Silicon waveguides move us closer to faster, light-based logic circuits  February 8, 2021 Wiring up the transistors of an optical circuit with silicon waveguides is an important requirement to make compact, highly integrated chips. However, silicon is a strong absorber of visible light. To circumvent the absorption issue researchers in Switzerland used high contrast grating consisting of nanometer sized “posts” lined up in such a way that light passing through the posts interferes destructively with light passing between posts making sure that no light can “leak” through the grating. Most of the light gets reflected inside the waveguide. They showed that there was a loss of only 13 percent […]

Sculpting a Waveguide with Light

American Physical Society August 14, 2020 Accelerating charged particles using intense laser pulses instead of radio-frequency fields could dramatically reduce the sizes of high-energy particle accelerators. Researchers at the University of Maryland prepared a longer, more controllable, and less leaky waveguide using two consecutive laser pulses that approximate Bessel beams, which are waveforms that do not spread out as they propagate. The first pulse creates the core of the waveguide. The second pulse creates the cladding. With this independent preparation of core and cladding, the team could form a waveguide with finely tunable parameters, such as the diameter and the […]

A Graphene Waveguide For Electrons

American physical Society  November 22, 2019 An electron carrying information in its quantum state and acting according to its wave nature can travel though a waveguide, but if multiple modes are available, then the electron can switch between them and lose information. An international team of researchers (USA – MIT, Japan, France) designed a device that includes a graphene flake sandwiched between two insulating sheets. On top of this structure sits a single carbon nanotube. A voltage applied across the CNT induces an electrostatic potential shaped like a rain gutter that extends down into the flake. The potential traps the […]

Thinnest optical waveguide channels light within just three layers of atoms

Science Daily  August 12, 2019 A team of researchers in the US (UC San Diego, City University of New York, Johns Hopkins University) present an experimental demonstration of light guiding in an atomically thick tungsten disulfide membrane patterned as a photonic crystal structure. In this scheme, two-dimensional tungsten disulfide excitonic photoluminescence couples into quasi-guided photonic crystal modes known as resonant-type Wood’s anomalies. These modes propagate via total internal reflection with only a small portion of the light diffracted to the far field. Such light guiding at the ultimate limit provides more possibilities to miniaturize optoelectronic devices and to test fundamental […]