 3 SnGa 5 O 14 and Pb 17 O 8 Cl 18 possess much wider IR transparencyu pt o1 2and 13.9 mm, respectively,w hich can be comparable to that of AgGaS 2 (13 mm We have paid special attention to lead mixed oxyhalide systems according to the following considerations:(1) As lead is av ery heavy element, the lead-oxygen and lead-halogen bonds have quite low vibration frequencies;t hus,c onsiderably wide IR transparencycan be attained.…”

Broadband CrOCl Saturable Absorber with a Spectral Region Extension to 10.6 µm

“…To the best of our knowledge, at present, CrOCl is the oxide‐based NLO material with the farthest IR cutoff edge. Compared to previously reported LGSn, CrOCl extends the IR absorption edge of oxide‐based NLO materials from 11 to 18 µm. The ultrawide available waveband from the near‐IR to far‐IR regions implies that CrOCl can be employed as an ideal IR NLO material.…”