We analytically and numerically investigate surface second-harmonic generation (SHG) from a stack of dielectric layers. We develop a theoretical formalism based on the transfer matrix method for the calculation of the surface-driven second-harmonic radiation from multilayer structures and elaborate it for the case of ultrathin dielectric layers using a power series expansion to derive the effective surface nonlinear tensor for the whole stack. We show that for deeply subwavelength thicknesses of the layers the surface responses from all interfaces can efficiently sum up, leading to largely enhanced efficiency of SHG. As a result, such surface-driven nonlinearity can become comparable to the bulk nonlinearity in noncentrosymmetric semiconductors and can yield high performance for nonlinear nanophotonic applications.
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http://dx.doi.org/10.1364/OE.417066 | DOI Listing |
Sci Rep
January 2025
Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, 528 Zhangheng Road, Pudong New Area, Shanghai, 201203, China.
A major histologic feature of cirrhosis is the loss of liver architecture with collapse of tissue and vascular changes per unit. We developed qVessel to quantify the arterial density (AD) in liver biopsies with chronic disease of varied etiology and stage. 46 needle liver biopsy samples with chronic hepatitis B (CHB), 48 with primary biliary cholangitis (PBC) and 43 with metabolic dysfunction-associated steatotic liver disease (MASLD) were collected at the Shuguang Hospital.
View Article and Find Full Text PDFActa Biomater
January 2025
Department of Cardiology, Biomedical Engineering, Cardiovascular Institute, Thorax Center, Erasmus MC, Rotterdam, the Netherlands.
Many cardiovascular events are triggered by fibrous cap rupture of an atherosclerotic plaque in arteries. However, cap rupture, including the impact of the cap's structural components, is poorly understood. To obtain better mechanistic insights in a biologically and mechanically controlled environment, we previously developed a tissue-engineered fibrous cap model.
View Article and Find Full Text PDFNanomaterials (Basel)
January 2025
College of Electronic and Optical Engineering and College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing 210023, China.
Silver gallium sulfide (AgGaS) is a ternary ABX-type semiconductor featuring a direct bandgap and high chemical stability. Structurally resembling diamond, AgGaS has gained considerable attention as a highly promising material for nonlinear optical applications such as second harmonic generation and optical parametric oscillation. In attempts to expand the research scope, on the one hand, AgGaS-derived bulk materials with similar diamond-like configurations have been investigated for the enhancement of nonlinear optics performance, especially the improvement of laser-induced damage thresholds and/or nonlinear coefficients; on the other hand, nanoscale AgGaS and its derivatives have been synthesized with sizes as low as the exciton Bohr radius for the realization of potential applications in the fields of optoelectronics and lighting.
View Article and Find Full Text PDFChem Sci
January 2025
Guangxi Key Laboratory of Electrochemical Energy Materials, School of Chemistry and Chemical Engineering, Guangxi University Nanning Guangxi 530004 China
Acentric crystalline materials are the cornerstone of numerous cutting-edge technologies and have been highly sought-after, but they are difficult to construct controllably. Herein, by introducing a new p-block element to break the symmetrical environment of the d transition metal in the centric matrix TiTeO, a novel acentric tellurite sulfate, namely Ti(TeO)(SO), was successfully constructed. In its structure, two types of p-block element-centered oxo-anionic groups, [TeO] and [SO], endow [TiO] with an out-of-center distortion along the local C[111] direction, which is rare in titanium oxides containing a lone-pair cation.
View Article and Find Full Text PDFChem Sci
January 2025
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou 350002 China
Traditional tetrahedral-based mid-to-far infrared (MFIR) nonlinear optical (NLO) crystals often face limitations due to the optical anisotropy constraints imposed by their highly symmetric structures. In contrast, the relatively rare trigonal pyramidal [TeS] functional unit characterized by its asymmetric structure and stereochemically active lone pair (SCALP), offers improved optical anisotropy, hyperpolarizability and a broader IR transparency range. Despite its potential, synthetic challenges have hindered the development of MFIR NLO crystals that incorporate this unit, with only one example reported to date.
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