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Strong quasi-cw terahertz fields accelerate and recollide electron-hole pairs injected by a near-ir laser into GaAs quantum wells. A frequency comb is emitted, with up to 18 teeth separated by twice the terahertz frequency.
Increasing coupling of terahertz radiation into a low dispersion, broadband two-wire waveguide is an important issue to address. To resolve this, we demonstrate an active two-wire waveguide with higher performance compared to its passive counterpart.
The two-photon photovoltaic effect is demonstrated in gallium arsenide at 976 and 1550 nm wavelengths. A waveguide photodiode biased in its fourth quadrant is used to harvest electrical power from photons lost to two-photon absorption.
We demonstrated electrically-driven subwavelength surface plasmonic nano-circuits integrating gap-plasmon emitting nano-LEDs and deep-subwavelength slot waveguides with a cross-sectional area of ∼0.016λ2 for the first time. Owing to the Purcell enhancement within the extremely small, metal-clad active region of the nano-LED, gap-plasmons are extracted efficiently. The gap-plasmons propagating along...
We experimentally demonstrate mid-infrared difference frequency generation in suspended 181-nmthick GaAs waveguides. The extreme form-birefringence in the nanoslab waveguide enables phase-matching between the CW signal (1550 nm), pump (1025 nm), and idler (3000 nm).
GaAs1−xBix laser diodes (LDs) with low temperature dependence of the oscillation wavelength (dλ/dT) are demonstrated. The value dλ/dT for a GaAs0.97Bi0.03 LD was as low as 0.16 nm/K. This reduction is attributed to a reduction in the temperature coefficient of the band gap.
We demonstrate second harmonic generation in photonic crystal cavities in (001)- and (111)-oriented GaAs, with fundamental resonance at 1800nm, leading to second harmonic below the GaAs bandgap. Below bandgap operation minimizes linear and nonlinear absorption.
An integrated Mach-Zehnder intensity modulator for laser radiation at the wavelength 780 nm is demonstrated for the first time. The device features a double heterostructure GaAs/AlGaAs electro-optic phase modulator. The estimated insertion loss is less than 2.5 dB and the extinction ratio is 3.3 dB.
By analyzing how carrier relaxation rates depend on pump fluence and sample temperature, we conclude that states of TbAs embedded in GaAs are saturable. This suggests the existence of a bandgap for TbAs nanoparticles.
We study the coherent dynamics of cyclotron resonance in ultrahigh-mobility two-dimensional electron gases via time-domain terahertz magneto-spectroscopy. We show that superradiant damping is the dominant decoherence mechanism at low temperatures.
We present evidence from transient-absorption spectra for quantum electron-hole droplets in GaAs quantum wells. Quantum droplets have a two-particle correlation function characteristic of a liquid, but, unlikemacroscopic droplets, have quantized binding energy.
Local terahertz fields of multiple 10 MV/cm tailored in gold metamaterials drive electronic interband transitions in intrinsic GaAs. The bandgap exceeds the THz photon energy 400-fold. Photoluminescence microscopy maps the THz near-field distribution.
This article describes a GaAs PIN photodiode was directly grown on a Si substrate in which CMOS-based transimpedance amplifier (TIA) was fabricated using general Si CMOS process. This monolithic integration device was successfully demonstrated.
We demonstrate control of energy states in epitaxially-grown sub-monolayer quantum dots by engineering of the internal bandstructure of the dots. We show shifts of the quantum dot ground state energy from 1.38eV to 1.68eV.
Ultrafast dynamics of photo-excited electrons with non-equilibrium distribution in GaAs has been studied on femtosecond time scale, by means of energy- and angle-resolved two-photon photoelectron spectroscopy. Fundamental scattering processes governing their energy relaxation are elucidated.
Both electronic and phonon coherence in bulk GaAs is studied using an interference experiment of electron-phonon coupled states induced by two phase-locked femtosecond pulses. Full coherence remains within ∼ 45 fs at room temperature.
The relation between dipole and momentum matrix elements in crystals, treated with periodic boundary conditions, is revisited. A correction term to standard expressions is found to be large for bulk GaAs, small for THz transitions.
We demonstrate a photo-induced oxidation technique for tuning GaAs photonic crystal cavities using a 390 nm laser, and show that it is applicable to cavity arrays by tuning an individual cavity in a proximity-coupled cavity pair [1].
Gallium arsenide photonic crystal resonators are designed and fabricated for evanescent coupling to localized ensembles of rare-earth ions in crystalline hosts. These devices will enable nano-scale on-chip optical quantum memories.
We study impact-ionization-induced electroluminescence (EL) from a GaAs/AlGaAs heterostructure under high bias. In addition to k-space transfer (the Gunn effect), EL spectra indicate real-space (GaAs-to-AlGaAs) transfer. Microscopy shows strong EL near the anode.
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