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Locally enhanced few-cycle terahertz transients at a sharp metal nanostructure enable a new scheme for ultrafast photoemission control and near-field characterization. We present nanoscale streaking based on electron dynamics in sub-wavelength confined driving fields at nanostructures that are governed by the momentary THz-field at the instance of photoemission. The locally enhanced THz-field allows...
Scattered x-rays were utilized for determination of the electron energy distributions at a gyrotron collector. Performed calculations and experiments demonstrated that scattering in the diagnostic window has only minor effect on the radiation spectra in the gyrotron-relevant conditions. The primary advantage of the proposed diagnostic scheme consists in reduction of the density of treated x-rays flux...
Terahertz (THz) photo-detectors, consisting of a r graphene nano-bridge and a plane antenna have been fabricated c and characterized. Hot electrons in graphene-bridge (GB) are generated after absorbing the incident THz photons. We measured the amplified thermal noise power from hot electrons to sense the absorbed THz power. By using this noise-thermometric technique, a THz photodetector with temperature...
Applications of THz photonics rely critically on efficient THz wave generation and detection. Here we report THz radiation from cesium and rubidium vapor plasma. By taking advantage of the very low ionization potential of cesium (3.89 eV) and rubidium (4.18 eV), we are able to produce a THz wave with an amplitude more than 8 times higher than nitrogen gas at the same pressure, showing the promise...
Phase grating structure has the ability to converge light. We have introduced it to couple with superconducting nanowire single photon detector (SNSPD) to enhance its response for light. The effects of the coupling structure parameters on the enhancement have been studied systematically by FDTD method. Our numerical simulation show that the optical density arriving on nanowires of SNSPDs can be enhanced...
Will recall the history of the Rydberg atom-microwave Cavity QED experiments at Ecole Normale Supérieure (ENS) and describe how they have allowed us to count photons non-destructively and to reconstruct and control non-classical states of light.
Refractive indices of a 1 mol % MgO-doped stoichiometric LiTaO3 (SLT) crystal in the region of 0.85 ∼ 1.59 THz and for the temperature range of 80 ∼ 300 K were deduced via the terahertz generation process using a fanned-out periodically poled SLT. In addition, temperature-dependent Sellmeier equation was derived.
We studied the carrier multiplication efficiency in bulk silicon using optical-pump/THz-probe spectroscopy. By the close analysis of the time resolved data, we observed the enhancement of the quantum efficiency due to carrier multiplication for incident photon energy above 4.1 eV. It agrees well with the results of photo current measurements. We believe that the present results enable us to correlate...
We show that due to Rashba spin-orbit coupling two-dimensional semiconductors can exhibit strong nonlinear optical response in the terahertz frequency regime. The spin-split of the parabolic energy band in semiconductors allows multiple-photon process to occur via inter-subband transitions. The steplike edges in the optical process correspond to the cut-off effect produced by the multiple-photon process.
Waveguiding of excitation beam and propagation of THz beam in a complex gradient environment were studied in an array of InP nanowires. Measurements by time-resolved THz spectroscopy accompanied by Monte-Carlo calculations of the response of localized charges enabled determination of transversal electron mobility.
We propose a 600 GHz data transmission of high definition television using the combination of a photonic emission using an uni-travelling carrier photodiode and an electronic detection, featuring a very low power at the receiver. Only 10 nW of THz power at 600GHz were sufficient to ensure real-time error-free operation. This combination of photonics at emission and heterodyne detection lead to achieve...
Microwave kinetic inductance detectors (MKIDs) promise high sensitivity, combined with device simplicity and intrinsic multiplexibility. We have measured the response and noise equivalent power (NEP) of an all-aluminium, antenna coupled MKID at 1.54 THz, both as a function of radiation power and as a function of readout power. Eight optical filters and a box-in-box configuration at the bath temperature,...
We have extended the discovery of ultrafast extrinsic photoconductivity in ErA:GaAs to the 1550 nm-driven continuous-wave (CW) photomixer. The photocurrent in the photomixer has been measured as a function of 1550 nm laser power and bias voltage. Then the first ever 1550 nm ErAs:GaAs photomixing transceiver was setup and THz power was successfully measured. The work done here represents the first...
We investigated a coherent THz link at 200 GHz, with variable data rate up to 11 Gbit/s, featuring the combination of a quasi-optic UTC-PD emitter and a high sensitivity electronic receiver. This coherent link relies on an optical frequency comb generator at emission to produce an optical beat note with 200GHz separation. BER testing has been carried out using an indoor link configuration and the...
We investigated the transient response of the solvated electron ejected by photodetachment from potassium ferrocyanide in water using time resolved terahertz spectroscopy (TSTS). We find that the measured frequency dependent conductivity can be well described by a Drude-Smith model, supplemented by a Lorentz model oscillating near 5 THz.
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