We study second harmonic generation in a 2-D photonic crystal with the pump field tuned at the Dirac point of the structure. The simultaneous generation of both forward and backward phase-matched second harmonic is achieved by exploiting a peculiar regime in which the interacting waves have zero phase velocity in the lattice. This regime can be attained even when strong material dispersion is present and therefore lends itself well to be implemented in semiconductor-based frequency conversion devices. A comparison between this method and the quasi-phase-matching technique is also presented.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1364/OE.22.006381 | DOI Listing |
Inorg Chem
January 2025
School of Physics and Materials Science, Changji University, Changji 831100, People's Republic of China.
Finding novel efficient nonlinear optical materials with large second-order nonlinearity for the UV spectral range remains a formidable challenge, especially for silicate systems. Using a high-temperature solid reaction in a tight vacuum environment, two ultraviolet nonlinear optical materials with a moderate second harmonic generation (SHG) response have been created: PbSiOC and PbCaSiO. The SHG values they computed are roughly 2.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
IMoPA, UMR 7365, CNRS-Université de Lorraine, Nancy, France.
Background: While Alzheimer Disease (AD) patients' difficulty to recognize face identity (Werheid & Clare, 2007) has been mainly attributed to episodic and semantic memory impairments, these patients can also show abnormal difficulties at matching of unfamiliar faces for their identity, suggesting impaired perceptual function (Lavallée et al., 2016). However, since this latter evidence is based on explicit behavioural measures, the difficulties of AD patients can be due to many factors (e.
View Article and Find Full Text PDFInorg Chem
January 2025
School of Chemistry and Chemical Engineering, Nanchang University, Nanchang 330031, P. R. China.
Organic-inorganic hybrid lead halides have been extensively studied due to their outstanding physical properties and diverse compositional elements. However, environmentally benign tin-based hybrids with remarkable flexibility in bandgap engineering have been less investigated. Herein, we report the successful design and synthesis of three tin-based organic-inorganic hybrid compounds through precise molecular modification: [Me(i-Pr)N][SnBr] (), [MeCHCl(i-Pr)N][SnBr] (), and [MeCHBr(i-Pr-Br)N][SnBr] ().
View Article and Find Full Text PDFACS Nano
January 2025
Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China.
Moiré superlattices, created by stacking different van der Waals materials at twist angles, have emerged as a versatile platform for exploring intriguing phenomena such as topological properties, superconductivity, the quantum anomalous Hall effect, and the unconventional Stark effect. Additionally, the formation of moiré superlattice potential can generate spontaneous symmetry breaking, leading to an anisotropic optical response and electronic transport behavior. Herein, we propose a two-step chemical vapor deposition (CVD) strategy for synthesizing WS/SbS moiré superlattices.
View Article and Find Full Text PDFAnal Chem
January 2025
School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, Liaoning, China.
A cantilever-enhanced fiber-optic photoacoustic (PA) spectrophone is reported for trace gas detection at a low-pressure environment. A cantilever-based fiber-optic Fabry-Perot (F-P) interferometer (FPI) is utilized for simultaneous measurement of air pressure and PA pressure. Since the cantilever resonance frequency follows air pressure linearly, the fundamental frequency intensity modulation (1-IM) technique is applied to scan the frequency response of the solid PA signal from tube wall absorption for tracking the cantilever resonance frequency in real time.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!