Giant Non‐Resonant Infrared Second Order Nonlinearity in γ ‐NaAsSe₂

Abstract

Infrared laser systems are vital for applications in spectroscopy, communications, and biomedical devices, where infrared nonlinear optical (NLO) crystals are required for broadband frequency down‐conversion. Such crystals need to have high non‐resonant NLO coefficients, a large bandgap, low absorption coefficient, and phase‐matchability among other competing demands; for example, a larger bandgap leads to smaller NLO coefficients. Here, the successful growth of single crystals of γ ‐NaAsSe2 that exhibit a giant second harmonic generation (SHG) susceptibility of d11 = 590 pm V−1 at 2 µm wavelength is reported; this is ~18 times larger than that of commercial AgGaSe2 while retaining a similar bandgap of ~1.87 eV, making it an outstanding candidate for quasi‐phase‐matched devices utilizing d11. In addition, γ ‐NaAsSe2 is both Type I and Type II phase‐matchable, and has a transparency range up to 16 µm wavelength. Thus, γ ‐NaAsSe2 is a promising bulk NLO crystal for infrared laser applications.

The Combination of Structure Prediction and Experiment for the Exploration of Alkali‐Earth Metal‐Contained Chalcopyrite‐Like IR Nonlinear Optical Material

“…[ 6 ] Among them, selenides normally exhibit wider IR transparent regions, larger SHG responses, and lower melting points, but smaller band gaps than sulfides. [ 7 ] Over the past decades, a plenty of selenides with good NLO properties like LiGaSe 2 , [ 8 ] α ‐BaGa 4 Se 7 , [ 9 ] β ‐BaGa 4 Se 7 , [ 10 ] β ‐BaGa 2 Se 4 , [ 11 ] Li 2 ZnMSe 4 (M = Ge, Sn), [ 12 ] Li 2 CdMSe 4 (M = Ge, Sn), [ 13 ] Li 2 In 2 MSe 6 (M = Si, Ge), [ 14 ] Na 4 MgM 2 Se 6 (M = Si, Ge), [ 15 ] BaGa 2 MSe 6 (M = Si, Ge), [ 16 ] γ ‐NaAsSe 2 , [ 17 ] Na 6 MSe 4 (M = Zn, Cd), [ 18 ] CsM 3 Se 6 (M = Ga/Sn, In/Sn), [ 19 ] and AgLiGa 2 Se 4 [ 20 ] have been designed and synthesized successfully. However, to enhance the LIDT, the band gaps in selenides are still highly expected to be further improved.…”

Strong In‐Plane Anisotropy and Giant Second Harmonic Generation Response of Organic Single‐Crystalline Microwire Arrays

“…[34,45,46] Combining the large second-order nonlinear coefficients of the OH1 and DAT2 microwires and the wide transmittance in the infrared region, they may have greater application potential in infrared frequency conversion. [47]…”

Heteroanionic Control of Exemplary Second-Harmonic Generation and Phase Matchability in 1D LiAsS2–xSex

“…Despite this phase transition, high-performing single crystals have been successfully grown, but they are air and water sensitive. 27 Cation substitution has been found to play an important role in tuning the band gap, SHG response, and [AsQ 2 ] − chain orientation in this family. Na substitution up to 40% into LiAsS 2 results in an increased SHG response (∼10× AgGaSe 2 in LiAsS 2 vs ∼30× AgGaSe 2 in Li 0.6 Na 0.4 AsS 2 ) but further Na substitution results in the centrosymmetric Pbca space group.…”

“…Despite the structure-directing nature of As 3+ and the covalency of As–Q bonds, relatively few studies have focused on chalcoarsenates, and even fewer have studied chalcoarsenates as NLO-active materials. Table shows selected chalcoarsenates, their relative SHG intensities, and band gaps. − …”

“…γ-NaAsSe 2 undergoes a NCS-centrosymmetric (NCS–CS) phase transition upon cooling from the melt. Despite this phase transition, high-performing single crystals have been successfully grown, but they are air and water sensitive . Cation substitution has been found to play an important role in tuning the band gap, SHG response, and [AsQ 2 ] − chain orientation in this family.…”