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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 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...
In this paper, we propose a new architecture of photomixer in order to develop a wideband and powerful photomixing THz source. It is achieved by a velocity-matched distributed photoconductor, in which the pump optical power is guided in a dielectric optical guide and slightly coupled to a low-temperature grown GaAs 1-mm-length photoconductor.
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...
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.
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.
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.
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...
It is shown from accurate on-wafer measurement that a low-temperature-grown GaAs photoconductor using a metallic mirror Fabry-Perot cavity can serve as highly efficient optoelectronic heterodyne mixer in the terahertz frequency range. Conversion losses of 22 dB at 100 GHz and ∼27 dB at 300 GHz were measured, which is an improvement by a factor of about 40 dB as compared with the previous values obtained...
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...
Narrow linewidth terahertz (THz) generation using a cascaded Brillouin fibre laser structure and a unitravelling carrier photodiode is investigated. Using two distributed feedback lasers separated by > 1 THz with 1 MHz initial linewidth, the use of the cascaded Brillouin laser greatly increases the linewidth reduction factor compared to a single Brillouin laser structure. The linewidth of the realised...
Here, we demonstrate the possibility of employing a novel low-loss dielectric material as substrate for free-space THz devices through the design, fabrication and characterization of broadband high-transparency high-pass mesh filters. Time-domain spectroscopy measurements show that a transmittance higher than 75% is achieved over a bandwidth of 1 THz.
By combining a UTC-PD as a THz emitter and a 400 GHz Schottky-based heterodyne detection, we realized an indoor THz link working up to 22 Gbps at 400 GHz carrier frequency with ultra-low THz power. The eye diagram at receiver is clearly opened are the system is working with only 1 µW received THz power.
It is shown that a continuous wave output power reaching 1.8 mW at 252 GHz can be generated by photomixing in a low-temperature-grown GaAs photoconductor using a metallic mirror-based Fabry-Pérot cavity thanks to an impedance matching circuit.
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