We study the exciton contribution to the third-order optical susceptibility of one-dimensional semiconductor quantum dots and show that the screening of the electron-hole interaction has a strong influence on the nonlinear optical properties in the weak confinement regime. Based on a density matrix formulation, we estimate the spectrum of the third-order optical susceptibility and its contribution to the refraction index and absorption coefficient. In particular, we show that the multipeaked spectrum of the nonlinear susceptibility, which results from the hydrogenoid character of the exciton eigenstates for a purely Coulombian electron-hole coupling, is reverted towards a single peaked structure as the interaction becomes strongly screened, thus leading to a substantial enhancement of the nonlinear optical properties of semiconductor quantum dots.
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http://dx.doi.org/10.1364/OE.22.028270 | DOI Listing |
Nat Nanotechnol
January 2025
Department of Chemistry, Columbia University, New York, NY, USA.
Van der Waals (vdW) semiconductors have emerged as promising platforms for efficient nonlinear optical conversion, including harmonic and entangled photon generation. Although major efforts are devoted to integrating vdW materials in nanoscale waveguides for miniaturization, the realization of efficient, phase-matched conversion in these platforms remains challenging. Here, to address this challenge, we report a far-field ultrafast imaging method to track the propagation of both fundamental and harmonic waves within vdW waveguides with femtosecond and sub-50 nanometre spatiotemporal precision.
View Article and Find Full Text PDFEnviron Int
January 2025
Joint International Research Laboratory of Environment and Health, Ministry of Education, Guangdong Provincial Engineering Technology Research Center of Environmental Pollution and Health Risk Assessment, Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou 510080 China. Electronic address:
Background: Exposure to fine particulate matter (PM) has been linked to visual impairment. Nevertheless, evidence associating PM constituents with visual impairment in schoolchildren is sparse.
Objectives: To explore the effects of long-term exposure to PM and its constituents on visual impairment.
Radiat Environ Biophys
January 2025
Laboratory of Health Sciences and Technologies, Higher Institute of Health Sciences, Hassan First University, Settat, Morocco.
This study assesses radiation doses in multi-slice computed tomography (CT) using epoxy resin and PMMA phantoms, focusing on the relationship between TAR (tissue air ratio) and kilovoltage peak (kVp). The research was conducted using a Hitachi Supria 16-slice CT scanner. An epoxy resin phantom was fabricated from commercially available materials, to simulate human tissue.
View Article and Find Full Text PDFNano Lett
January 2025
Facultad de Ciencias Exactas y Naturales, Departamento de Física, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina.
Nanostructured high-index dielectrics have shown great promise as low-loss photonic platforms for wavefront control and enhancing optical nonlinearities. However, their potential as optomechanical resonators has remained unexplored. In this work, we investigate the generation and detection of coherent acoustic phonons in individual crystalline gallium phosphide nanodisks on silica in a pump-probe configuration.
View Article and Find Full Text PDFBMC Public Health
January 2025
Department of Ophthalmology, Guangdong Eye Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, 106 Zhongshan Er Road, Guangzhou, 510080, Guangdong, PR China.
Background: Traffic-related air pollution especially in highly socioeconomically developed megacity is usually considered as a severe problem leading to inevitable adverse health outcomes. This study aimed to investigate the associations between traffic-related air pollutants with risk of dry eye disease (DED) outpatient visits in a megacity (Guangzhou) along the subtropical coast in South China.
Methods: Daily data on DED outpatient visits and environmental variables from 1 January 2014 to 31 December 2020 in Guangzhou were obtained.
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