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 […]
Category Archives: Photonics
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. […]
If you want to catch more light, twist it
Nanowerk January 31, 2020 The bulk photovoltaic effect is a way to convert light into electrical current. An international team of researchers (USA – Boston College, UCLA, Germany, Switzerland) developed microscopic devices based on the Weyl semimetal tantalum arsenide. They had larger bulk photovoltaic effect than seen before. The devices they developed absorbed mid-infrared light, an important wavelength for devices that conduct chemical and thermal imaging as well as waste heat recovery. The observed magnitude and wavelength range of the shift current advances our fundamental understanding of the effects of topology in materials. It also demonstrates the utility of Weyl […]
Converting absorbed photons into twice as many excitons
Science Daily September 24, 2019 An international team of researchers (Japan, Finland) found that when light was exposed to the surface of a tetracene alkanethiol-modified gold nanocluster, they were able to convert singlet oxygen at a highly efficient conversion rate of 160%, far exceeding 100% conversion, in comparison to the number of absorbed photons. An increase in lifetime of about 10,000 times was achieved by greatly suppressing the rapid loss of excitation energy on the metal surface. These findings are expected to contribute to areas such as solar energy conversion, electronics, life sciences, and medical care in the future…read more. […]