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Epitaxial low temperature grown GaAs (LT-GaAs) on silicon (LT-GaAs/Si) has the potential for terahertz (THz) photoconductive antenna applications. However, crystalline, optical and electrical properties of heteroepitaxial grown LT-GaAs/Si…
Ultrafast laser driven, single-cycle THz pulsed sources hold immense potential for scientific and industrial applications; however, their limited average power hinders their widespread application. In particular, applications where high…
A method for the generation of ultrarelativistic electron beams with high spin polarization is put forward, where a tightly-focused linearly-polarized ultraintense laser pulse interacts with a nonprepolarized transverse-size-tailored solid…
Experiments on ion acceleration by irradiation of ultra-thin diamond-like carbon (DLC) foils, with thicknesses well below the skin depth, irradiated with laser pulses of ultra-high contrast and linear polarization, are presented. A maximum…
Light incident upon materials can induce changes in their electrical conductivity, a phenomenon referred to as photoresistance. In semiconductors, the photoresistance is negative, as light-induced promotion of electrons across the band gap…
Mixing the fundamental ($\omega$) and the second harmonic (2$\omega$) waves in gas phase is a widely employed technique for emitting terahertz (THz) pulses. The THz generation driven by bi-chromatic fields can be described by the…
Ultrafast carrier and phonon dynamics at the buried heterointerface of GaP/Si(001) are investigated by means of two-color pump-probe reflectivity measurements. The carrier-induced reflectivity signal exhibits a resonant enhancement at…
Like many optoelectronics, the highest quality III-V solar cells start out as thin single-crystalline multilayers on GaAs substrates. Separating these device layers from their growth substrate enables higher performing devices and wafer…
We present two compact ultrafast electron injector designs with integrated focusing that provide high peak brightness of up to $1.9*10^{12} A/m^2Sr^2$ with 10s of electrons per laser pulse using silicon carbide electrodes and silicon…
We report on generation of pulsed broadband terahertz radiation utilizing the inverse spin Hall effect in Fe/Pt bilayers on MgO and sapphire substrates. The emitter was optimized with respect to layer thickness, growth parameters,…
Semi-insulating, undoped, Liquid Encapsulated Czochralski (SI-U LEC) GaAs detectors have been irradiated with 1MeV neutrons, 24GeV/c protons, and 300MeV/c pions. The maximum fluences used were 6, 3, and 1.8~10$^{14}$ particles/cm$^{2}$…
We investigate short pulse illumination of a high-speed extended-InGaAs photodiode at cryogenic temperatures towards its use in control and readout of superconducting qubits. First, we demonstrate high detector responsivity at 1550 nm…
We report on the new optical gating technique used for the direct photoconductive detection of short pulses of terahertz radiation with the resolution up to 250 femtoseconds. The femtosecond optical laser pulse time delayed with respect to…
Terahertz (THz) emission by two-color, ultrashort optical pulses interacting with underdense helium gases at ultrahigh intensities ($> 10^{19}\,\mathrm{W/cm}^2$) is investigated by means of 3D particle-in-cell simulations. The THz field is…
Cs-based semiconductors like $\mathrm{Cs_3Sb}$ and $\mathrm{Cs_2Te}$ are currently used as photocathodes in particle accelerators. Their performance as electron sources critically depends on their interaction with intense laser sources. In…
Using two-dimensional THz spectroscopy in combination with numerical models, we investigate the dynamics linked to carrier multiplication caused by high-field THz excitation of the low-gap semiconductor InSb. In addition to previously…
We experimentally observe the fast relaxation and relatively slow recombination dynamics of photogenerated electrons/holes in an epitaxial graphene-on-Si heterostructure under pumping with a 1550-nm, 80-fs pulsed fiber laser beam and…
A device has been built and tested, in which a ceramic superconducting cathode and a copper anode cause electrical discharges in low pressure gases, at temperatures between 50 and 70 K. The electrodes are connected to a capacitors array…
As one of the most important semiconductors, silicon (Si) has been used to fabricate electronic devices, waveguides, detectors, and solar cells etc. However, its indirect bandgap hinders the use of Si for making good emitters1. For…
We report bilayer-graphene field effect transistors operating as THz broadband photodetectors based on plasma-waves excitation. By employing wide-gate geometries or buried gate configurations, we achieve a responsivity $\sim 1.2V/W (1.3…