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We report saturable absorption in multilayer epitaxial graphene at 4.7 μm wavelength using mid-infrared quantum cascade laser. From z-scan and differential transmittance measurements, we demonstrate an enhancement of the transmittance of 9 %, attributed to the Pauli blocking effect in the graphene layers. We found that the saturation intensity is in the range of MW/cm2. Our results show the potential...
Photonic and electronic integration technology is pushed forward strongly by the telecommunication market to reduce the size and the costs of each component. Electro-optical terahertz (THz) technology based on the communication wavelength of 1.55 μm can directly benefit from the development of these integration techniques. Thus, continuous wave (cw) THz spectroscopy systems bear great potential to...
This paper presents high-efficiency Unitravelling carrier photodiodes for THz communications. Using high-level modulation schemes, QAM-16 and 32 Gbit/s data-rate is obtained using these devices, that combine high power level and linear behavior, mandatory for high-spectral efficiency data links in the THz range.
Germanium-on-silicon waveguides are designed, fabricated and characterized with a novel near-field infrared spectroscopy technique that allows on-chip investigation of the in-coupling efficiency. On-chip propagation along bends and straight sections up to 0.8 mm is demonstrated around λ = 6 μm.
We compare the emission power of GaAs, InGaAs and InAs as function of excitation photon energy. We find that the carrier excess excitation energy is more relevant to explain their performance difference than their mobilities. We conclude that ballistic transport after photoexcitation is the dominant mechanism for terahertz emission and that the relative importance of drift current in comparison to...
THz air photonics allow for the generation and detection of single-cycle sub-40 fs THz transients, which we use in a THz time-domain spectrometer to investigate the transmission properties of molecular crystalline materials in the ultrabroadband frequency window from 0.3 THz to more than 40 THz. We compare the obtained results with FTIR measurements to validate the THz-TDS results at large frequencies...
We report on infrared transmission and reflectivity experiments performed on Cd3As2 in a wide range of the photon energies and magnetic fields. The observed magneto-optical response unambiguously indicates the presence of 3D massless charge carriers. The detailed analysis of cyclotron resonances implies the presence of massless Kane electrons at a large energy scale, while the symmetry-protected 3D...
We present the theory of fast electro-optic correlations when applied to quantized fields. We find that, contrary to standard spectrometry or Hanbury Brown and Twiss arrangements, which are inherently based on destructive detection, electro-optic correlations fulfill the conditions of quantum non-demolition measurements. This property allows most notably the measurement of first and second order correlation...
Silicon-based integrated circuit technology provides a great platform for enabling compact, efficient, low-power, chip-scale THz systems for new applications in sensing, imaging and communication beyond the niche scientific applications that the spectrum is currently known for. While this is partially facilitated by scaling that has pushed device cut-off frequencies (ft, fmax) up into the sub-THz...
Terahertz light-matter interactions within a semiconductor-filled waveguide can be tuned in space and time via photoexcited regions created on ultrafast time scales and sub-THz wavelength length scales by a patterned optical pulse. These light-induced metal-dielectric structures can be used to dynamically modify the photonic band structure of THz light within the waveguide, controlling the amplitude,...
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