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Low-temperature-grown GaAs (LT-GaAs)-based Fabry-Pérot cavity photoconductors, designed for RF and THz optoelectronics applications using1550 nm lasers, are studied. The sub-sampling of continuous waves at frequencies up to 300 GHz is presented. The duty-cycle-limited conversion losses measured up to 67 GHz show that this GaAs-based photoconductor behaves as a nearly perfect photoswitch controlled...
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.
We study low-temperature-grown GaAs (LT-GaAs) based ultrafast Fabry-Pérot cavity photoconductors, designed for THz optoelectronics applications using 1550 nm pulsed lasers. We present here, as a proof of concept, the under-sampling of continuous RF waves up to 67 GHz.
We present a new design of InGaAs metal-semiconductor-metal (InGaAs-MSM) photodetectors placed in optical resonant cavities in order to reduce inter-electrode spacing while keeping a high photoresponse. Its static and dynamic photoresponse properties have been measured by means of a photomixing experiment up to 67 GHz, showing the potential of this device for GHz and THz applications.
This paper presents the development and use of high-efficiency Unitravelling carrier photodiodes for THz communications. Using these devices, high output power is obtained close to the mW level. THz wireless links demonstration is also presented using these devices, using high-level modulation schemes (QAM-16) and 32 Gbit/s data-rate. This result demonstrates the capability of the UTC-PD devices of...
We present a current study of mid-IR isolator using nonreciprocal (NR) magnetoplasmonic InSb mirror. The reflectivity of n-type InSb surface was calculated using Rigorous Coupled Wave Algorithm (RCWA) method. We report magnetooptical (MO) effect for low external magnetic field (B=0.1T), which can be enhanced by a plasmonic grating.
We investigate optical resonant cavities using metallic mirror in order to increase the absorption in low-temperature-grown GaAs (LT-GaAs) based photoconductors operating at telecom wavelength. Two different semi-transparent front mirrors are compared: the first one is a thin gold layer whereas the second one consists of a gold periodic array. We show that the generated photocurrent is 3 times higher...
Heterostructure low barrier diode (HLBD) based on AlGaInAs has been designed, fabricated and characterized for zero-bias millimetre-wave detection. Detectors with different heterostructures and various active areas have been tested in order to optimize their characteristics for low-level radiometric detection. We have measured the microwave performances of HLBD from DC to 220 GHz. A responsivity of...
Gyrotropic hexaferrite materials are believed to be very promising candidates for operation in non-reciprocal devices at terahertz frequencies. We present full permittivity and permeability tensor characterization of different hexaferrite crystalline and ceramic samples in a wide band (0.075–5 THz) using both an original magneto-optical Time-Domain-Spectrometry setup and a magneto-quasi-optical setup...
With the fast increase of mobile data transfers, wireless communications carrier frequencies have entered in the millimeter wave region and now they enter in the submillimeter or terahertz region. In this context photonic-based emitters have several advantages, we will present our communication links results using photomixers at 0.2, 0.4 and 0.6 THz.
We demonstrate a W-band bolometer based on a platinum nano-strip which is integrated with a waveguide probe on a polymer substrate. We measure a high thermal response of 49000 K/W thanks to the small size of the Pt resistor and the thermal properties of the polymer. Furthermore, its small thermal capacity allows to decrease the time constant to 2.2 ms. A good matching in the entire W-band is achieved...
A low power 278-GHz CMOS zero-IF heterodyne receiver is presented in this paper. The circuit includes a passive mixer, a baseband amplifier, a 278-GHz triple push sub-harmonic injection locked oscillator and an integrated antenna. The receiver measured maximum conversion gain is −12 dB and the DC power consumption is 47 mW. The on-chip antenna size is 390×280 μm2. The heterodyne receiver is used as...
Thin film grounded coplanar waveguides using Parylene-C and Cyclic-Olefin-Copolymer (COC) as low loss thin film have been fabricated and characterized up to 320 GHz. Attenuation around 1.75 dB/mm has been measured at 300 GHz with ∼5-μm-thick Parylene-C film, close to the attenuation obtained with Cyclo-Olefin Copolymer film of similar thickness.
Chip scale terahertz dielectric waveguides, consisting out of high resistivity silicon as a core material have been fabricated. The waveguide loss is measured to be ∼1dB/cm at both 1 THz and 2.5 THz.
We present investigations of photoconductive antennas (PCA) based on low temperature grown GaAs (LT GaAs) on silicon substrates for terahertz (THz) detection and generation. The PCAs consist of 2 μm thick layers of LT GaAs bonded on a high resistivity silicon substrate in order to reduce the intrinsic absorption losses around 8 THz due to a strong phonon resonance in GaAs. Using 20 fs long pump pulses...
Ultrafast photoconductors using GaAs implanted by low energy N+ ions (< 55 keV) are fabricated and characterized up to 320 GHz by means of a photomixing experiment. Around 90 μW of output power was obtained at 290 GHz with a 2-μm-diameter photoconductor based on GaAs implanted with a main dose of 1.1×1012 cm−2 and a subsequent annealing at 600°C.
Far-field terahertz imaging is limited by diffraction to low resolutions in the 50 μm range. On the other hand, near-field optical nanoscopy is a recent technique that shows permittivity contrasts at the nanoscale. We present here images of graphene layers on SiO2 obtained by scattering scanning near-field nanoscopy at 2.5 THz that show high contrasts.
The first quadrature phase shift keying (QPSK) data link at 385 GHz, using a photonic-based terahertz (THz) emission and a double heterodyne THz detection, is reported. The QPSK signalling is investigated up to 16 Gbaud (32 Gbit/s) on a short range distance, with 20 µW received power levels.
In this work, a pulse shaper in coplanar technology intended for the unlicensed band up to the THz region is designed, fabricated, and measured. This broadband frequency range is of great interests as it offers very high data rate communication in local area networks. The technique employs tailored coplanar lines that have been designed using an exact analytical series solution of the synthesis problem...
Narrow linewidth THz generation using a cascaded Brillouin fibre laser structure and a unitraveling carrier photodiode is proposed. Using two distributed feedback lasers separated by > 1 THz with 1 MHz initial linewidth, the linewidth of the realized THz source is found to be < 100 Hz at 1014.7 GHz without use of any active stabilization of the laser cavity or any microwave reference.
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