Eurekalert April 20, 2018 An international team of researchers (Finland, Germany) has shown that carefully structured light and matching arrangements of metal nanostructures (plasmonic oligomers) can be combined to alter the properties of the generated light at the nanometer scale. They designed and fabricated assemblies of gold nanorods with well-defined dimensions and orientations such that their overall size matches the size of a focused laser beam, i.e., about 1 micron. The results show in general how important it is to tailor the incident optical beam to couple light efficiently into complex nanostructures. Their results will be useful in the design […]
Category Archives: Photonics
The future of photonics using quantum dots
Nanowerk March 27, 2018 Quantum dot lasers, amplifiers, modulators, and photodetectors epitaxially grown on Si are showing promise for achieving low-cost, scalable integration with silicon photonics. Researchers at UC Santa Barbara made III-V quantum-dot lasers using molecular beam epitaxy. They can run on less power, operate at higher temperatures and scaled down to smaller sizes. They are now testing lasers that can operate at 60 to 80 degrees Celsius, the more typical temperature range of a data center or supercomputer. Replacing the electronic components that connect devices with photonic components could cut energy use by 20 to 75 percent…read more. […]
Atomically thin light-emitting device opens the possibility for ‘invisible’ displays
Science Daily March 26, 2018 Transition-metal dichalcogenide monolayers have naturally terminated surfaces and can exhibit a near-unity photoluminescence quantum yield in the presence of suitable defect passivation. An international team of researchers (USA – UC Berkeley, Lawrence Berkeley National Laboratory, Saudi Arabia) fabricated a monolayer seven-segment display and achieved the first transparent and bright millimeter-scale light-emitting monolayer semiconductor device. Electroluminescence is obtained by applying an AC voltage between the gate and the semiconductor. The electroluminescence intensity is weakly dependent on the Schottky barrier height or polarity of the contact. According to the researchers the device is a proof-of-concept, and much […]
Depth-sensing imaging system can peer through fog (w/video )
MIT News March 20, 2018 Using a single photon avalanche diode camera that time-tags individual detected photons, researchers at MIT have demonstrated a technique that recovers reflectance and depth of a scene obstructed by dense, dynamic, and heterogeneous fog. They developed a probabilistic computational framework to estimate the fog properties from the measurement itself, and distinguished between background photons reflected from the fog and signal photons reflected from the target. In laboratory experiments the system was able to resolve images of objects and gauge their depth at a range of 57 centimeters. The system calculates a different gamma distribution for […]
New ultrafast measurement technique shows how lasers start from chaos
Physorg March 9, 2018 By measuring the laser temporal intensity with sub-picosecond resolution, as well as its optical spectrum with sub-nanometer resolution simultaneously, an international team of researchers (Finland, France) retrieved the complete characteristics of the underlying electromagnetic field. The results provide a very convenient laboratory example of a dissipative soliton system which is a central concept in nonlinear science and relevant to studies in other fields, such as biology, medicine and possibly even social sciences… read more. TECHNICAL ARTICLE
Controlled coupling of light and matter
Physorg March 6, 2018 To achieve the reabsorption of a photon at room temperature, an international team of researchers (Germany, UK) used a plasmonic nanoresonator, in the form of an extremely narrow slit in a thin gold layer. They controlled the coupling between the resonator and the quantum emitter by implementing a method that allows them to continuously change the coupling and, to switch it on and off in a precise manner. They hope to be able to controllably manipulate the coupling of the quantum dot and the resonator not only by changing their distance, but also through external stimuli—possibly […]
Faster data transfer through plasmons
Nanowerk February 22, 2018 Surface plasmon polaritons (SPPs) function like photonic elements, carrying information at high speeds. Researchers in Singapore designed transducers comprising aluminum and gold electrodes, separated by a two nanometer-thick layer of aluminum oxide that acts as an insulating ‘quantum tunneling’ barrier. Electrons that make the quantum leap across this gap will either generate or detect SPPs. By joining two transducers with a plasmonic waveguide, so that one acted as a source and another as detector they observed about 1 in 7 of the tunneling electrons coupling to a SPP. The invention has potential applications in three-dimensional integrated […]
New hole-punched crystal clears a path for quantum light
Science Daily February 15, 2018 Researchers at the University of Maryland created a photonic chip that both generates single photons and steers them around. In the new chip, they etched out thousands of triangular holes in an array that resembled a bee’s honeycomb. Along the center of the device they shifted the spacing of the holes, which opens a different kind of travel lane for the light. The team tested the capabilities of the chip by first changing a quantum emitter from its lowest energy state to one of its two higher energy states. When they used photons from the […]
Physicists create new form of light
MIT News February 15, 2018 A team of researchers in the US (MIT, Harvard University, Princeton University, NITS, University of Chicago) has observed groups of three photons interacting and, in effect, sticking together to form a completely new kind of photonic matter. In controlled experiments, the researchers found that when they shone a very weak laser beam through a dense cloud of ultracold rubidium atoms, rather than exiting the cloud as single, randomly spaced photons, the photons bound together in pairs or triplets, suggesting some kind of interaction — in this case, attraction — taking place among them. According to […]
Researchers demonstrate graphene as a source of high-speed light pulses
Phys org February 5, 2018 An international team of researchers (South Korea, USA – Columbia University, MIT, Cornell University, Stanford University, SLAC, University of Minnesota, Spain, Japan) encapsulated graphene in hexagonal boron nitride which allows the graphene to reach temperatures that are high enough to emit bright light in the visible and near infrared range, with good stability (estimated device lifetimes of at least 4 years), and fast cooling. As a result, the device generates ultrafast light pulses with a duration as short as 90 picoseconds and a modulation rate that is several orders of magnitude faster than conventional thermal […]