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Abstract Discovery of new materials with enhanced optical properties in the visible and UV‐C range can impact applications in lasers, nonlinear optics, and quantum optics. Here, the optical floating zone growth of a family of rare earth borates,RBa3(B3O6)3(R= Nd, Sm, Tb, Dy, and Er), with promising linear and nonlinear optical (NLO) properties is reported. Although previously identified to be centrosymmetric, the X‐ray analysis combined with optical second harmonic generation (SHG) assigns the noncentrosymmetricPspace group to these crystals. Characterization of linear optical properties reveals a direct bandgap of ≈5.61–5.72 eV and strong photoluminescence in both the visible and mid‐IR regions. Anisotropic linear and nonlinear optical characterization reveals both Type‐I and Type‐II SHG phase matchability, with the highest effective phase‐matched SHG coefficient of 1.2 pm V−1at 800‐nm fundamental wavelength (for DyBa3(B3O6)3), comparable to β‐BaB2O4(phase‐matchedd22≈ 1.9 pm V−1). Laser‐induced surface damage threshold for these environmentally stable crystals is 650–900 GW cm−2, which is four to five times higher than that of β‐BaB2O4, thus providing an opportunity to pump with significantly higher power to generate about six to seven times stronger SHG light. Since the SHG arises from disorder on the Ba‐site, significantly larger SHG coefficients may be realized by “poling” the crystals to align the Ba displacements. These properties motivate further development of this crystal family for laser and wide bandgap NLO applications.
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Stabilization of the Polar Structure and Giant Second‐Order Nonlinear Response of Single Crystal γ‐NaAs 0.95 Sb 0.05 Se 2
Abstract The dearth of suitable materials significantly restricts the practical development of infrared (IR) laser systems with highly efficient and broadband tuning. Recently, γ‐NaAsSe2is reported, and it exhibits a large nonlinear second‐harmonic generation (SHG) coefficient of 590 pm V−1at 2 µm. However, the crystal growth of γ‐NaAsSe2is challenging because it undergoes a phase transition to centrosymmetric δ‐NaAsSe2. Herein, the stabilization of non‐centrosymmetric γ‐NaAsSe2by doping the As site with Sb, which results in γ‐NaAs0.95Sb0.05Se2is reported. The congruent melting behavior is confirmed by differential thermal analysis with a melting temperature of 450 °C and crystallization temperature of 415 °C. Single crystals with dimensions of 3 mm × 2 mm are successfully obtained via zone refining and the Bridgman method. The purification of the material plays a significant role in crystal growth and results in a bandgap of 1.78 eV and thermal conductivity of 0.79 Wm−1K−1. The single‐crystal SHG coefficient of γ‐NaAs0.95Sb0.05Se2exhibits an enormous value of |d11| = 648 ± 74 pm V−1, which is comparable to that of γ‐NaAsSe2and ≈20× larger than that of AgGaSe2. The bandgap of γ‐NaAs0.95Sb0.05Se2(1.78 eV) is similar to that of AgGaSe2, thus rendering it highly attractive as a high‐performing nonlinear optical material.
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- Award ID(s):
- 2039351
- PAR ID:
- 10386460
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 33
- Issue:
- 9
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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