Phys.org March 18, 2022 An international team of researchers (China, USA – Arizona State University) generated structured transverse mode locking (TML) beams and second harmonic generation (SHG) beams by a sandwich-like microchip laser cavity that was passively Q-switched. They observed many rare SHG far-field beam patterns and their experiments showed good agreement with the simulations. It showed that parametric variation for the TML modes greatly changes the far-field beam patterns of the SHG beam. Generated SHG beam patterns vary with the propagation, and then they remain stable into the far field. The SHG beam patterns were observed to have more […]
Tag Archives: Photonics
Harnessing noise in optical computing for AI
Techxplore January 21, 2022 The inherent optoelectronic noises make the photonic systems error-prone in practice. To mitigate and harness noises in photonic computing systems a team of researchers in the US (University of Washington University, Duke University, University of Maryland) has designed and demonstrated a photonic generative network as a part of a generative adversarial network (GAN). The network is implemented with a photonic core consisting of an array of programable phase-change memory cells to perform four-element vector-vector dot multiplication. The GAN can generate a handwritten number (“7”) in experiments and full 10 digits in simulation. They developed an optical […]
Tiny lasers acting together as one: Topological vertical cavity laser arrays
Phys.org September 24, 2021 Vertical-Cavity Surface-Emitting Lasers (VCSEL) device has miniscule size of only a few microns, which sets a stringent limit on the output power it can generate. An international team of researchers (Israel, Germany) utilized the concepts of topological photonics with VCSELs that emit light vertically, while the topological process responsible for the mutual coherence and locking of the VCSELs occurs in the plane of the chip. It resulted in a powerful but very compact and efficient laser, not limited by a number of VCSEL emitters, and undisturbed by defects or altering temperatures. The topological principle of this […]
Novel physics gives rise to the highest coherence for microscopic lasers
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 […]
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 […]