Phys.org August 27, 2021 Despite considerable progress in microscale and nanoscale lasers the coherence length remains very limited. Researchers in Denmark explored the physics and applications of a new class of photonic devices using Fano interference which operates in bound-state-in the-continuum, induced by the Fano resonance. They showed experimentally as well as theoretically that the characteristics of such a bound-state-in-the-continuum can be harnessed to improve the coherence of the laser. They developed an advanced nanotechnology platform, called Buried Heterostructure Technology which allows realizing small, nanometer-sized regions of active material, where the light generation takes place, while the remaining laser structure […]
Tag Archives: Photonics
Quantum emitters: Beyond crystal clear to single-photon pure
Phys.org September 2, 2021 Quantum dots often suffer from adjacent unwanted emitters, which contribute to the background noise of the QD emission and fundamentally limit the single-photon purity. Researchers in South Korea developed a technique that can isolate the desired quality emitter by reducing the noise surrounding the target with what they have dubbed a ‘nanoscale focus pinspot. The technique is a structurally nondestructive technique under an extremely low dose ion beam and is generally applicable for various platforms to improve their single-photon purity while retaining the integrated photonic structures. Using this technique they focused the ion beam on a […]
Millimeter wave photonics with terahertz semiconductor lasers
Phys.org March 15, 2021 To accommodate the volume of wireless telecommunication traffic corresponding increases in bandwidth is necessary. Millimeter wave generation using photonic techniques has so far been limited to the use of near-infrared lasers that are down-converted to the mm Wave region. Such methodologies do not currently benefit from a monolithic architecture and suffer from the quantum defect which can ultimately limit the conversion efficiency. An international team of researchers (Italy, France, UK) has demonstrated intracavity mmWave generation within terahertz quantum cascade lasers over the unprecedented range of 25 GHz to 500 GHz. Through ultrafast time resolved techniques, they highlighted the […]
International study reveals exceptional property of next generation optical fibers
EurekAlert February 15, 2021 The elastic backscattering of light in optical fiber is a fundamental phenomenon that sets the ultimate performance of several fiber systems such as gyroscopes and bidirectional transfer links. Until now, efforts to reduce the backscattering coefficient have yielded limited results. An international team of researchers (Canada, UK) measured backscattering from a low-loss antiresonant hollow-core fiber and showed that it is more than 40 dB below reported values in silica-core fiber and hollow-core photonic bandgap fiber. The record-low level of −118dB/m measured with their optical frequency-domain reflectometer is in good agreement with simulations in which they assumed […]
‘Multiplying’ light could be key to ultra-powerful optical computers
EurekAlert February 8, 2021 An international team of researchers (Russia, UK) found that optical systems can combine light by multiplying the wave functions describing the light waves instead of adding them and may represent a different type of connections between the light waves. If the coupling and light intensity is right, the light multiplies, affecting the phases of the individual pulses, giving away the answer to the problem. They found that there is no need to project the continuous light phases onto ‘0’ and ‘1’ states necessary for solving problems in binary variables. Instead, the system tends to bring about […]
Silicon waveguides move us closer to faster, light-based logic circuits
Phys.org February 8, 2021 Wiring up the transistors of an optical circuit with silicon waveguides is an important requirement to make compact, highly integrated chips. However, silicon is a strong absorber of visible light. To circumvent the absorption issue researchers in Switzerland used high contrast grating consisting of nanometer sized “posts” lined up in such a way that light passing through the posts interferes destructively with light passing between posts making sure that no light can “leak” through the grating. Most of the light gets reflected inside the waveguide. They showed that there was a loss of only 13 percent […]
Researchers create novel photonic chip
Phys.org February 2, 2021 Photonic Digital‐to‐analog converters (DAC) enable a seamless signal conversion with respect to both energy efficiency and short signal delay. Using a silicon photonic chip platform, a team of researchers (Washington University, UCLA) has developed a coherent parallel photonic DAC concept along with a 4‐bit prototype capable of performing as DAC without optic–electric–optic domain crossing. This guarantees a linear intensity weighting among bits when operating at high sampling rates (50 GHz), featuring an exceptional sampling efficiency (> 100 GS −1 ) and small footprint (≈1 mm2) in an 8‐bit implementation. The photonic DAC enables seamless interfaces of next‐generation data processing hardware […]
Molecules convert visible light into ultraviolet light with record efficiency
EurekAlert December 4, 2020 To directly convert visible light with wavelengths longer than 400 nm into higher-energy ultraviolet light researchers in Japan focused on triplet-triplet annihilation where triplets are formed on molecules following absorption of visible light. These “donor” molecules then give their triplets to “acceptor” molecules that can combine two triplets to create a single, higher-energy state that is released as ultraviolet light. They developed an acceptor molecule TIPS-naphthalene that has a high triplet-triplet-annihilation efficiency and a low enough triplet energy to easily accept triplets from a molecule called Ir(C6)2(acac). The combination of TIPS-naphthalene and Ir(C6)2(acac) successfully achieved the […]
Infrared light antenna powers molecular motor
EurekAlert October 28, 2020 Light-controlled molecular motors can be used to create functional materials, to provide autonomous motion or in systems that can respond on command. An international team of researchers (the Netherlands, Switzerland, Germany) designed a rotary motor that is efficiently powered by near-infrared light, through adding an antenna to the motor molecule. Through a covalent bond, the motor molecule was linked to an ‘antenna’, which can absorb two near-infrared photons. The resulting excitation of the antenna is then passed on to the motor part of the molecule. For the system to work, the energy levels of the antenna […]
Well-formed disorder for versatile light technologies
Nanowerk October 13, 2020 In nonlinear crystals, two photons of a particular frequency can be turned into one photon having twice that frequency if they are phase matched. This often severely limits practical applications. Researchers in Switzerland combined resonances and disorder by implementing random quasi-phase-matching in Mie resonant spheres of a few micrometres realized by the bottom-up assembly of barium titanate nanocrystals. The measured second-harmonic generation reveals a combination of broadband and resonant wave mixing, in which Mie resonances drive and enhance the second-harmonic generation, while the disorder keeps the phase-matching conditions relaxed. The nanocrystal assemblies provide new opportunities for […]