β-Crystalline phase gallium oxide (β-GaO) is an ultrawide bandgap material with prospective applications in electronics and deep ultraviolet (DUV) optoelectronics and optics. The monoclinic crystal structure of β-GaO results in optical anisotropy to incident light with different polarization states. This attribute can lead to different optical applications in the DUV. In this article, we investigated the optical properties of β-GaO thin films grown by pulsed laser deposition technique on sapphire substrates with different crystallographic orientations. Marked in-plane polarization anisotropy, determined by reflectance and Raman spectroscopy, was observed for β-GaO films deposited on an -cut sapphire substrate. In contrast, isotropic optical properties were observed in β-GaO films deposited on a -cut sapphire substrate.
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http://dx.doi.org/10.1021/acsomega.3c10280 | DOI Listing |
J Imaging
December 2024
Process Analysis and Technology PA & T, Reutlingen University, Alteburgstraße 150, 72762 Reutlingen, Germany.
Ultraviolet (UV) hyperspectral imaging shows significant promise for the classification and quality assessment of raw cotton, a key material in the textile industry. This study evaluates the efficacy of UV hyperspectral imaging (225-408 nm) using two different light sources: xenon arc (XBO) and deuterium lamps, in comparison to NIR hyperspectral imaging. The aim is to determine which light source provides better differentiation between cotton types in UV hyperspectral imaging, as each interacts differently with the materials, potentially affecting imaging quality and classification accuracy.
View Article and Find Full Text PDFHere, we systematically investigate the effect of mesa/sub-mesa sidewall engineering on single-junction (SJ) and high-voltage (HV) deep ultraviolet light-emitting diodes (DUV LEDs). The configuration of ∼46° inclined angle of the mesa/sub-mesa sidewall and Al reflector optimally promotes light extraction of SJ/HV DUV LEDs. We further observe substantial improvements in the self-heating and external quantum efficiency (EQE) droop effects of HV DUV LEDs with an increasing number of sub-mesas.
View Article and Find Full Text PDFInverse design (ID) is a computational method that systematically explores a design space to find optimal device geometries based on specific performance criteria. In silicon photonics, ID often generates design features that degrade significantly due to the fabrication process, limiting the applicability of these devices in scalable fabrication. We demonstrate a solution to this performance degradation through fabrication-aware inverse design (FAID), integrating lithography models for deep-ultraviolet (DUV) lithography and electron-beam lithography (EBL) into the shape optimization approach of ID.
View Article and Find Full Text PDFThe cross talk and power consumption of the 2 × 2 optical switch is a key metric in the design of large-scale photonic integrated circuits (PICs). We build a theoretical model of a 2 × 2 Mach-Zehnder interferometer (MZI) optical switch, taking into account both imbalances in the arm loss and the coupler splitting ratio. The splitting ratio imbalance requirement for a given switch cross talk is summarized, which provides a guideline for the switch design.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Beijing Normal University, chemistry department, xinjiekou waidajie num 19, 100875, Beijing, CHINA.
Advancing laser technologies requires maximizing the anisotropy of crystalline media and overcoming current birefringence limitations. We introduce the strategy of linear π group anisotropic structure building units (ABUCB), leading to an unprecedented large birefringence (Δn), a record-high Δnobv. of 0.
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