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Simultaneous stabilization of two quantum cascade lasers operated at 2 and 3 THz has been demonstrated by using a multi-frequency THz source based on Mach-Zehnder-modulator-based flat comb generator (MZ-FCG) combined with a programmable optical filter.
We present a THz heterodyne detector based on a single layer graphene field effect transistor (GFET) integrated with a bowtie antenna at 400 GHz. The heterodyne detection is achieved by coupling RF and LO signals quasi-optically to the same GFET. The down converted IF signal is extracted via a coplanar stripline connected to the GFET source and drain terminals. The measured IF bandwidth is 5 GHz.
We have developed a phase-locking system of a terahertz quantum cascade laser (THz-QCL) using a hot electron bolometer mixer (HEBM) and a terahertz reference such as an amplifier/multiplier chain (AMC) or an optical-comb generator followed by a UTC-PD. We have demonstrated simultaneous phase-locking of two THz-QCLs. The phase-locked THz-QCLs can be used as local oscillators (LOs) of an HEBM. This...
A compact receiver MMIC for a 300 GHz wireless communication system has been developed in a 35 nm mHEMT technology. The circuit integrates an active frequency multiplier by three and a buffer amplifier for the LO signal, a single balanced, quadrature, fundamental resistive down-converter and an RF pre-amplifier. The chip measurements have shown that the receiver exhibits a conversion gain of −1 dB...
We give a comparison of sensitivity and power estimates for heterodyne receivers operating at common atmospheric science bands using Schottky mixer or low-noise amplifier front ends. The receiver estimates rely on commercially available mixer systems and reported low noise amplifier data.
We present results on the performance of a cryogenically cooled all-Schottky solid-state heterodyne receiver targeting the 2.06 THz neutral oxygen line. The receiver front end features low-parasitic Schottky diode mixer chips that are driven by a local oscillator (LO) source using Schottky diode based multipliers. The multiplier chain consists of a 38 GHz oscillator followed by a set of three cascaded...
The operating frequency of InP high electron mobility transistor (HEMT) based amplifiers has moved well in the submillimeter-wave frequencies over the last couple of years. Working amplifiers with substantial gain in waveguide packages has been reported beyond 700 GHz. When cooled cryogenically, they have shown significant improvement in their noise temperature. This has opened up the real possibility...
We present a novel heterodyne terahertz spectrometry scheme based on plasmonic photomixing, which is capable of offering large dynamic ranges and broad spectrometry bandwidths at room temperature.
There is a high need for >2 THz room temperature direct-detectors/harmonic-mixers to characterize THz optical sources, phase lock THz-QCLs as LO sources for multi-pixel receivers, and realize absolute frequency calibration sources for applications in astrophysics, earth science, and remote sensing. Thus, we have developed a WM-52 (WR-0.22) harmonic mixer for the 3–5 THz operation. The design, fabrication...
A limiting factor of GaAs Schottky diodes used as mixers in heterodyne receivers is their high intrinsic noise when compared to SIS or HEB devices. This work presents results on the numerical optimization of fundamental Schottky diode mixers, results which predict a significant improvement in the noise performance of current Schottky mixer technology in the THz band. The optimization of the Schottky...
This paper presents a fully-integrated ultrawideband receiver MMIC for high data rate communication at 240 GHz operating with a LO frequency of 60 GHz. The chip was fabricated in a 35 nm InGaAs-based metamorphic high electron mobility transistor technology. It comprises a frequency doubler followed by a buffer amplifier in the LO path, a LNA in the RF path and a subharmonic single balanced downconverter...
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