“Three‐in‐One”: A New Hg‐Based Selenide Hg₇P₂Se₁₂ Exhibiting Wide Infrared Transparency Range and Strong Nonlinear Optical Effect

Abstract

The exploration of high‐performance mid‐ and far‐infrared (IR) nonlinear optical (NLO) crystals is an urgent need. Herein, a new Hg‐based selenide Hg7P2Se12 (HPSe) is designed and synthesized by a rigid and flexible units coupled strategy. It is interesting that in the compound, three types of NLO‐active units, including linear [HgSe2], triangular [HgSe3], and tetrahedral (MSe4) (M = Hg/P) groups, simultaneously exist. It shows a wide transparency range (0.84–22.8 µm), large SHG response (1 × AGS), high laser‐induced damage threshold (≈2 × AGS), and a large birefringence (0.102 @ 2090 nm). Moreover, the compound melts congruently along with good crystal growth habits, and single crystals with a maximum size of ≈7 × 5 × 2 mm3 are obtained. Theoretical analyses confirm that the large NLO response originates from the synergistic effects of Hg–Se units, (PSe4) and nonbonding electrons. The results indicate that HPSe is a promising mid‐ and far‐IR NLO material, and inspire a path to finding new classes of IR NLO materials that are different from traditional chalcopyrite materials by grouping the linear, planar, and tetrahedral units.

Wide band gap selenide infrared nonlinear optical materials AIIMg6Ga6Se16 with strong SHG responses and high laser-induced damage thresholds

“…51 To detect the origin of the NLO effect, the NLO coefficients and SHG density maps of the title compounds were investigated by DFT calculations. [52][53][54][55][56] As shown in Table S14 ] tetrahedral units (Fig. 4e, f and S6 †), matched with the anionic group theory promoted by Chen et al 57,58…”

“…To detect the origin of the NLO effect, the NLO coefficients and SHG density maps of the title compounds were investigated by DFT calculations. 52–56 As shown in Table S14, † the calculated NLO coefficients are d 11 = −11.05 and d 22 = 3.92 pm V −1 for CaMg 6 Ga 6 Se 16 , d 11 = −10.67 and d 22 = 3.93 pm V −1 for SrMg 6 Ga 6 Se 16 , d 11 = −10.58 and d 22 = 3.71 pm V −1 for BaMg 6 Ga 6 Se 16 , which match the experimental results in Fig. 3c .…”

“…51 To detect the origin of the NLO effect, the NLO coefficients and SHG density maps of the title compounds were investigated by DFT calculations. [52][53][54][55][56] As shown in Table S14…”

Pb3.5GeS4Br3: the first phase-matching thiogermanate halide infrared nonlinear optical material

“…[22][23][24] In general, an excellent IR NLO material should meet the following requirements: (1) large second-harmonic generation (SHG) response ≥ 0.5 × AGS, preferably ≥ 1.0 × AGS; (2) high LIDT ≥ 2.0 × AGS for high-power laser output; (3) wide optical transparent range that covers the two important atmospheric windows, 3-5 and/or 8-12 µm; (4) suitable birefringence (> 0.03) to achieve phase matching (PM), which is critical for the practical application of NLO materials; (5) good crystal growth habits and thermal stability. [25][26][27][28][29][30][31][32][33] However, it is challenging to satisfy these requirements in one compound. To explore new IR NLO materials, metal chalcohalides have received considerable attention due to their abundant structural diversity and adjustable optical properties.…”

β-CsHg2I5, a compound with rare [Hg2I5] dimers and large optical anisotropy

“…25 Remarkably, the 6s and 6p orbital energies of Hg with a unique d 10 electronic configuration are close to each other, 30,31 giving rise to various coordination modes between Hg and halides, such as linear [HgQ 2 ] (Q = halide elements), planar [HgQ 3 ] and tetrahedral [HgQ 4 ] units. 32,33 Similar to borates, the basic structural units can be further linked with each other to build new fundamental building block (FBB) groups theoretically. 34–37 Nevertheless, the [Hg x Q y ] units (Q = halide elements; x and y = integers and ≥2) are quite rare in the known Hg-based compounds, far less than the number of [B x O y ] units ( x and y = integers and ≥2) in the borates.…”