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Author

Kazuisao Tsuruda

Other affiliations: Osaka University
Bio: Kazuisao Tsuruda is an academic researcher from Rohm. The author has contributed to research in topics: Terahertz radiation & Resonant-tunneling diode. The author has an hindex of 7, co-authored 17 publications receiving 332 citations. Previous affiliations of Kazuisao Tsuruda include Osaka University.

Papers
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Journal ArticleDOI
TL;DR: The results show the potential of photonic crystals for application as terahertz integration platforms and an error-free uncompressed high-definition video transmission by using a photonic-crystal waveguide with a length of as long as 50 cm and up to 28 bends thanks to the low-loss properties.
Abstract: We pursued the extremely low loss of photonic-crystal waveguides composed of a silicon slab with high resistivity (20 kΩ-cm) in the terahertz region. Propagation and bending losses as small as <0.1 dB/cm (0.326–0.331 THz) and 0.2 dB/bend (0.323–0.331 THz), respectively, were achieved in the 0.3-THz band. We also developed 1.5-Gbit/s terahertz links and demonstrated an error-free uncompressed high-definition video transmission by using a photonic-crystal waveguide with a length of as long as 50 cm and up to 28 bends thanks to the low-loss properties. Our results show the potential of photonic crystals for application as terahertz integration platforms.

134 citations

Journal ArticleDOI
TL;DR: In this article, a photonic crystal (PC) cavity was used as a resonator and compact resonant tunneling diodes (RTDs) as signal source and as detector.
Abstract: In this paper, we report on a terahertz (THz) sensing system. Compared to previously reported systems, it has increased system sensitivity and reduced size. Both are achieved by using a photonic crystal (PC) cavity as a resonator and compact resonant tunneling diodes (RTDs) as signal source and as detector. The measured quality factor of the PC cavity is higher than 10,000, and its resonant frequency is 318 GHz. To demonstrate the operation of the refractive index sensing system, dielectric tapes of various thicknesses are attached to the PC cavity and the change in the resonator’s refractive index is measured. The figure of merit of refractive index sensing using the developed system is one order higher than that of previous studies, which used metallic metamaterial resonators. The frequency of the RTD-based source can be swept from 316 to 321 GHz by varying the RTD direct current voltage. This effect is used to realize a compact frequency tunable signal source. Measurements using a commercial signal source and detector are carried out to verify the accuracy of the data obtained using RTDs as a signal source and as a detector.

76 citations

Journal ArticleDOI
TL;DR: An error-free wireless transmission of a 9 Gbit/s on–off keying modulated signal as well as a 4 k video signal is demonstrated using resonant tunnelling diodes as active elements in both the transmitter and the receiver.
Abstract: An error-free wireless transmission of a 9 Gbit/s on–off keying modulated signal as well as a 4 k video signal is demonstrated using resonant tunnelling diodes as active elements in both the transmitter and the receiver. The employed system and the modulation scheme enabling the high data rate are discussed.

70 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe continuous millimeter-wave and terahertz (THz)-wave applications, where telecom-based photonics technologies are efficiently employed to enhance their performance.
Abstract: This paper describes continuous millimeter-wave and terahertz (THz)-wave applications, where telecom-based photonics technologies are efficiently employed to enhance their performance. First, 300-GHz-band wireless communications are described toward real-time error-free transmissions at 50 Gbit/s and beyond. Next, a novel approach to increase a phase measurement sensitivity in THz frequency-domain spectroscopy systems is explained, and a similar technique is successfully applied to the visualization of electric-field radiation and propagation. Finally, as a futuristic study, the manipulation of THz waves with a concept of photonic crystals and its possible applications to platforms in THz integrated systems are presented.

58 citations

Journal ArticleDOI
TL;DR: In this article, circuit models of transmission line elements and of a terahertz resonant tunneling diode (RTD) have been developed for a reliable design of RTD-based oscillator and detector circuits.
Abstract: Circuit models of transmission line elements and of a terahertz resonant tunneling diode (RTD) have been developed. The models allow for a reliable design of RTD-based oscillator and detector circuits. The transmission line elements have been modeled based on electromagnetic field simulations and dc measurements. Their accuracy has been verified through S-parameter measurements. The RTD has been modeled on the basis of dc and S-parameter measurements. The models have been used for the circuit design. A new circuit has been developed that can provide a load impedance that allows for high-output-power oscillators and high-sensitivity detectors. The circuit has been manufactured and measured as an oscillator and as a detector at frequencies around 300 GHz. An excellent agreement between measurement and simulation has been obtained, proving the accuracy of the developed models.

42 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the state-of-the-art technologies on photonics-based terahertz communications are compared with competing technologies based on electronics and free-space optical communications.
Abstract: This Review covers the state-of-the-art technologies on photonics-based terahertz communications, which are compared with competing technologies based on electronics and free-space optical communications. Future prospects and challenges are also discussed. Almost 15 years have passed since the initial demonstrations of terahertz (THz) wireless communications were made using both pulsed and continuous waves. THz technologies are attracting great interest and are expected to meet the ever-increasing demand for high-capacity wireless communications. Here, we review the latest trends in THz communications research, focusing on how photonics technologies have played a key role in the development of first-age THz communication systems. We also provide a comparison with other competitive technologies, such as THz transceivers enabled by electronic devices as well as free-space lightwave communications.

1,238 citations

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate robust terahertz topological valley transport through several sharp bends on the all-silicon chip and achieve real-time transmission of uncompressed 4K high-definition video.
Abstract: The realization of integrated, low-cost and efficient solutions for high-speed, on-chip communication requires terahertz-frequency waveguides and has great potential for information and communication technologies, including sixth-generation (6G) wireless communication, terahertz integrated circuits, and interconnects for intrachip and interchip communication. However, conventional approaches to terahertz waveguiding suffer from sensitivity to defects and sharp bends. Here, building on the topological phase of light, we experimentally demonstrate robust terahertz topological valley transport through several sharp bends on the all-silicon chip. The valley kink states are excellent information carriers owing to their robustness, single-mode propagation and linear dispersion. By leveraging such states, we demonstrate error-free communication through a highly twisted domain wall at an unprecedented data transfer rate (exceeding ten gigabits per second) that enables real-time transmission of uncompressed 4K high-definition video (that is, with a horizontal display resolution of approximately 4,000 pixels). Terahertz communication with topological devices opens a route towards terabit-per-second datalinks that could enable artificial intelligence and cloud-based technologies, including autonomous driving, healthcare, precision manufacturing and holographic communication. Robust terahertz wave transport is demonstrated on a silicon chip using the valley Hall topological phase. Error-free communication is achieved at a data rate of 11 Gbit s−1, enabling real-time transmission of uncompressed 4K high-definition video.

368 citations

Book
01 Jan 2005
TL;DR: In this article, the authors present an overview of the properties of optical dispersion in terms of properties such as: 1.1 Ionicity. 2.2 Specific Heat. 3.4 Microhardness. 4.5 Sound Velocity.
Abstract: Series Preface. Preface. Acknowledgements. 1 Structural Properties. 1.1 Ionicity. 1.2 Elemental Isotopic Abundance and Molecular Weight. 1.3 Crystal Structure and Space Group. 1.4 Lattice Constant and Its Related Parameters. 1.5 Structural Phase Transition. 1.6 Cleavage Plane. 2 Thermal Properties. 2.1 Melting Point and Its Related Parameters. 2.2 Specific Heat. 2.3 Debye Temperature. 2.4 Thermal Expansion Coefficient. 2.5 Thermal Conductivity and Diffusivity. 3 Elastic Properties. 3.1 Elastic Constant. 3.2 Third-Order Elastic Constant. 3.3 Young's Modulus, Poisson's Ratio and Similar. 3.4 Microhardness. 3.5 Sound Velocity. 4 Lattice Dynamic Properties. 4.1 Phonon Dispersion Relation. 4.2 Phonon Frequency. 4.3 Mode Gruneisen Parameter. 4.4 Phonon Deformation Potential. 5 Collective Effects and Some Response Characteristics. 5.1 Piezoelectric and Electromechanical Constants. 5.2 Frohlich Coupling Constant. 6 Energy-Band Structure: Energy-Band Gaps. 6.1 Basic Properties. 6.2 E0-Gap Region. 6.3 Higher-Lying Direct Gap. 6.4 Lowest Indirect Gap. 6.5 Conduction-Valley Energy Separation. 6.6 Direct-Indirect-Gap Transition Pressure. 7 Energy-Band Structure: Effective Masses. 7.1 Electron Effective Mass: G Valley. 7.2 Electron Effective Mass: Satellite Valley. 7.3 Hole Effective Mass. 8 Deformation Potentials. 8.1 Intravalley Deformation Potential: G Point. 8.2 Intravalley Deformation Potential: High-Symmetry Points. 8.3 Intervalley Deformation Potential. 9 Electron Affinity and Schottky Barrier Height. 9.1 Electron Affinity. 9.2 Schottky Barrier Height. 10 Optical Properties. 10.1 Summary of Optical Dispersion Relations. 10.2 The Reststrahlen Region. 10.3 At or Near The Fundamental Absorption Edge. 10.4 The Interband Transition Region. 10.5 Free-Carrier Absorption and Related Phenomena. 11 Elastooptic, Electrooptic and Nonlinear Optical Properties 11.1 Elastooptic Effect. 11.2 Linear Electrooptic Constant. 11.3 Quadratic Electrooptic Constant. 11.4 Franz-Keldysh Effect. 11.5 Nonlinear Optical Constant. 12 Carrier Transport Properties. 12.1 Low-Field Mobility: Electrons. 12.2 Low-Field Mobility: Holes. 12.3 High-Field Transport: Electrons. 12.4 High-Field Transport: Holes. 12.5 Minority-Carrier Transport: Electrons in p-Type Materials. 12.6 Minority-Carrier Transport: Holes in n-Type Materials. 12.7 Impact Ionization Coefficient. Index.

258 citations

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate a quasibound state in the BIC resonance for sensing of a nanometer scale thin analyte deposited on a flexible metasurface.
Abstract: The fingerprint spectral response of several materials with terahertz electromagnetic radiation indicates that terahertz technology is an effective tool for sensing applications. However, sensing few nanometer thin-films of dielectrics with much longer terahertz waves (1 THz = 0.3 mm) is challenging. Here, we demonstrate a quasibound state in the continuum (BIC) resonance for sensing of a nanometer scale thin analyte deposited on a flexible metasurface. The large sensitivity originates from the strong local field confinement of the quasi-BIC Fano resonance state and extremely low absorption loss of a low-index cyclic olefin copolymer substrate. A minimum thickness of 7 nm thin-film of germanium is sensed on the metasurface, which corresponds to a deep subwavelength scale of λ/43 000, where λ is the resonance wavelength. The low-loss, flexible, and large mechanical strength of the quasi-BIC microstructured metamaterial sensor could be an ideal platform for developing ultrasensitive wearable terahertz sensors.

136 citations

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate a quasi-bound state in the BIC resonance for sensing of nanometer scale thin analyte deposited on a flexible metasurface, which is an ideal platform for developing ultra-sensitive wearable terahertz sensors.
Abstract: Fingerprint spectral response of several materials with terahertz electromagnetic radiation indicates that terahertz technology is an effective tool for sensing applications. However, sensing few nanometer thin-film of dielectrics with much longer terahertz waves (1 THz = 0.3 mm) is challenging. Here, we demonstrate a quasi-bound state in the continuum (BIC) resonance for sensing of nanometer scale thin analyte deposited on a flexible metasurface. The large sensitivity originates from strong local field confinement of the quasi-BIC Fano resonance state and extremely low absorption loss of a low-index cyclic olefin copolymer substrate. A minimum thickness of 7 nm thin-film of germanium is sensed on the metasurface, which corresponds to a deep subwavelength length scale of {\lambda}/43000, where {\lambda} is the resonance wavelength. The low-loss, flexible and large mechanical strength of the quasi-BIC micro structured metamaterial sensor could be an ideal platform for developing ultrasensitive wearable terahertz sensors.

135 citations