Nanowerk August 7, 2023 Researchers in Israel developed a spin-optical monolayer laser by incorporating a WS2 monolayer into a heterostructure microcavity supporting high-Q photonic spin-valley resonances. They generated the spin-valley modes from a photonic Rashba-type spin splitting of a bound state in the continuum, which gave rise to opposite spin-polarized ±K valleys due to emergent photonic spin–orbit interaction under inversion symmetry breaking. The laser showed intrinsic spin polarizations, high spatial and temporal coherence, and inherent symmetry-enabled robustness features, enabling valley coherence in the WS2 monolayer upon arbitrary pump polarizations at room temperature. According to the researchers their work on monolayer-integrated […]
Tag Archives: Optoelectronic devices
Unipolar quantum optoelectronic devices: Higher speeds in free-space optical communications in the midinfrared band
Phys.org November 2, 2022 A recently demonstrated proof-of-concept of high-speed transmission taking advantage of intersubband devices was limited by the short-distance optical path (up to 1 m). An international team of researchers (France, USA -University of Central Florida, University of New Mexico) used an uncooled quantum cascade detector and a nitrogen-cooled quantum well-infrared photodetector to study the possibility of building a long-range link using unipolar quantum optoelectronics. They evaluated the maximum data rate of their link in a back-to-back configuration before adding a Herriott cell to increase the length of the light path up to 31m. By using pulse shaping, […]
Small molecules, giant (surface) potential
Phys.org August 26, 2022 The performance of organic optoelectronic and energy-harvesting devices is largely determined by the molecular orientation and resultant permanent dipole moment, yet this property is difficult to control during film preparation. Researchers in Japan have demonstrated the active control of dipole direction in organic glassy films by physical vapour deposition. It was obtained by utilizing the small surface free energy of a trifluoromethyl unit and intramolecular permanent dipole moment induced by functional groups. According to the researchers their work could pave a way toward the formation of spontaneously polarized organic glassy films, leading to improvement in the […]
Atomically-smooth gold crystals help to compress light for nanophotonic applications
Phys.org July 13, 2022 An international team of researchers (South Korea, Denmark, Switzerland, Japan, USA – University of Minnesota) used a highly sensitive scanning near-field optical microscope (SNOM) to directly measure the optical fields of the hyperbolic image phonon-polaritons (HIP) propagating in a 63 nm-thick slab of hexagonal boron nitride (h-BN) on a monocrystalline gold substrate, showing the mid-infrared light waves in dielectric crystal compressed by a hundred times. They showed that the phonon-polaritons in van der Waals crystals can be significantly more compressed without sacrificing their lifetime. Practically zero surface scattering and extremely small ohmic loss in gold at […]
Graphene-hBN breakthrough to spur new LEDs, quantum computing
Science Daily April 14, 2022 Graphene-hBN structures can power LEDs that generate deep-UV light, which is impossible in today’s LEDs. Previous efforts to get ordered rows of hBN atoms that align with the graphene underneath were not successful. A team of researchers in the US (University of Michigan, Ohio State University, Yale University) discovered that neat rows of hBN atoms are more stable at high temperature than the undesirable jagged formations. They used a terraced graphene substrate and heated it to around 1600 degrees Celsius before spraying on individual boron and active nitrogen atoms resulting in neatly ordered seams of […]
New p-type, near-infrared transparent conducting thin films with better performance
Phys.org January 19, 2022 The low conductivity of previous CuMO2 films obstructs the development of delafossite-based electronics. Researchers in China designed and fabricated a new p-type 4d transition metal Rh-based CuRhO2 film by a facile solution method. It has room-temperature conductivity as high as 735 S cm−1 which was achieved by substituting 10%Mg in Rh sites. The acceptor-doped CuRhO2 films exhibited high near-infrared transmittance of 85–60% with low room-temperature sheet resistance of 4.28–0.18 kΩ sq−1. The electronic structure, electrical transport mechanism, and intra-band excitation feature for the CuRhO2 film are unveiled. According to the researchers theoretical and experimental results contribute […]
Liquid crystals for fast switching devices
Phys.org December 6, 2021 In some liquid crystals the molecules self-assemble into helical structures which are characterized by pitch. Pitch determines how quickly they react to an applied electric field. An international team of researchers (Germany, Czech Republic, Russia) investigated a liquid crystalline cholesteric compound called EZL10/10 which had only one chiral center and it was only104 nanometres. Further analysis showed that in this material the cholesteric spirals form domains with characteristic lengths of about five pitches. According to the researchers the short pitch makes the material unique and promising for optoelectronic devices with very fast switching times, and the […]
A perovskite-based diode capable of both light emission and detection
Phys.org April 10, 2020 An international team of researchers (Sweden, China, Italy, Switzerland) has developed an efficient solution-processed perovskite diode that can work in both emission and detection modes. The device can be switched between modes by changing the bias direction, and it exhibits light emission with an external quantum efficiency of over 21% and a light detection limit on a subpicowatt scale. The operation speed for both functions can reach tens of megahertz. The diodes exhibit a high specific detectivity at its peak emission (~804 nm), which allows an optical signal exchange between two identical diodes. To illustrate the potential […]