Nanowerk June 10, 2021 Metalenses promise to make imaging devices more compact. An international team of researchers (Canada, USA – University of Rochester) has addressed the space between the lenses which is crucial for image formation but takes up by far the most room in imaging systems, by introducing the idea of a spaceplate. They experimentally demonstrated that it is compatible with broadband light in the visible spectrum. They manipulated light based on the angle rather than the position of a light ray. Angle is a completely novel domain. They designed and experimentally demonstrated plates that compressed the space. Such […]
Tag Archives: Optics
Trapping light without back reflections
Phys.org January 4, 2021 Due to material imperfections, some amount of light is reflected backwards in microresonators which disturbs their function. To reduce the unwanted backscattering an international team of researchers (UK, Germany) used the principle of noise cancelling headphone and introduced out-of-phase light to cancel out optical interference. To generate the out-of-phase light, the researchers position a sharp metal tip close to the microresonator surface. The tip also causes light to scatter backwards. As the phase of the reflected light can be chosen by controlling the position of the tip, backscattered light’s phase can be set so it annihilates […]
Cartwheeling light reveals new optical phenomenon
Nanowerk June 29, 2020 While there are numerous forms of light polarization, only linear and circular polarizations, which have wave motion in a flat sheet or helix, respectively, are typically used. A team of researchers in the US (Rice University, UMass Dartmouth) utilized trochoidal polarizations with cartwheeling wave motion. They demonstrated that single gold nanorod dimers can discriminate between trochoidal fields rotating in opposite directions, which they named trochoidal dichroism. Trochoidal dichroism forms an additional classification of polarized light–matter interaction and could inspire the development of optical studies uniquely sensitive to molecules with cartwheeling charge motion, potentially relevant for probing […]
New water-based optical device revolutionizes the field of optics research
Phys.org November 20, 2019 Researchers in Japan have developed a light modulator using the Pockels effect of water in a nanometer-thick electric double layer on an electrode surface. The modulator comprises a transparent-oxide electrode on a glass substrate immersed in an aqueous electrolyte solution. When an optical beam is incident such that it is totally reflected at the electrode-water interface, the light is modulated at a specific wavelength with a near-100% modulation depth synchronized with the frequency of the applied AC voltage. Pockels effect has applications in optical engineering, optical communication, displays and electric sensors and the enhancement principle opens […]
Commemorating 30 years of optical vortices: A comprehensive review
Phys.org November 4, 2019 Researchers in China reviewed the 30-year development of the understanding and applications of these intriguing phenomena. The light waves of optical vortices (OVs) are twisted around their direction of travel, with a point of zero intensity at their center. They emphasized that the tunability of OVs includes not only the spectral and temporal tunability but also the OAM-, chirality-, topological-charge-, and singularity-distribution tunability. Prominent applications include sophisticated optical computing processes, novel microscopy and imaging techniques, the creation of ‘optical tweezers’ to trap particles of matter, and optical machining using light to pattern structures on the nanoscale…read […]
Light Seems to Pull Electrons Backward
American Physical Society Focus August 2, 2019 It is long assumed that light hitting a metal surface at an angle pushes on the free electrons, moving them forward. A team of researchers in the US (NIST, University of Maryland, Brown University) aimed an infrared laser toward the metal surface at a glancing angle and placed an electrode at the far end of the metal sample to detect any voltage created if the light drove the electrons along the metal, which would create an excess of negative charge at the far end. As they varied the angle, the team measured a […]
Shaping light with a smartlens
Nanowerk July 26, 2019 Liquid crystal spatial light modulators have been the tool of choice for high-resolution light shaping, but their implementation has proven to have limits in terms of performance, bulkiness and cost. An international team of researchers (Spain, France) has demonstrated a method of deterministic phase-front shaping using a planar thermo-optical module and designed microheaters to locally shape the refractive index distribution. When combined with a genetic algorithm optimization, this SmartLens can produce free-form optical wavefront modifications, generate complex functions based on either pure or combined Zernike polynomials, including lenses or aberration correctors of electrically tunable magnitude. This […]
Virtually energy-free superfast computing invented by scientists using light pulses
Science Daily May 15, 2019 An international team of researchers (Germany, USA- UC Santa Barbara, Russia, the Netherlands) utilized the efficient interaction mechanism of coupling between spins and terahertz electric field, which was discovered by the same team. They developed and fabricated a very small antenna on top of the magnet to concentrate and thereby enhance the electric field of light. This strongest local electric field was sufficient to navigate the magnetization of the magnet to its new orientation in just one trillionth of a second without increasing the temperature. Future storage devices would also exploit the excellent spatial definition […]
New device for manipulating and moving tiny objects with light
Science Daily November 27, 2018 An international team of researchers (South Africa, USA – MIT) has built and demonstrated a vector holographic optical trapping and tweezing system which allows micrometer sized particles, such as biological cells, to be captured and manipulated only with light. They showed how to create and control any pattern of light holographically, and then used this to form a new optical trapping and tweezing device. The device can work with both the traditional laser beams as well as more complex vector beams. The new device can be useful in single cell studies in biology and medicine, […]
‘Folded’ optical devices manipulate light in a new way
Phys.org October 31, 2018 In metasurface-based optical systems, most of the total volume inside the device is just free space through which light propagates between different elements. Free space makes it difficult to scale down the device. To overcome this limitation, a team of researchers in the US (Caltech, UMass Amherst) has introduced a technology called “folded metasurface optics,” which is a way of printing multiple types of metasurfaces onto either side of a substrate making the substrate itself a propagation space for the light. They demonstrated the technique by building a spectrometer. The folded metasystem design can be applied […]