Experimental results on wavelength-dependent angular dispersion in InGaAsP triangular lattice planar photonic crystals are presented. An abrupt variation of the angular dispersion is observed for TM-polarized waves whose frequencies are comprised between those of the fourth and sixth allowed bands. According to the crystal period, the measured angle of refraction is found to either decrease or increase by 30 degrees within a wavelength range smaller than 30 nm. Experimental results are reproduced well from 2D finite difference time domain calculations. The observed phenomena are interpreted from the coupling of the incident light to different modes of the photonic crystal that travel with different group velocities and propagate in different directions within the crystal. Mode dispersion curves and mode patterns are calculated along with isofrequency curves to support this explanation. The observed discontinuous wavelength super-refraction opens a new approach to the application of superprisms.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1364/oe.14.002003 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Disorder-order transition-induced unusual bandgap bowing effect of tin-lead mixed perovskites.
Sci Adv
January 2025
Department of Materials Science and Engineering, Shenzhen Key Laboratory of Full Spectral Solar Electricity Generation (FSSEG), Southern University of Science and Technology, No. 1088, Xueyuan Rd., Shenzhen 518055, Guangdong, China.
Owing to the predominant merit of tunable bandgaps, tin-lead mixed perovskites have shown great potentials in realizing near-infrared optoelectronics and are receiving increasing attention. However, despite the merit, there is still a lack of fundamental understanding of the bandgap variation as a function of Sn/Pb ratio, mainly because the films are easy to segregate in terms of both composition and phase. Here, we report a fully stoichiometric synthesis of monocrystalline FAPbSnI nanocrystals as well as their atomic-scale imaging.
View Article and Find Full Text PDFMultifocal metalenses are effective elements for longitudinal light field modulation and have important applications in long-focal depth imaging and three-dimensional display. However, the forward design method is subject to destructive interference generated by phase discontinuity, and cannot achieve high-efficiency, tunable multifocal metalenses. Therefore, we propose an efficient and tunable inverse design framework based on the adjoint method and gradient strategy, transforming light field modulation into mathematical optimization of nonlinear constraints.
View Article and Find Full Text PDFTemporal Refraction in an Acoustic Phononic Lattice.
Phys Rev Lett
August 2024
Department of Mechanical and Civil Engineering, California Institute of Technology, Pasadena, California 91125, USA.
In this Letter, we present the first experimental demonstration of the temporal refraction of acoustic waves in a phononic lattice. A step change in grounding stiffness results in a discontinuous change in group velocity across a so-called temporal boundary. This leads to frequency translation of incident signals, which maintain constant wavelength.
View Article and Find Full Text PDFArticle Synopsis
- Fabrication imperfections like roughness and discontinuities in photonic wire waveguides can severely impact their performance, leading to high insertion losses and reduced production efficiency.
- The study focuses on a new platform using silicon nano-pillars to create a sub-wavelength grating waveguide that exhibits robustness to these types of discontinuities.
- Experimental results show that this innovative waveguide design experiences significantly lower transmission losses, measuring less than 2.2 dB for certain discontinuities, making it a promising solution for developing low-loss optical waveguides across the telecommunication spectrum.
Blue Wavelength of Scanning Laser Ophthalmoscope Potentially Detects Arteriosclerotic Lesions in Diabetic Retinopathy.
Diagnostics (Basel)
July 2024
Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, Tokyo 113-8510, Japan.
(1) Background: The fundus examination is one of the best and popular methods in the assessment of vascular status in the human body. Direct viewing of retinal vessels by ophthalmoscopy has been utilized in judging hypertensive change or arteriosclerosis. Recently, fundus imaging with the non-mydriatic scanning laser ophthalmoscope (SLO) has been widely used in ophthalmological clinics since it has multimodal functions for optical coherence tomography or angiography with contrast agent dye.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!