Phys.org September 27, 2024 Excitons in monolayer semiconductors offer strong light–matter coupling, spin–valley locking and exceptional tunability allowing electrical switching of their optical response due to efficient interactions of excitonic emitters with free charge carriers forming trions and Fermi polarons. However, there are major limitations to how fast the light emission of these states can be tuned, restricting most applications to an essentially static regime. An international team of researchers (Italy, Sweden, Germany, Japan) demonstrated switching of excitonic light emitters in monolayer semiconductors on ultrafast picosecond time scales by applying short pulses in the terahertz spectral range following optical injection. […]
Tag Archives: Photonics
Entangled photon pairs enable hidden image encoding
Phys.org September 4, 2024 Photon-pair correlations in spontaneous parametric down-conversion are ubiquitous in quantum photonics. The ability to engineer their properties for optimizing a specific task is essential, but often challenging in practice. Researchers in France demonstrated the shaping of spatial correlations between entangled photons in the form of arbitrary amplitude and phase objects. By doing this, they encoded image information within the pair correlations, making it undetectable by conventional intensity measurements. It enabled the transmission of complex, high-dimensional information using quantum correlations of photons, which could be useful for developing quantum communication and imaging protocols… read more. TECHNICAL ARTICLE
Researchers demonstrate new way to ‘squeeze’ infrared light
Science Daily June 10, 2024 Recent theoretical studies have suggested that transition metal perovskite oxide membranes can enable surface phonon polaritons in the infrared range with low loss and much stronger subwavelength confinement than bulk crystals. Such modes, however, have not been experimentally observed so far. An international team of researchers (USA – North Carolina State University, Lawrence Berkeley National Laboratory, Stanford University, SLAC National Accelerator Laboratory, Switzerland) studied the phonon polaritons in a 100 nm thick freestanding crystalline membrane of SrTiO3 transferred on metallic and dielectric substrates. They observed a symmetric-antisymmetric mode splitting which gave rise to epsilon-near-zero and Berreman […]
Breakthroughs in optical modulation using tunable 2D materials
Nanowerk April 26, 2024 Achieving distinctive modulation across short-wave infrared (SWIR) regions while enabling precise phase control at low signal loss within a compact footprint remains an ongoing challenge. By integrating CuCrP2S6 (CCPS) into silicon photonics microring resonators (MRR) an international team of researchers (United Arab Emirates, New York University) enhanced light-matter interaction and measurement sensitivity to minute phase and absorption variations. The devices exhibited low optical losses and excellent modulation efficiency. These results outperformed earlier findings on phase shifters based on TMDs. The study demonstrated distinct variations in electro-optic tuning sensitivity when comparing transverse electric and transverse magnetic modes, […]
Hybrid bound states in the continuum in terahertz metasurfaces
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 […]
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 […]