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 […]
Tag Archives: Optics
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 […]
Scientists reduced the weight of optics for satellite observation by 100 times
Eurekalert August 8, 2018 Researchers in Russia have created an optical element for reconstructing images taken with diffractive optics on a satellite. It weighs only 5 grams and replaces a complex and massive system of lenses and mirrors similar to the one that is used in telephoto lenses with a focal length of 300 mm and a weight of 500 grams. They proposed to compensate for distortions with the use of digital processing. The computational reconstruction developed by them includes colour correction of the image and elimination of chromatic blurring using convolutional neural networks (CNN). The compact system is particularly […]
Speed of light drops to zero at ‘exceptional points’
Phys org January 31, 2018 An international team of researchers (Israel, Brazil) has theoretically demonstrated a new way to bring light to a standstill at “exceptional points”. Exceptional points can be created in waveguides by varying the gain/loss parameters so that two light modes coalesce. The loss of light can be fixed by using waveguides with parity-time symmetry, as this symmetry ensures that the gain and loss are always balanced. To release the stopped light and accelerate it back up to normal speed, the gain/loss parameters can be reversed. Unlike most other methods that are used to stop light, the […]
Carbon nanotube as ultrafast emitter with narrow energy spread at optical frequency
Nanowerk January 2, 2018 An international team of researchers (China, Finland) used carbon nanotubes to achieve energy spreads as low as 0.25 eV to demonstrate field-driven ultrafast photo electron emission, in a system capable of much higher phase synchronization than its photon-driven counterpart. According to the researchers, their work will help reshape our understanding of strong field physics, and may very well light the way for entirely new types of electron emission systems. Read more. TECHNICAL ARTICLE