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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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Large Enhancements in Optical and Piezoelectric Properties in Ferroelectric Zn 1‐ x Mg x O Thin Films through Engineering Electronic and Ionic Anharmonicities
Abstract Multifunctionality as a paradigm requires materials exhibiting multiple superior properties. Integrating second‐order optical nonlinearity and large bandgap with piezoelectricity can, for example, enable broadband, strain‐tunable photonics. Though very different phenomena at distinct frequencies, both second‐order optical nonlinearity and piezoelectricity are third‐rank polar tensors present only in acentric crystal structures. However, simultaneously enhancing both phenomena is highly challenging since it involves competing effects with tradeoffs. Recently, a large switchable ferroelectric polarization of ≈80 μC cm−2was reported in Zn1‐xMgxO films. Here, ferroelectric Zn1‐xMgxO is demonstrated to be a platform that hosts simultaneously a 30% increase in the electronic bandgap, a 50% enhancement in the second harmonic generation (SHG) coefficients, and a near 200% improvement in the piezoelectric coefficients over pure ZnO. These enhancements are shown to be due to a 400% increase in the electronic anharmonicity and a ≈200% decrease in the ionic anharmonicity with Mg substitution. Precisely controllable periodic ferroelectric domain gratings are demonstrated down to 800 nm domain width, enabling ultraviolet quasi‐phase‐matched optical harmonic generation as well as domain‐engineered piezoelectric devices.
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- PAR ID:
- 10469517
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Advanced Physics Research
- ISSN:
- 2751-1200
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/apxr.202300003
