The Rise of Infrared Nonlinear Optical Pnictides: Advances and Outlooks

Abstract

Infrared (IR) nonlinear optical (NLO) materials are the core devices to realize IR laser output, which are of vital importance in civilian and military fields. Non‐centrosymmetric chalcogenide and pnictide compounds have already been widely accepted as favorable systems for IR‐NLO materials. Compared to the extensively investigated IR‐NLO chalcogenides during the past few decades, the research of non‐centrosymmetric phosphides as IR‐NLO materials is relatively scarce. In this frontier article, the recent progress of pnictides as emerging IR‐NLO candidates has been highlighted based on the perspective of new crystal exploration. These IR‐NLO pnictides recently reported were divided into three groups from binary to quaternary according to their chemical compositions. The synthetic methods, structural chemistry, and structure‐activity relationships are analyzed and summarized in detail. Finally, current problems and the future development of this field are also proposed.

From Cc to P63mc: Structural Variation in La3S2Cl2[SbS3] and La3OSCl2[SbS3] Induced by the Isovalent Anion Substitution

“…Moreover, compounds with NCS lattice have attracted increasing interest for their potential applications in nonlinear optical (NLO) crystals. In order to predesign NCS compounds, various asymmetric anionic units have been employed. − However, rational design of NCS materials is still a challenging task, because of the unpredictability of the packing of the anionic asymmetric polyhedra. In other words, the symmetry in the overall structure is highly dependent not only on the anionic asymmetric polyhedra but also on the cationic counterparts.…”

Quaternary Noncentrosymmetric Rare-Earth Sulfides Ba4RE2Cd3S10 (RE = Sm, Gd, or Tb): A Joint Experimental and Theoretical Investigation

“…NLO materials must possess noncentrosymmetric (NCS) structures . Combining various asymmetric building units (ABUs) into the structure is an effective method for increasing the chance of obtaining the NCS structure and improving the NLO performance. − So far, the known NLO-active ABUs in the IR range mainly include d 10 transition-metal-centered tetrahedra (e.g., AgQ 4 , CdQ 4 , and HgQ 4 , where Q = chalcogen), main-group-metal-centered tetrahedra (e.g., GaQ 4 , PQ 4 , GeQ 4 , and SnQ 4 ), triangular anionic groups (e.g., BS 3 , AsS 3 , and SbS 3 ), and rare-earth-metal-centered polyhedra (e.g., REQ 6 , REQ 8 , and REQ 10 ). Among them, the RE/M/TM/Q system (RE = rare-earth metals; M = main-group metals; TM = d-block transition metals; and Q = chalcogen) has a bright future in the IR-NLO field.…”

Predicting Diamond-like Nitrides as Infrared Nonlinear Optical Materials with High Thermal Conductivity

“…For several decades, the exploration of infrared NLO candidate materials has mainly focused on: halides, oxyhalides, chalcohalides, oxides, pnictides, and chalcogenides. − Among them, although some halides, oxyhalides, chalcohalides, and oxides have relatively large band gaps, they exhibit smaller NLO coefficients than those of chalcogenides and pnictides. For pnictides, such as ZnGeP 2 , CdSiP 2 , and CdGeAs 2 , they usually have very large NLO coefficients but narrow band gaps. Up to now, chalcogenides are one of the most exploratory system as infrared NLO materials, while the commercial chalcogenides AgGaS 2 and AgGaSe 2 have low thermal conductivity and low laser damage threshold.…”

“…Unfortunately, infrared NLO materials commercially available at present are diamond-like compounds AgGa Q 2 ( Q = S, Se) , and ZnGeP 2 , which scarcely satisfy the infrared laser demands because of their low laser damage threshold or two-photon absorption. For several decades, the exploration of infrared NLO candidate materials has mainly focused on: halides, oxyhalides, chalcohalides, oxides, pnictides, and chalcogenides. − Among them, although some halides, oxyhalides, chalcohalides, and oxides have relatively large band gaps, they exhibit smaller NLO coefficients than those of chalcogenides and pnictides. For pnictides, such as ZnGeP 2 , CdSiP 2 , and CdGeAs 2 , they usually have very large NLO coefficients but narrow band gaps.…”