Nanowerk August 7, 2023 Researchers in Israel developed a spin-optical monolayer laser by incorporating a WS2 monolayer into a heterostructure microcavity supporting high-Q photonic spin-valley resonances. They generated the spin-valley modes from a photonic Rashba-type spin splitting of a bound state in the continuum, which gave rise to opposite spin-polarized ±K valleys due to emergent photonic spin–orbit interaction under inversion symmetry breaking. The laser showed intrinsic spin polarizations, high spatial and temporal coherence, and inherent symmetry-enabled robustness features, enabling valley coherence in the WS2 monolayer upon arbitrary pump polarizations at room temperature. According to the researchers their work on monolayer-integrated […]
Category Archives: Lasers
Scientists develop a broadband quantum-dot frequency-modulated comb laser
Phys.org July 27, 2023 The formation of a broadband optical frequency comb relies on careful engineering of the group velocity dispersion (GVD) of the waveguide, which is challenging for platforms where the GVD is mainly determined by the material. An international team of researchers (USA – UC Santa Barbara, Egypt) has generated a 60 GHz quantum-dot (QD) mode-locked laser in which both the amplitude-modulated (AM) and the frequency-modulated (FM) comb could be generated independently. The high four-wave-modulated (FWM) efficiency of –5 dB allowed the QD laser to generate FM comb efficiently. They demonstrated that the Kerr nonlinearity could be practically engineered to […]
Researchers develop new electrically pumped edge-emitting laser chip with unprecedented performance
Phys.org June 27, 2023 Large-area lasers that emit high output powers have lower beam quality due to the introduction of higher-order modes. An international team of researchers (Turkey, USA – Michigan Technological University) has demonstrated a new type of electrically pumped, large-area edge-emitting lasers that exhibited a high-power emission and a high-quality beam. These characteristics were enabled by establishing a quasi PT-symmetry between the second-order mode of a large area two-mode laser cavity and a single-mode auxiliary partner cavity. This in turn enlarges the effective volume of the higher-order modes. As a result, a selective pump applied via current injection […]
Researchers develop ultraefficient white light laser on a chip
Phys.org March 13, 2023 Supercontinuum lasers are able to produce a continuous spectrum of color and can therefore appear white. To generate the wide bandwidth of colors, supercontinuum lasers have a high peak power consumption, they are enormous and have to be stabilized in a laboratory. Researchers in the Netherlands have developed a scheme where the input energy requirements for integrated supercontinuum generation are drastically lowered by orders of magnitude for bandwidth generation of the order of 500–1000 nm. They achieved an efficiency enhancement by factors reaching 2800 through sign-alternating dispersion in a CMOS-compatible silicon nitride waveguide. They showed that the […]
Creating ‘ghostly mirrors’ for high-power lasers
Phys.org January 31, 2023 High power lasers have become useful scientific tools, but their large size is determined by their low damage-threshold optical media. A more robust and compact medium for amplifying and manipulating intense laser pulses is plasma. An international team of researchers (UK, Germany, Portugal) has demonstrated, experimentally and through simulations, that few-millijoule, ultra-short seed pulses interacting with 3.5-J counter-propagating pump pulses in plasma, stimulate back-scattering of nearly 100 mJ pump energy with high intrinsic efficiency, when detuned from Raman resonance. This is due to scattering off a plasma Bragg grating formed by ballistically evolving ions. Electrons are […]
High-performance visible-light lasers that fit on a fingertip
Phys.org January 4, 2023 Widely tunable and narrow-linewidth lasers at visible wavelengths are necessary for applications such as quantum optics, optical clocks, and atomic and molecular physics. At present, the lasers are benchtop systems, which precludes these technologies from being used outside research laboratories. A team of researchers in the US (Columbia University, Tufts University) has demonstrated a chip-scale visible laser platform that enables tunable and narrow-linewidth lasers from near-ultraviolet to near-infrared wavelengths. Using micrometre-scale silicon nitride resonators and commercial Fabry–Pérot laser diodes, they achieved coarse tuning up to 12.5 nm and mode-hop-free fine tuning up to 33.9 GHz with intrinsic linewidths […]
Milestone for laser technology
Science Daily December 5, 2022 To make free-electron lasers (FELs) smaller and more cost-effective, an international team of researchers (Israel, Japan, Germany, France, USA – UT Austin) has demonstrated seeded FEL lasing in the ultraviolet regime based on laser-plasma accelerator-driven free-electron laser in a seeded configuration, where control over the radiation wavelength was accomplished. The appearance of interference fringes, resulting from the interaction between the phase-locked emitted radiation and the seed, confirmed longitudinal coherence. Based on their work the researchers anticipate a navigable pathway to extreme-ultraviolet wavelengths, paving the way towards smaller-scale free-electron lasers, unique tools for a multitude of […]
Laser loops create ultrafast electric currents in solid materials
Nanowerk September 15, 2021 An international team of researchers (Germany, Spain, USA – the Flatiron Institute) predicted that a unique laser source could produce highly controllable electric currents in any bulk material. They focused on an intense laser beam comprised of only low-energy photons, which incorporates two circularly-polarized carrier frequencies. The polarization of the electromagnetic field of this beam plots a distinct shape in space and time. The combination of the two colors leads to a double-loop motion that pushes electrons in the solid in various directions. Together with the intense beam, the double-loop laser light produces many photons which […]
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 […]