Phys.org May 26, 2023 The most common strategy to apply bound states in the continuum (BICs) in a metasurface is by breaking symmetry of resonators in the uniform array that leaks the otherwise uncoupled mode to free space and exhibits an inverse quadratic relationship between quality factor (Q) and asymmetry. Researchers in China have proposed a scheme to further reduce scattering losses and improve the robustness of symmetry protected BICs by decreasing the radiation density with a hybrid BIC lattice. They observed a significant increase of radiative Q in the hybrid lattice compared to the uniform lattice. In the hybrid […]
Tag Archives: Photonics
Closing in on next-generation atom-thick photonic devices
Phys.org March 13, 2023 The materials used to make photodetectors often hamper efforts to make improved broadband nanoscale photodetectors. To overcome these difficuties a team of researchers in the US (San Francisco State University, Stanford University) developed a photodetector that has improved sensitivity in the ultraviolet to near-infrared light range. High photoresponsivity at wavelength 400 nm measured at 77 K, which translates into an external quantum efficiency. The 90% rise time of the devices at 77 K is 0.1 ms, suggesting they can operate at the speed of ≈10 kHz. High-performance broadband photodetector with spectral coverage ranging from 380 to 1000 nm was demonstrated. According to […]
Unique modulator could change mid-infrared photonic systems for the better
Phys.org December 12, 2022 Optical modulators are crucial photonic circuits that enable signal switching and routing, data encoding, phase-sensitive detection, and spectroscopic interrogation. Researchers in China have developed a new MIR all-optical modulator based on an acetylene-filled hollow-core fiber. Optical absorption of the control beam promotes the gas molecules to a higher energy level, which induces localized heating through non-radiative relaxation and modulates the refractive index of the gas material and hence the accumulated phase of the signal beam propagating through the hollow-core fiber. By modulating the intensity of the control beam, they modulated the phase of the signal beam. […]
Using lasers to bond semiconductor electronics components
Phys.org December 5, 2022 Important physical limitations have prevented applying laser micro-welding to silicon (Si) and other technology-essential semiconductors. High intensities are required for internal glass modification. However, they result in strong propagation nonlinearities which defocus and delocalize intense infrared radiation. To overcome this, researchers in France created defects inside silicon that later serve as weak points to produce clean-edge cuts. The defects acted as strong bonding points. After setting up the right conditions to circumvent the effects, they successfully made the first experimental demonstration of silicon-silicon laser welding. After an optimization process, they extended the technique to gallium arsenide […]
Researchers unlock light-matter interactions on sub-nanometer scales, leading to ‘picophotonics’
Phys.org November 16, 2022 The concept of photonic frequency-momentum (ω-q) dispersion has been extensively studied in artificial dielectric structures such as photonic crystals and metamaterials, but not in in natural materials at the atomistic level. Researchers at Purdue University have developed a Maxwell Hamiltonian theory of matter combined with the quantum theory of atomistic polarization to obtain the electrodynamic dispersion of natural materials interacting with the photon field. They applied this theory to silicon and discovered the existence of anomalous atomistic waves. These waves occur in the spectral region where propagating waves are conventionally forbidden in a macroscopic theory. According […]
Researchers find the missing photonic link to enable an all-silicon quantum internet
Phys.org July 13, 2022 The global quantum internet will require long-lived, telecommunications-band photon–matter interfaces manufactured at scale. Preliminary quantum networks based on photon–matter interfaces that meet a subset of these demands are encouraging efforts to identify new high-performance alternatives. Silicon is an ideal host for commercial-scale solid-state quantum technologies. It is already an advanced platform within the global integrated photonics and microelectronics industries, as well as host to record-setting long-lived spin qubits. Despite the overwhelming potential of the silicon quantum platform, the optical detection of individually addressable photon–spin interfaces in silicon have remained elusive. In their work researchers in Canada […]
Direct generation of complex structured light
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 […]
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 […]