Phys.org November 1, 2024 The guiding and transport of energy, for example, of electromagnetic waves, underpins many modern technologies, ranging from long-distance optical fibre telecommunications to on-chip optical processors. It requires localizing the waves or particles in the confinement region, such as total internal reflection at a boundary. An international team of researchers (UK, USA – University of Arizona) introduced a waveguiding mechanism that relies on a different origin for the exponential confinement and that arises owing to the physics of diffusion. They demonstrated this concept using light and showed that the photon density could propagate as a guided mode […]
Tag Archives: Photonic devices
Moving from the visible to the infrared: Developing high quality nanocrystals
Phys.org July 9, 2024 Colloidal semiconductor nanocrystals based on CdSe have been precisely optimized for photonic applications in the visible spectrum. A team of researchers in the US (University of Illinois Urbana-Champaign, Carle Illinois College of Medicine, Urbana) developed homogeneous nanocrystals with tunable bandgaps in the infrared spectrum based on HgSe and HgxCd1−xSe alloys derived from CdSe precursors. They found that Ag+ catalyses cation interdiffusion reduced the CdSe–HgSe alloying temperature from 250 °C to 80 °C. Together with ligands that modulated surface cation exchange rates, interdiffusion-enhanced Hg2+ exchange of diverse CdSe nanocrystals proceeded homogeneously and completely. The products retained the size, shape […]
Eyes on the impossible: First near-field, subwavelength thermal radiation measurement
Phys.org March 18, 2024 Researchers at Carnegie Mellon University designed a thermal photonic nanodevice for the first measurement of near-field energy transport between two coplanar subwavelength structures over temperature bias up to ∼190 K. Their experimental results demonstrated a 20-fold enhancement in energy transfer beyond blackbody radiation. In contrast with the well-established near-field interactions between two semi-infinite bodies, the subwavelength confinements in nanodevices led to increased polariton scattering and reduction of supporting photonic modes and, therefore, a lower energy flow at a given separation. According to the researchers their work opens new designs for nanodevices, particularly for coplanar near-field energy […]
Arrays of quantum rods could enhance TVs or virtual reality devices
MIT News August 11, 2023 Scalable fabrication of two-dimensional (2D) arrays of quantum dots (QDs) and quantum rods (QRs) with nanoscale precision is required for numerous device applications. However, self-assembly–based fabrication of such arrays using DNA origami typically suffers from low yield due to inefficient QD and QR DNA functionalization and it is challenging to organize solution-assembled DNA origami arrays on 2D device substrates while maintaining their structural fidelity. Researchers at MIT reduced manufacturing time from a few days to a few minutes by preparing high-density DNA-conjugated QDs/QRs from organic solution using a dehydration and rehydration process. They used a […]
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 […]