RESUMO
The balance between second harmonic generation (SHG) intensity and laser-induced damage threshold (LIDT), together with phase-matchable behavior, is the key point for exploration of novel nonlinear optical (NLO) materials. In this work, the NLO property of defect wurtzite-type hexagonal-In2Se3 (γ) is extensively explored first. It exhibits a strong SHG intensity of 2.6 × AgGaS2 (AGS) at 2.1 µm, and a high powder LIDT of 7.3 × AGS. From wurtzite to γ-In2Se3, the birefringence changes from 0.003 to 0.075, resulting in the phase-matchable phenomenon of γ-In2Se3. This is well ascribed to the contribution of the unique InSe5 unit in γ-In2Se3 from the result of birefringence calculation and analysis.
RESUMO
Partial substitution of Ba by K in the Ba sites of BaGa2Se4 creates a new selenide (K0.38Ba0.81)Ga2Se4 (1), which is crystallized in the noncentrosymmetric space group I4cm, different from the centric structures of all the ternary MI-MIII2-Q4 (MII = divalent Sr, Ba, Pb, Sn, Eu; MIII = trivalent Ga, In; Q = S and Se) chalcogenides. Its 1D structure features {[GaSe2]-}∞ chains, and K/Ba occupying the interchain cavities as the counter cations. Its powder sample demonstrates a second-harmonic generation intensity which is around 0.9 times that of AgGaS2 at 2.1 µm, and a laser-induced damage threshold which is 13.4 times that of AgGaS2. DFT calculations on its electronic structure and optical properties were also performed.
RESUMO
The deficiency of nonlinear-optical (NLO) materials in the IR region inspires strong research interest in this field. Here, Sn2Ga2S5 (1), crystallizing in the orthorhombic Pna21 space group, demonstrates obvious NLO activity, around a maximum of 1.6 times that of AgGaS2 and a strong laser-induced damage threshold of 9.7 times that of AGS. 1 represents the first NLO-active compound in the MII2MIII2Q5 (MII = divalent Ca, Sr, Ba, Pb, Sn, and Eu; MIII = B, Al, Ga, and In; Q = S and Se) family. The NLO performances of 1 are systematically studied experimentally and theoretically.
RESUMO
A big challenge for nonlinear optical (NLO) materials is the application in high power lasers, which needs the simultaneous occurrence of large second harmonic generation (SHG) and high laser induced damage threshold (LIDT). Herein we report the preparation of a new Ga2 Se3 phase, which shows the SHG intensities of around 2.3â times and the LIDT of around 16.7â times those of AgGaS2 (AGS), respectively. In addition, its IR transparent window ca. 0.59-25â µm is also significantly wider than that of AGS (ca. 0.48-≈11.4â µm). The occurrence of the strong SHG responses and good phase-matching indicate that the structure of the new Ga2 Se3 phase can only be non-centrosymmetric and have a lower symmetry than the cubic γ-phase. The observed excellent SHG and phase-matching properties are consistent with our diffraction experiments and can be well explained by using the orthorhombic models obtained through our high throughput simulations.
RESUMO
Two isostructural adducts CHI3·(S8)3 (1) and AsI3·(S8)3 (2) are synthesized by a simple solution method. Both of them crystallize in noncentrosymmetric R3 m, featuring van der Waals interaction linked CHI3 tetrahedra or SbI3 trigonal pyramids with crown-like S8 molecules. Both 1 and 2 show strong SHG responses and phase matchability under either 1.064 or 2.1 µm. The results of DFT calculations indicate that the electron transfer happens from S-3p to I-5p orbitals, and both of them demonstrate indirect band gaps. The NLO effects of 1 and 2 are almost fully contributed from the CHI3 or AsI3 units. Compared with AgGaS2, their powder laser damage thresholds are ca. 15 and 51 times higher.
RESUMO
A noncentrosymmetric adduct, SbI3·(S8)3, is obtained by a facile solution method. It crystallizes in the trigonal space group R3 m, and its structure features van der Waals force connected, isolated trigonal-pyramidal SbI3 and chairlike S8 units. SbI3·(S8)3 exhibits strong second-harmonic-generation responses around 4 times that of KH2PO4 (1.064 µm) and 1 times that of AgGaS2 (AGS; 2.1 µm) at 210-250 µm, respectively. Under both laser-radiation wavelengths, it exhibits type I phase-matching behavior. Its laser-induced damage threshold is measured to be around 26 times that of AGS under 1.064 µm. To better understand these optical data, theoretical calculations are performed to address its electronic structure and optical properties.
