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Journal ArticleDOI

Low-noise heterodyne detection of terahertz waves at room temperature using zero-biased Fermi-level managed barrier diode

01 Sep 2018-Electronics Letters (The Institution of Engineering and Technology)-Vol. 54, Iss: 18, pp 1080-1082
TL;DR: In this paper, a Fermi-level managed barrier (FMB) diode was used for the first time for the heterodyne detection of terahertz waves.
Abstract: A Fermi-level managed barrier (FMB) diode was used for the heterodyne detection of terahertz waves for the first time. A quasi-optical module integrating an FMB diode and a broadband trans-impedance amplifier exhibited an intermediate frequency bandwidth of 11 GHz. A very low noise-equivalent-power of 1.1 × 10−18 W/Hz was achieved at ∼300 GHz with a very low local oscillator power of 6 × 10−6 W.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a thermo-optic effect based silica optical phased array (OPA) chip was developed and evaluated its tunability of phases of lightwaves, whose phases are generated from four arrayed uni-travelling-carrier photodiodes based on heterodyne photomixng.
Abstract: We developed a thermo-optic effect based silica optical phased array (OPA) chip and evaluated its tunability of phases of lightwaves. The THz waves, whose phases are controlled by the OPA chip, are generated from four arrayed uni-travelling-carrier photodiodes (UTC-PDs) based on heterodyne photomixng. Meanwhile, the UTC-PDs, which integrated with $4\times 4$ slot antennas, are fabricated on a monolithic InP substrate chip for 300-GHz wave beam combining and steering. Through the optoelectronic THz-wave phase control, the feasibility of 300-GHz beam continuous steering is successfully demonstrated in a range of 50°.

26 citations

Journal ArticleDOI
23 Feb 2021
TL;DR: In this paper, the injection-locking properties of a resonant-tunneling-diode terahertz oscillator in the small-signal injection regime with a frequency-stabilized continuous THz wave were investigated.
Abstract: We studied the injection-locking properties of a resonant-tunneling-diode terahertz oscillator in the small-signal injection regime with a frequency-stabilized continuous THz wave. The linewidth of the emission spectrum dramatically decreased to less than 120 mHz (half width at half maximum) from 4.4 MHz in the free running state as a result of the injection locking. We experimentally determined the amplitude of injection voltage at the antenna caused by the injected THz wave. The locking range was proportional to the injection amplitude and consistent with Adler’s model. While increasing the injection amplitude, we observed a decrease in the noise component of the power spectrum, which manifests the free-running state, and an alternative increase in the injection-locked component. The noise component and the injection-locked component had the same power at the threshold injection amplitude as small as 5 × 10−4 of the oscillation amplitude. This threshold behavior can be qualitatively explained by Maffezzoni’s model of noise reduction in general limit-cycle oscillators.

10 citations

Journal ArticleDOI
30 Nov 2020-Sensors
TL;DR: A new principle for distance measurement in the terahertz-wave range is introduced using a resonant-tunneling-diode (RTD) oscillator as a source and relying on the frequency-modulated continuous-wave (FMCW) radar technique.
Abstract: We introduce a new principle for distance measurement in the terahertz-wave range using a resonant-tunneling-diode (RTD) oscillator as a source at 511 GHz and relying on the frequency-modulated continuous-wave (FMCW) radar technique. Unlike the usual FMCW radar, where the sawtooth frequency modulation is applied to the carrier, we propose applying it to a subcarrier obtained by amplitude modulation; this is advantageous when the source cannot be controlled precisely in oscillation frequency, but can easily be modulated in amplitude, as is the case of the RTD oscillator. The detailed principle and a series of proof-of-concept experimental results are presented.

10 citations


Cites methods from "Low-noise heterodyne detection of t..."

  • ...We used a Fermi-level-managed-barrier-diode (FMBD) detector [17], which in our particular setup turned out to have a signal-to-noise ratio about 10 dB better than another high-speed terahertz-wave detector that we tried, namely a Schottky-barrierdiode (SBD) detector....

    [...]

  • ...We used a Fermi-level-managed-barrier-diode (FMBD) detector [17], which in our particular setup turned out to have a signal-to-noise ratio about 10 dB better than another high-speed terahertz-wave detector that we tried, namely a Schottky-barrier-diode (SBD) detector....

    [...]

Journal ArticleDOI
25 Jun 2021-Sensors
TL;DR: In this paper, the authors used a resonant-tunneling-diode (RTD) oscillator as the source of a terahertz-wave radar based on the principle of the swept-source optical coherence tomography (SS-OCT).
Abstract: We used a resonant-tunneling-diode (RTD) oscillator as the source of a terahertz-wave radar based on the principle of the swept-source optical coherence tomography (SS-OCT). Unlike similar reports in the terahertz range, we apply the stepwise frequency modulation to a subcarrier obtained by amplitude modulation instead of tuning the terahertz carrier frequency. Additionally, we replace the usual optical interference with electrical mixing and, by using a quadrature mixer, we can discriminate between negative and positive optical path differences, which doubles the measurement range without increasing the measurement time. To measure the distance to multiple targets simultaneously, the terahertz wave is modulated in amplitude at a series of frequencies; the signal returning from the target is detected and homodyne mixed with the original modulation signal. A series of voltages is obtained; by Fourier transformation the distance to each target is retrieved. Experimental results on one and two targets are shown.

8 citations

Journal ArticleDOI
TL;DR: In this article, a zero-biased Fermi-level managed barrier diode that was packaged with a rectangular-waveguide-input port was developed for direct (square-law) detection operations, the fabricated module exhibited a 3 dB bandwidth covering the whole WR-3 band.
Abstract: A zero-biased Fermi-level managed barrier diode that was packaged with a WR-3 rectangular-waveguide-input port was developed. For direct (square-law) detection operations, the fabricated module exhibited a 3 dB bandwidth covering the whole WR-3 band. The intermediate frequency bandwidth in heterodyne detection was, therefore, dominated by the bandwidth of the integrated preamplifier, and it was measured to be about 40 GHz. The minimum noise-equivalent power obtained was as low as 7 × 10 -18 W/Hz at around 300 GHz even with a very low local oscillator power of 30 μW.

7 citations

References
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Journal ArticleDOI
TL;DR: The state-of-the-art of terahertz heterodyne receivers are reviewed in this paper, with a focus on front-end components such as mixers and local oscillators.
Abstract: The state-of-the art of terahertz heterodyne receivers are reviewed. Emphasis is placed on front-end components such as mixers and local oscillators. The back-end technology is described to a lesser extent. Recent developments, which are expected to have a major impact in the future, are also discussed.

179 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present the design and fabrication of a low-noise fixed-tuned 300-360 GHz sub-harmonic mixer, featuring an anti-parallel pair of planar Schottky diodes fabricated by the University of Virginia and flipchipped onto a suspended quartz-based microstrip circuit.
Abstract: This letter presents the design and fabrication of a low-noise fixed-tuned 300-360-GHz sub-harmonic mixer, featuring an anti-parallel pair of planar Schottky diodes fabricated by the University of Virginia and flip-chipped onto a suspended quartz-based microstrip circuit. The mixer exhibits a double side band (DSB) equivalent noise temperature lower than 900K over 18% of bandwidth (300-360-GHz), with 2 to 4.5mW of local oscillator (LO) power. At room temperature, a minimum DSB mixer noise temperature of 700K and conversion losses of 6.3dB are measured at 330GHz.

138 citations

Journal ArticleDOI
TL;DR: In this article, a monochromatic sub-terahertz signal generation technique using an optical comb signal, arrayed waveguide gratings (AWGs), and a uni-traveling carrier photodiode (UTC-PD) for spectroscopic applications is presented.
Abstract: We present a monochromatic sub-terahertz signal generation technique using an optical comb signal, arrayed waveguide gratings (AWGs), and a uni-traveling carrier photodiode (UTC-PD) for spectroscopic applications. This scheme offers random or continuous frequency tuning in the range between 100 GHz and up to 1 THz. In addition, since a RF synthesizer is employed as a reference signal source of the photonic frequency multiplier, frequency locking with external instruments and reliable operation are offered. Highly coherent optical comb signal for the photonic frequency multiplication provides a narrow linewidth and very low phase noise in the generated sub-terahertz signal. For 125 GHz, the phase noise is approximately -92 dBc/Hz at the offset frequency of 10 kHz. This is larger than that of the 25-GHz RF source by about 13 dB and agrees well with the theory regarding phase noise multiplications due to frequency multiplication. For generating monochromatic signals, unwanted spurious signals are suppressed in the optical domain over a wide range with two AWGs, and the suppression ratio is expected to be better than 46 dBc. Utilizing the implemented sub-terahertz signal generator with a J-band UTC-PD module, absorption lines of N2O were measured in the frequency range between 240 and 360 GHz and compared with theoretical calculations.

92 citations

Journal ArticleDOI
TL;DR: In this article, the authors present their ongoing work on terahertz heterodyne imaging techniques derived from space science applications and components and provide an introductory information and general techniques.
Abstract: The authors present their ongoing work on terahertz heterodyne imaging techniques derived from space science applications and components. In Part I, introductory information and general techniques are provided. Part II contains descriptions of four different heterodyne imaging instruments that have been established at the authors’ facilities. In Part III selected applications are discussed. Parts II and III will appear in subsequent issues of this journal.

61 citations

Journal ArticleDOI
TL;DR: In this paper, an InP/InGaAs heterobarrier rectifier called a Fermi-level managed barrier (FMB) diode was developed for attaining broadband and low-noise terahertz (THz) wave detection.
Abstract: An InP/InGaAs heterobarrier rectifier called a Fermi-level managed barrier (FMB) diode was developed for attaining broadband and low-noise terahertz (THz) wave detection. The barrier height was controlled by doping in an InGaAs layer, achieving a very small barrier-height of 70 meV. The intrinsic zero-biased differential resistance obtained was 110 Ω for an FMB diode with a 0.4 µm2 junction area. The fabricated device assembled in a quasi-optical module detected THz-wave signals at frequencies from 200 GHz to 1 THz at room temperature. The peak current and voltage sensitivities were respectively 3.7 A/W and 1110 V/W at 300 GHz for a zero-biased condition. An FMB diode module with an integrated preamplifier was also developed for characterizing its performance in practical use. Signal detection at frequencies from 160 GHz to 1.4 THz was attained with a high sensitivity of 3.2 MV/W and a low noise-equivalent power of 3.0 pW/ at 300 GHz.

52 citations