Phys.org October 15, 2020 Unusual structural colors are demonstrated in thin‐film coatings due to a combination of optical interference and light scattering effects. These vivid colors are concealed under ambient illumination but can be observed when light is reflected from the film surface. An international team of researchers (Australia, China, Germany) explored the origin of the effect computationally and showed that, in thin‐films of lossless dielectrics coated on near‐perfect conductors, incident electromagnetic waves form standing waves. Electric field intensities at the thin film interfaces are maximized for wavelengths that fulfil destructive interference conditions, while nanoscale roughness can enhance scattering at […]
Category Archives: Photonics
Intelligent nanomaterials for photonics
Science Daily October 7, 2020 2D materials – combined with optical fibers – can enable novel applications in the areas of sensors, non-linear optics, and quantum technologies. An international team of researchers (Germany, Australia) studied the chemical vapor deposition of monolayer MoS2 and WS2 crystals on the core of microstructured exposed‐core optical fibers and their interaction with the fibers’ guided modes. Two distinct application possibilities of 2D‐functionalized waveguides to exemplify their potential are demonstrated. First, the excitonic 2D material photoluminescence is simultaneously excited and collected with the fiber modes. Then it is shown that third‐harmonic generation is modified by the highly […]
Physicists create turnstile for photons
Phys.org September 22, 2020 If the quantum emitter is excited with laser light and fluoresces, it will always emit exactly one photon with each quantum leap. For this type of source, it is then still a challenge to efficiently “feed” the emitted photons into a glass fiber to send as many of them as possible to the receiver. An international team of researchers (Austria, Germany, Denmark) generated strongly correlated photon states using only weak coupling and taking advantage of dissipation. An ensemble of non-interacting waveguide-coupled atoms induces correlations between simultaneously arriving photons through collectively enhanced nonlinear interactions. These correlated photons […]
Physicists ‘trick’ photons into behaving like electrons using a ‘synthetic’ magnetic field
Nanowerk September 14, 2020 Researchers in the UK have shown that it is possible to create artificial magnetic fields for light by distorting honeycomb metasurfaces that are engineered to have structure on a scale much smaller than the wavelength of light. They embedded the metasurface in photonic cavity and showed that it is possible to tune the artificial magnetic field by changing only the width of the photonic cavity, thereby removing the need to modify the distortion in the metasurface. Using this mechanism it is possible to bend the trajectory of the polaritons using a tunable Lorentz-like force and also […]
Engineers manipulate color on the nanoscale, making it disappear
Nanowerk August 13, 2020 An international team of researchers (USA – University of Pennsylvania, Industry, UCLA, Singapore) demonstrated that nanostructured, multilayer transition metal dichalcogenides (TMDCs) by themselves provide an ideal platform for excitation and control of excitonic modes, paving the way to exciton-photonics. Inherently strong TMDC exciton absorption resonances may be completely suppressed due to excitation of hybrid light-matter states and their interference. The work paves the way to the next generation of integrated exciton optoelectronic nano-devices and applications in light generation, computing, and sensing…read more. Open Access TECHNICAL ARTICLE
Photonic metasurfaces provide a new playground for twistronics
Phys.org April 27, 2020 Hyperbolic metasurfaces (HMTSs) are known to support confined surface waves collimated toward specific directions determined by the metasurface dispersion. By rotating two evanescently coupled HMTSs with respect to one another, an international team of researchers (USA – University of New York, UT Austin, Singapore) unveil rich dispersion engineering, topological transitions at magic angles, broadband field canalization, and plasmon spin-Hall phenomena. These findings open remarkable opportunities to advance metasurface optics, enriching it with moiré physics and twistronic concepts…read more. TECHNICAL ARRTICLE
First bufferless lasers grown directly on silicon wafers in Si-photonics
Nanowerk March 4, 2020 In conventional approaches of integrating III-V lasers on Si thick III-V buffers up to a few micrometers are used to reduce the defect densities, which posses huge challenges for efficient light interfacing between the epitaxial III-V lasers and the Si-based waveguides. Based on numerical simulations an international team of researchers (China, Hong Kong) designed and fabricated a novel growth scheme to eliminate the requirement of thick III-V buffers and thus promoted efficient light coupling into the Si-waveguides. They demonstrated the 1.5 µm III-V lasers directly grown on the industry-standard 220 nm SOI wafers using metal organic […]
Researchers create new state of light
Phys.org February 25, 2020 Light rotates around a longitudinal axis parallel to the direction light travels. An international team of researchers (China, USA – University of Dayton) has demonstrated a three-dimensional wave packet that is a spatiotemporal (ST) optical vortex with a controllable purely transverse orbital angular momentum (OAM). The magnitude of the transverse OAM carried by the ST vortex is scalable to a larger value by simple adjustments. Since the ST vortex carries a controllable OAM uniquely in the transverse dimension, it has strong potential for novel applications that may not be possible otherwise. The scheme reported here can […]
Using light to put a twist on electrons
Science Daily February 26, 2020 Chirality occurs not in the structure of the molecules themselves, but in a kind of patterning in the density of electrons within the material. An international team of researchers (USA – MIT, Carnegie Mellon, Northeastern University, Cornell University, Drexel University, Taiwan, Singapore, Japan) found that while titanium diselenide at room temperature has no chirality to it, as its temperature decreases it reaches a critical point where the balance of right-handed and left-handed electronic configurations gets thrown off and one type begins to dominate. They found that this effect could be controlled and enhanced by shining […]
What if we could teach photons to behave like electrons?
Phys.org February 19, 2020 An international team of researchers (USA – Stanford University, China) tricked the photons—which are intrinsically non-magnetic—into behaving like charged electrons by sending the photons through carefully designed mazes in a way that caused the light particles to behave as if they were being acted upon by what the scientists called a “synthetic” or “artificial” magnetic field. They designed structures that created magnetic forces capable of pushing photons in predictable and useful ways. To bring photons into the proximities required to create these magnetic effects, the researchers used lasers, fiber optic cables and other off-the-shelf scientific equipment. […]