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Terahertz (THz) and sub-THz frequency emitter-detector technology is receiving increasing attention because of key apphcations in several fields. In particular, ultrafast THz receivers are desired for compact, ultrafast spectroscopy and communication systems. While most of the available THz detectors (thermal, FET …) are currently limited in response time by slow thermal processes and/or by the read-out...
A new Si/Ge/Si heterojunction based waveguide photodetector has been demonstrated in order to reduce the fabrication cost, increase the responsivity, and improve process robustness. State of the art characteristics in terms of dark current, responsivity and bandwidth have been obtained. Furthermore, such photodetectors were characterized in avalanche mode in order to improve the sensitivity and reduce...
Silicon is the mainstream material in the electronic industry and it is rapidly expanding its dominance into the field of photonics. Indeed, silicon photonics has been the subject of intense research activities to pave the way for next generation of energy-efficient high-speed computing, information processing and communications systems. The trend is to use optics in intimate proximity to the electronic...
Silicon-based photonics has generated a strong interest in the last years, mainly for optical telecommunications and optical interconnects in microelectronic circuits and industrial breakthroughs have been even performed by companies like IBM, Luxtera, INTEL, and ST Microelectronics. The main future rationales are the reduction of photonic system costs, the increase of the number of functionalities...
Silicon-based photonics has generated a strong interest in recent years, mainly for optical telecommunications and optical interconnects in microelectronic circuits. The main rationales of silicon photonics are the reduction of photonic system costs and the increase of the number of functionalities on the same integrated chip by combining photonics and electronics. In this paper, we will present recent...
We demonstrate a reduction of loss and group velocity dispersion (GVD) of THz plasmonic waveguides by using a low-loss thin flexible substrate. We present a numerical calculation of the effect of the substrate thickness on the GVD. We show experimentally low absorption and weak distortion of the propagated THz pulses along a THz plasmonic waveguide on a flexible 58µm-thick polyimide substrate.
First demonstrations of high speed silicon optical modulators fabricated on 300 mm silicon-on-insulator (SOI) wafers in CMOS foundry are presented. Both ring resonator and Mach Zehnder structures show 10 Gbit/s modulation. Small signal electro-optical bandwidth up to 20 GHz has been achieved, demonstrating the possibility of 40 Gbps data-rate transmission.
This paper reports on high speed Ge photodetectors integrated in Si waveguides which present very low dark current (25nA @-1V). 40Gbit/s operation under zero bias was reported at a wavelength of 1.55μm.
Experimental results of a silicon modulator based on carrier depletion in a PIPIN diode integrated in a Mach-Zehnder interferometer, are presented. At 40 Gbit/s, the modulator exhibits 6.6 dB extinction ratio and 6 dB optical loss.
40Gbit/s optical modulators based on carrier depletion effect and germanium photodetectors integrated in silicon waveguides have been demonstrated at a wavelength of 1.55µm.
The main properties of planar Goubau waveguides in the THz range are reported. Attenuation, dispersion and electric field confinement are measured using a guided-wave spectroscopy system based on a freely positionable electro-optic detector, and simulated using 3D electromagnetic field solver.
Silicon modulator based on interdigitated PN junctions integrated in a ring resonator is experimentally demonstrated, showing a 4 dB Extinction Ratio at 10 Gbit/s.
We report terahertz time-domain spectroscopy system based on Er:fiber laser at 1.55 μm wavelength. Ion-irradiated In0.53Ga0.47As photoconductive antenna is used as emitter. The detection is based on a phase modulation detection scheme in DAST electro-optic sensor.
The performances increase at low temperature make the SiGe HBT a masterpiece for cryogenic circuits. The time-progressive enhancement of f T and f MAX toward the THz frequency at room and at cryogenic temperatures is presented along with STMicroelectronics and IBM successive HBTs generations. The influence of the Ge content and graduality into the base is discussed, highlighting the...
We report recent experimental results of two kinds of photodetectors developed in the framework of the European project HELIOS: InAlAs-InGaAs metal-semiconductor-metal photodetectors and germanium photodetectors.
We report the transfer of a GHz modulation from an optical carrier at telecom wavelengths to a free space THz beam. THz radiation-tunable from 300 GHz to 1.2 THz- is generated by mixing two telecom lasers with an offset frequency in an ultrafast In0.53Ga0.47As photoconductive device coupled to a broadband antenna. A maximum modulation rate of 20 GHz has been achieved, and the bandwidth is independent...
In order to support the communication needs of our society, carrier frequencies for wireless communication networks in the terahertz frequency range will be an almost forced choice. For instance, the technology of choice to encode high-frequency data signals onto a terahertz carrier is still an open issue. This article investigates the transfer of a gigahertz modulation from an optical carrier at...
The evolution of silicon optical modulators is recalled, from the first effect demonstrations to the characterization of high-performance devices integrated in optical waveguides. Among possibilities to achieve optical modulation in silicon-based materials, the carrier depletion effect has demonstrated good capacities. Carrier depletion in Si and SiGe/Si structures has been theoretically and experimentally...
We report the generation of continuous terahertz waves from microwave frequencies up to 2 THz obtained by photomixing two optical waves at 1.55-mum wavelengths in an optimized ion-irradiated In0.53Ga0.47As interdigitated photomixers. Output powers greater than 40 nW at 0.5 THz and 10 nW at 1 THz have been achieved. The optimum excitation conditions regarding optical power and bias voltage are discussed.
We present a fiber-based 2-port THz electro-optic sampling system at 1.55 mum wavelength. Frequency components are extended up to 2 THz and the dynamic range is larger than 40 dB regardless of the direction of the electromagnetic wave propagating in the waveguide. The symmetrical 2-port pigtailed electro-optic probe allows to determine the direction of propagation of the guided picosecond electromagnetic...
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