SnP₂S₆: A Promising Infrared Nonlinear Optical Crystal with Strong Nonresonant Second Harmonic Generation and Phase-Matchability

Abstract

High-power infrared laser systems with broadband tunability are of great importance due to their wide range of applications in spectroscopy and free-space communications. These systems require nonlinear optical (NLO) crystals for wavelength up/down conversion using sum/difference frequency generation, respectively. NLO crystals need to satisfy many competing criteria, including large nonlinear optical susceptibility, large laser induced damage threshold (LIDT), wide transparency range and phase-matchability. Here, we report bulk single crystals of SnP2S6 with a large non-resonant SHG coefficient of d33 = 53 pm V −1 at 1550nm and a large LIDT of 350 GW cm -2 for femtosecond laser pulses. It also exhibits a broad transparency range from 0.54μm to 8.5μm (bandgap of ~2.3 eV) and can be both Type I and Type II phase-matched. The complete linear and SHG tensors are measured as well as predicted by first principles calculations, and they are in excellent agreement. A proximate double-resonance condition in the electronic band structure for both the fundamental and the SHG light is shown to enhance the non-resonant SHG response. Therefore, SnP2S6 is an outstanding candidate for infrared laser applications.

SnP2Se6: A Chiral 2D Semiconductor for High-Performance Electronics and Optoelectronics

“…In this case, the bandgap is enlarged to 0.84 eV compared to 0.55 eV for the bulk, albeit significantly smaller than the calculated bandgap of 2.23 eV for an SnP2S6 monolayer. 28,32,33 The contributions to the VBM and CBM, as seen from the projected density of states for the monolayer, were similar to the bulk phase. In other words, the VBM and CBM consist mainly of Se 4p and Sn 5s orbitals, respectively.…”

“…This family of vdW materials includes ferroelectric, magnetic, and half-metal materials, Mott insulators, nonlinear optical crystals, and semiconductors, with selenides having narrower bandgaps than sulfides. 15,16,17,21,22,23,24,25,26,27,28 Here, we report the synthesis of a new layered chalcophosphate, SnP2Se6, using chemical vapor transport (CVT) and a P2Se5-based flux method. SnP2Se6 melts incongruently into Sn2P2Se6 and a P/Se glass at ≈408 °C.…”

“…S6), significantly redshifted compared to the sulfide analog (≈2.3 eV). 28,35 Finally, the work function of SnP2Se6 was measured to be 5.72 eV based on the photoemission yield spectra (Supplementary Fig. S7b).…”

Revisiting two thiophosphate compounds constituting d0transition metal HfP2S6and d10transition metal α-Ag4P2S6as multifunctional materials for combining second harmonic generation response and photocurrent response

“…Thiophosphates, which combine both phosphorus and sulfur, are demonstrated to be good candidates for infrared nonlinear optical materials, where the promising properties originate from structure and chemical flexibility. The flexible [P x S y ] motifs interact with various cations generating many promising nonlinear optical materials including Rb 2 Ga 2 P 2 S 9 , 33 [K 3 Cl][Ga 3 PS 8 ], 34 [Rb 3 Cl][Ga 3 PS 8 ], 34 [K 3 Br][Ga 3 PS 8 ], 34 [Rb 3 Br][Ga 3 PS 8 ], 34 LiZnPS 4 , 35 CuZnPS 4 , 36 CuHgPS 4 , 37 AgZnPS 4 , 35 Ag 3 PS 4 , 38 LiGa 2 PS 6 , 39 AgGa 2 PS 6 , 40 LiCd 3 PS 6 , 39 CuCd 3 PS 6 , 41 AgCd 3 PS 6 , 42 Zn 3 P 2 S 8 , 43 Hg 3 P 2 S 8 , 44 Sn 2 P 2 S 6 , 45–47 KBiP 2 S 6 , 48 K 2 BaP 2 S 6 , 49 KSbP 2 S 6 , 49 Pb 2 P 2 S 6 , 50 α-Ba 2 P 2 S 6 , 50 Pb 3 P 2 S 8 , 51 RbBiP 2 S 6 , 52 Eu 2 P 2 S 6 , 53 Hg 2 P 2 S 6 , 54 ASrPS 4 (A = Li, Na, K, Rb, Cs), 55 AAg 2 PS 4 (A = K, Na/K), 56 etc. From the perspective of the constituting cations, the most explored cations for thiophosphate nonlinear optical materials are alkali metals and d 10 transition metals.…”

AAg3Ga8Se14 (A = Rb, Cs): second-harmonic generation responses realized through the parallel arrangement of AgSe4 and GaSe4 tetrahedrons

“…Nonlinear optical (NLO) materials play an important and irreplaceable role as the core devices of all-solid-state lasers due to their excellent frequency conversion functions. 1–6 Several oxide NLO materials, such as β-BaB 2 O 4 , 7 LiB 3 O 5 , 8 KH 2 PO 4 , 9 and KTiOPO 4 10 are currently used in the UV/Vis but not in the infrared (IR) range because they absorb chemical bonds in the IR range. Commercial IR NLO materials are rare, and include ZnGeP 2 (ZGP), 11 AgGaS 2 (AGS), 12 and AgGaSe 2 (AGSe).…”