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Iwao Hosako

Bio: Iwao Hosako is an academic researcher from National Institute of Information and Communications Technology. The author has contributed to research in topics: Comb generator & Terahertz radiation. The author has an hindex of 5, co-authored 17 publications receiving 329 citations.

Papers
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Journal ArticleDOI
TL;DR: 40-Gb/s W-band 16-QAM radio-over-fiber signal is optically synthesized using dual-polarization QPSK modulator and its wireless transmission within FEC limit is demonstrated with optical self-heterodyne detection and digital signal processing.
Abstract: The generation of a 40-Gb/s 16-QAM radio-over-fiber (RoF) signal and its demodulation of the wireless signal transmitted over free space of 30 mm in W-band (75-110 GHz) is demonstrated. The 16-QAM signal is generated by a coherent polarization synthesis method using a dual-polarization QPSK modulator. A combination of the simple RoF generation and the versatile digital receiver technique is suitable for the proposed coherent optical/wireless seamless network.

208 citations

Proceedings ArticleDOI
18 Sep 2011
TL;DR: In this article, a 40-Gb/s W-band 16-QAM radio-over-fiber signal is optically synthesized using dual-polarization QPSK modulator.
Abstract: 40-Gb/s W-band 16-QAM radio-over-fiber signal is optically synthesized using dual-polarization QPSK modulator. Its wireless transmission within FEC limit is demonstrated with optical self-heterodyne detection and digital signal processing.

106 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

Proceedings ArticleDOI
06 Mar 2011
TL;DR: In this article, the authors demonstrated broadband comb generation using a Mach-Zehnder-modulator-based flat comb generator with an optical feedback loop, which was successfully generated by increment of the modulation depth.
Abstract: We demonstrated broadband comb generation using a Mach-Zehnder-modulator-based flat comb generator with an optical feedback loop. A 1 THz-width comb signal was successfully generated by increment of the modulation depth.

9 citations

Journal ArticleDOI
TL;DR: Using a frequency-tunable optical comb generated from a Mach-Zehnder-modulator-based flat comb generator (MZ-FCG) and a nonlinear optical fiber, a frequency measurement of continuous terahertz wave sources with the frequency of 0.1 and 0.6 THz is demonstrated by an electro-optic sampling method.
Abstract: Using a frequency-tunable optical comb generated from a Mach–Zehnder-modulator-based flat comb generator (MZ-FCG) and a nonlinear optical fiber, we demonstrated a frequency measurement of continuous terahertz wave sources with the frequency of 0.1 and 0.6 THz by an electro-optic sampling method. We clearly observed beat signals between the terahertz source and the optical two-tone extracted from the optical comb, allowing us to determine the absolute frequency. Owing to the wide comb spacing of the MZ-FCG, this method has a high potential for the high-speed measurement of the frequency of terahertz wave sources.

7 citations


Cited by
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Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: A wireless sub-THz communication system near 237.5 GHz with one to three carriers and up to 100 Gbit/s with state-of-the-art active I/Q-MMIC at the Rx is demonstrated.
Abstract: A wireless communication system with a maximum data rate of 100 Gbit s−1 over 20 m is demonstrated using a carrier frequency of 237.5 GHz. The photonic schemes used to generate the signal carrier and local oscillator are described, as is the fast photodetector used as a mixer for data extraction.

1,037 citations

Journal ArticleDOI
TL;DR: This work demonstrates a miniature 10 GHz radio frequency photonic oscillator characterized with phase noise better than −60 dBc Hz−1 at 10‬GHz, −90 dBc‬Hz+1 at 100‬MHz, and −170‬dBC‬ Frequency Stability, at the level of 10−10 at 1–100‬s integration time.
Abstract: Femtosecond laser-based generation of radio frequency signals has produced astonishing improvements in achievable spectral purity, one of the basic features characterizing the performance of an radio frequency oscillator. Kerr frequency combs hold promise for transforming these lab-scale oscillators to chip-scale level. In this work we demonstrate a miniature 10 GHz radio frequency photonic oscillator characterized with phase noise better than -60 dBc Hz(-1) at 10 Hz, -90 dBc Hz(-1) at 100 Hz and -170 dBc Hz(-1) at 10 MHz. The frequency stability of this device, as represented by Allan deviation measurements, is at the level of 10(-10) at 1-100 s integration time-orders of magnitude better than existing radio frequency photonic devices of similar size, weight and power consumption.

468 citations

Journal ArticleDOI
TL;DR: Recent progress in terahertz wireless communications using telecom-based photonics technologies towards 100 Gbit/s is reviewed.
Abstract: There has been an increasing interest in the application of terahertz (THz) waves to broadband wireless communications. In particular, use of frequencies above 275 GHz is one of the strong concerns among radio scientists and engineers, because these frequency bands have not yet been allocated at specific active services, and there is a possibility to employ extremely large bandwidths for ultra-broadband wireless communications. Introduction of photonics technologies for signal generation, modulation and detection is effective not only to enhance the bandwidth and/or the data rate, but also to combine fiber-optic (wired) and wireless networks. This paper reviews recent progress in THz wireless communications using telecom-based photonics technologies towards 100 Gbit/s.

371 citations

Journal ArticleDOI
TL;DR: This paper will describe how photonic techniques can enable ultrahigh capacity wireless data distribution and transmission using signals at millimeter-wave and TeraHertz frequencies.
Abstract: Optical fibre transmission has enabled greatly increased transmission rates with 10 Gb/s common in local area networks. End users find wireless access highly convenient for mobile communication. However, limited spectrum availability at microwave frequencies results in per-user transmission rates limited to much lower values, e.g., 500 Mb/s for 5-GHz band IEEE 802.11ac. Extending the high data-rate capacity of optical fiber transmission to wireless devices requires greatly increased carrier frequencies. This paper will describe how photonic techniques can enable ultrahigh capacity wireless data distribution and transmission using signals at millimeter-wave and TeraHertz (THz) frequencies.

286 citations