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, […]
Category Archives: Photonics
New device widens light beams by 400 times, broadening possibilities in science and technology
Phys.org November 28, 2018 A team of researchers in the US (NIST, University of Maryland, Texas Tech University) developed an extreme mode converter, which is a compact planar photonic structure that efficiently couples a 300 nm × 250 nm silicon nitride high-index single-mode waveguide to a well-collimated near surface-normal Gaussian beam. They separated the two-dimensional mode expansion into two sequential separately optimized stages, which create a fully expanded and well-collimated Gaussian slab mode before out-coupling it into free space. The design can be adapted for visible, telecommunication, or other wavelengths. The technique can be expanded to more arbitrary phase and intensity control of both […]
Changing color of light using a spatiotemporal boundary
Phys.org November 29, 2018 Effective temporal control of the medium is critical for frequency conversion. Researchers in South Korea designed a metasurface for the sudden merging of two distinct metallic meta-atoms into a single one upon ultrafast optical excitation. Sudden merging creates a spectrally designed temporal boundary on the metasurface by which the frequency conversion can be achieved and engineered. The technique provides a spatiotemporal boundary as a platform for freely designing and changing the spectral properties of the medium. Since frequency conversion can be observed even in weak light, this technique could be particularly useful in communication technology…read more. […]
Bending light around tight corners without backscattering losses
Phys.org November 19, 2018 An international team of researchers (USA – Duke University, SUNY Buffalo, Canada) combined the properties of a planar silicon photonic crystal and the concept of topological protection to design, fabricate and characterize an optical topological insulator. They showed that the transmittances are the same for light propagation along a straight topological interface and one with four sharp turns. The waveguide works very well even if there are minor defects in the photonic crystalline structure. It has a large operating bandwidth, compatible with modern semiconductor fabrication technologies, and works at wavelengths currently used in telecommunications…read more. TECHNICAL […]
Using a crystal to link visible light to infrared opens a window on infrared sensing
Phys. org November 1, 2018 Researchers in Singapore have developed a method that allows changes in the infrared beam to be analyzed via the visible beam, it provides more information than conventional spectroscopy. They fed laser light into a lithium niobate crystal that split some of the laser photons into two quantum-linked photons of lower energies through parametric down-conversion, one in the infrared, and one in the visible parts of the spectrum. When the original laser beam re-entered the crystal, it created a new pair of down-converted beams that interfered with the light created in the first pass. A sample […]
New half-light half-matter particles may hold the key to a computing revolution
Nanowerk October 11, 2018 An international team of researchers (UK, France) shows that by embedding the honeycomb metasurface between two reflecting mirrors and changing the distance between them, one can tune the fundamental properties of the Dirac polaritons in a simple, controllable and reversible way. They have shown the ability to slow down or even stop the Dirac particles, and modify their chirality which is impossible to do in graphene itself. The work opens the door for the development of photonic circuitry using these alternative particles and has implications for research in the field of Dirac particles…read more. Open Access […]
Bowtie-funnel combo best for conducting light; team found answer in simple equation
Phys.org August 24, 2018 An international team of researchers (USA – Vanderbilt University, IBM, France) developed a structure that’s part bowtie, part funnel that concentrates light powerfully and nearly indefinitely, as measured by a scanning near field optical microscope. Only 12 nanometers connect the points of the bowtie. What is special about their research is that the use of the bowtie shape concentrates the light so that a small amount of input light becomes highly amplified in a small region. We can potentially use that for low power manipulation of information on computer chips. Their approach opens the door to […]
A single photon detection system for the spectrum range up to 2300 nm
Arxiv July 11. 2018 An international team of researchers (Russia, Poland) has demonstrated niobium nitride based superconducting single-photon detectors are sensitive in the spectral range 457 nm – 2300 nm. The system performance was tested in a real-life experiment with correlated photons generated by means of spontaneous parametric down conversion, where one of photon was in the visible range and the other was in the infrared range. They measured a signal to noise ratio as high as 4×104 in their detection setting. A photon detection efficiency as high as 64 % at 1550 nm and 15 % at 2300 nm […]
Rotating resonator creates a one-way street for light
Physics World June 29, 2018 An international team of researchers (Israel, USA – University of Central Florida, University of Michigan, China, Japan) used a cylindrical, silica-glass resonator that is rotating on a turbine. An optical fibre is located 320 nm above the spinning resonator. Light travelling along the fibre interacting with the nearby resonator via the light’s short-range evanescent field perceives it to be less dense than light travelling in the opposite direction. This difference in apparent density results in different indices of refraction for light moving in opposite directions allowing the researchers to pass light of the same frequency […]
Cooling by laser beam
Science Daily June 8, 2018 Researchers in Italy explain that the laser pulse can, in some circumstances, populate high-energy states, which heat up, and simultaneously depopulate low energy ones, which thus cool down which is responsible for superconductivity. This selective cooling, shown rigorously in a very simplified theoretical model, could explain not only the experimental observations, but also open the way to new and potentially important research activities… read more. TECHNICAL ARTICLE