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Author

Yuta Inose

Bio: Yuta Inose is an academic researcher from Kyoto University. The author has contributed to research in topics: Terahertz radiation & Resonant-tunneling diode. The author has an hindex of 1, co-authored 4 publications receiving 2 citations.

Papers
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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

Proceedings ArticleDOI
01 Sep 2019
TL;DR: In this article, simulations for oscillation of series-connected RTDs to realize higher output power were performed and the authors found factors which determine whether oscillation or domain formation occurs and the variation of the fabricated RTD areas should be within a few percent to realize the oscillation.
Abstract: We performed simulations for oscillation of series-connected RTDs to realize higher output power. We found factors which determine whether oscillation or domain formation occurs. The variation of the fabricated RTD areas should be within a few percent to realize the oscillation.

1 citations

Journal ArticleDOI
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 studied.
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 (HWHM) 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. As increasing the injection amplitude, we observed decrease of the noise component in the power spectrum, which manifests the free-running state, and alternative increase of the injection-locked component. The noise component and the injection-locked component had the same power at the threshold injection amplitude as small as $5\times10^{-4}$ of the oscillation amplitude. This threshold behavior can be qualitatively explained by Maffezzoni's model of noise reduction in general limit-cycle oscillators.

Cited by
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Journal ArticleDOI
TL;DR: In this paper , the authors show that the resonant-tunneling-diode (RTD) oscillator can be passively mode-locked by optical feedback and generate a terahertz frequency comb.
Abstract: Optical frequency combs in the terahertz frequency range are long-awaited frequency standards for spectroscopy of molecules and high-speed wireless communications. However, a terahertz frequency comb based on a low-cost, energy-efficient, and room-temperature-operating device remains unavailable especially in the frequency range of 0.1 to 3 THz. In this paper, we show that the resonant-tunneling-diode (RTD) oscillator can be passively mode-locked by optical feedback and generate a terahertz frequency comb. The standard deviation of the spacing between the comb lines, i.e., the repetition frequency, is reduced to less than 420 mHz by applying external bias modulation. A simulation model successfully reproduces the mode-locking behavior by including the nonlinear capacitance of RTD and multiple optical feedback. Since the mode-locked RTD oscillator is a simple semiconductor device that operates at room temperature and covers the frequency range of 0.1 to 2 THz (potentially up to 3 THz), it can be used as a frequency standard for future terahertz sensing and wireless communications.

3 citations

DOI
TL;DR: In this article , the phase control of an injection-locked RTD oscillator with a slot antenna and a device package that reduces external THz feedback to obtain continuous frequency tuning was demonstrated.
Abstract: Controlling the phase of terahertz (THz) waves is necessary for various applications, particularly beam steering with phased arrays. Resonant tunneling diodes (RTDs) are promising candidates for compact THz sources, and injection-locking phenomenon can be used to control the phase of RTD oscillators. In this study, we experimentally demonstrate the phase control of an injection-locked RTD oscillator. We fabricated an RTD oscillator with a slot antenna and developed a device package that reduces external THz feedback to obtain continuous frequency tuning. The free-running frequency varied from 380.5 to 386.7 GHz over a bias range of 0.61 to 0.65 V. To measure the phase of RTD oscillator, we constructed a heterodyne detection system in which all signals were well synchronized to achieve good phase measurement accuracy. The frequency of the RTD oscillator was locked to an injection signal of 383.2 GHz from an external source, and the phase was controlled by the bias voltage under the injection locking. The measured phase changed from −81° to +73° within the locking range. The bias-voltage dependence of the phase change reasonably agreed with the theoretical expectation.

2 citations

Proceedings ArticleDOI
29 Aug 2021
TL;DR: In this article, a heterodyne system for measuring the phase of terahertz (THz) waves with high accuracy was constructed and the phase change almost from −90° to +90° within the locking range, which agrees with the expectation derived from Adler's equation.
Abstract: We constructed a heterodyne system for measuring the phase of terahertz (THz) waves with high accuracy and achieved to control the phase of a resonant tunneling diode (RTD) oscillator using injection locking. The free-running oscillation frequency of the RTD THz oscillator was tuned from 380.5 to 386.7 GHz in the bias range of 0.61-0.65 V. In the phase measurement, we injected a signal of 383.2 GHz to the RTD THz oscillator and measured the phase with different free-running frequencies. The phase changed almost from −90° to +90° within the locking range, which agrees with the expectation derived from Adler's equation.

1 citations

Journal ArticleDOI
TL;DR: In this article , the phase control of an injection-locked RTD oscillator with a slot antenna and a device package that reduces external THz feedback to obtain continuous frequency tuning was demonstrated.
Abstract: Controlling the phase of terahertz (THz) waves is necessary for various applications, particularly beam steering with phased arrays. Resonant tunneling diodes (RTDs) are promising candidates for compact THz sources, and injection-locking phenomenon can be used to control the phase of RTD oscillators. In this study, we experimentally demonstrate the phase control of an injection-locked RTD oscillator. We fabricated an RTD oscillator with a slot antenna and developed a device package that reduces external THz feedback to obtain continuous frequency tuning. The free-running frequency varied from 380.5 to 386.7 GHz over a bias range of 0.61 to 0.65 V. To measure the phase of RTD oscillator, we constructed a heterodyne detection system in which all signals were well synchronized to achieve good phase measurement accuracy. The frequency of the RTD oscillator was locked to an injection signal of 383.2 GHz from an external source, and the phase was controlled by the bias voltage under the injection locking. The measured phase changed from −81° to +73° within the locking range. The bias-voltage dependence of the phase change reasonably agreed with the theoretical expectation.

1 citations

Proceedings ArticleDOI
03 Dec 2022
TL;DR: In this article , the authors reported the recent developments of resonant tunneling diodes and terahertz (THz) applications and their applications in the future wireless communication system.
Abstract: In the beyond 5G future wireless communication system, the terahertz (THz) band will be used not only for high data rate communication but also advanced sensing applications. THz oscillators using resonant tunneling diodes (RTDs) are a candidate of THz sources and suitable for these applications due to compactness, high efficiency, and various functionalities. In this paper, recent developments of RTD oscillators and THz applications are reported.