Phys.org September 26, 2023 UV and visible photonics enable applications ranging from spectroscopic sensing to communication and quantum information processing. Photonics structures in these wavelength regimes tend to experience higher loss than their IR counterpart. Particularly in the near-UV band, on-chip optical microresonators have not yet achieved a quality factor beyond 1 million. A team of researchers in the US (Yale University, industry) developed ultra-low-loss photonic waveguides and resonators patterned from alumina thin films prepared by a highly scalable atomic layer deposition process. They demonstrated ultra-high Q factor of 1.5×106 at 390 nm, a record value at UV bands, and 1.9×106 […]
Tag Archives: Waveguides
Shrinking light: Waveguiding scheme enables highly confined subnanometer optical fields
Phys.org July 17, 2023 Researchers in China developed an optical waveguide scheme to generate a sub-nanometer-confined optical field in a nano slit waveguiding mode in a coupled nanowire pair (CNP). They showed that, when a conventional waveguide mode with a proper polarization was evanescently coupled into a properly designed CNP with a central nano slit, it could be channeled into a high-purity nano slit mode within a waveguiding length <10 μm. The CNP could be either freestanding or on-chip by using a tapered fiber or planar waveguide for input-coupling, with a coupling efficiency up to 95%. Within the slit region, […]
On-chip photodetection: Two-dimensional material heterojunctions
Phys.org May 13, 2022 Chip-integrated two-dimensional material photodetectors implemented with the configuration of metal-semiconductor-metal suffer from high dark currents and low responsivities at high operation speed. An international team of researchers (China, Belgium, Spain, Finland) has developed a van der Waals PN heterojunction photodetector, composed of p-type black phosphorous and n-type molybdenum telluride, integrated on a silicon nitride waveguide. The built-in electric field of the PN heterojunction significantly suppresses the dark current and improves the responsivity. The dark current is lower than 7 nA, which is more than two orders of magnitude lower than those reported in other waveguide-integrated black phosphorus […]
‘Shadow waveguide’ casts complex acoustic patterns to control particles
Phys.org August 18, 2021 Despite all its potential, the acoustic tweezer technology makes it difficult to manipulate particles independently of one another or through complex patterns. To overcome the limitation of the acoustic tweezer a team of researchers in the US (Duke University, Rowan University) has demonstrated spatially complex particle trapping and manipulation inside a boundary-free chamber using a single pair of sources and an engineered structure outside the chamber that they call a shadow waveguide. The shadow waveguide creates a tightly confined, spatially complex acoustic field inside the chamber without requiring any interior structure that would interfere with net […]
Scientists Have Created a New Bendy And Flexible Form of Ice
Science Alert July 9, 2021 An international team of researchers (USA – UC Berkeley, China) used tungsten needle in a ultracold chamber around -50 deg C into which water vapor was released and applied an electric field. Water molecules were attracted to the tip of the needle, where they crystallized, forming a microfiber with a maximum width of around 10 micrometers. When the temperature was lowered to between minus 70 and minus150 degrees Celsius they were able to bend. At minus 150 degrees Celsius, the microfiber 4.4 micrometers across was able to bend into a nearly circular shape, with a […]