We demonstrate the anti-reflection properties of lithographically defined subwavelength gratings applied to the facets of integrated waveguides realized in the InP membrane-on-silicon platform. The subwavelength gratings are based on the gradient index effect to create a smooth index transition between the core material and air, making it possible to obtain reflections below -30 at a wavelength of 1550 nm for both TE and TM polarized modes, as shown by 3D finite-difference time-domain simulations. Characterizations performed using Mach-Zehnder interferometers as test structures show relative reflections as low as -25, confirming the effectiveness of the technique.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1364/OL.431353 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Talbot effect based sensor measuring grating period change in subwavelength range.
Sci Rep
December 2024
Physical Research Laboratory, Ahmedabad, Gujarat, 380009, India.
Talbot length, the distance between two consecutive self-image planes along the propagation axis for a periodic diffraction object (grating) illuminated by a plane wave, depends on the period of the object and the wavelength of illumination. This property makes the Talbot effect a straightforward technique for measuring the period of a periodic object (grating) by accurately determining the Talbot length for a given illumination wavelength. However, since the Talbot length scale is proportional to the square of the grating period, traditional Talbot techniques face challenges when dealing with smaller grating periods and minor changes in the grating period.
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 PDFOblique Deposited Ultra-Thin Silver Films on Polymer Gratings for Sensitive SERS Performance.
Nanomaterials (Basel)
November 2024
Department of Electro-Optical Engineering, National Taipei University of Technology, Taipei 106, Taiwan.
A small amount of silver was obliquely deposited onto a polymer subwavelength grating to form a metasurface that comprised silver split-tubes. An ultra-thin silver film with a monitor-controlled thickness of 20 nm at the corner of each ridge of the grating provided the most sensitive surface-enhanced Raman scattering (SERS) measurements. An excitation laser beam that was incident from the substrate provided similar or better SERS enhancement than did the general configuration with the laser beam incident directly on the surface of the nanostructure.
View Article and Find Full Text PDFControl of transverse modes in the oxide-confined vertical-cavity surface-emitting laser (VCSEL) is a key issue. We demonstrate a VCSEL with a double heterostructure high-contrast grating (HCG) as the top mirror to control the transverse mode characteristics. Compared with the common HCG-VCSEL with a uniform HCG, theoretically the proposed double heterostructure HCG-VCSEL can suppress the higher-order transverse modes.
View Article and Find Full Text PDFArticle Synopsis
- Kirchhoff's law outlines the fundamental limits of thermal radiation, suggesting that breaking the principle of electromagnetic reciprocity could enhance thermal efficiency in engineering.
- A new 1D photonic crystal design, using Weyl semimetals and dielectric layers, was created to optimize nonreciprocal infrared radiation absorptance without needing additional coupling structures like gratings.
- The design process utilized genetic algorithms for global optimization and gradient ascent for local enhancement, resulting in a compact eight-layer magnetophotonic crystal that improves absorptance while reducing unwanted reciprocal light absorption.
Want 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!