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We demonstrate a THz frequency reference transfer over a 20 km optical fiber with accuracy and stability at the level. Phase information of the THz frequency standard is coherently duplicated onto an optical carrier as an intermediary for exploiting low-loss optical-fiber technology. The transferred information on the optical carrier is retrieved into the THz domain again without phase decoherence...
Asymmetric-dual-grating-gate high-electron-mobility-transistors (ADGG-HEMTs) are expected for on-chip, sensitive, room-temperature operating, high-speed THz detectors. In this paper, we experimentally verify the high-speed response of an ADGG-HEMT by measuring its response to THz pulse generated from an injection-seeded THz-wave parametric generator (is-TPG). From the pulse response waveform of the...
Future, large, multi-terminal HVDC networks are likely to require fast operating circuit breakers to allow stable operation. Several circuit breaker topologies have been developed for fill this purpose [1][2][3]. In this paper, a mechanical active resonant current zero topology DC breaker, capable of interrupting fault current within several milliseconds after tripping, is analysed. In this topology,...
A Large-area charged particle detector for high energy physics experiments has been developed. This detector includes inorganic scintillation crystals and wavelength-shifting fibers. This enables us to detect charged particles with higher position resolution and lower cost than conventional scintillation detectors and gas chambers. It has an effective area of 1 m × 1 m.
A new method using a stopped cosmic-ray beam for the calibration of an electro-magnetic calorimeter which consists of several hundreds of modules has been established. Cosmic muons stop in the calorimeter, and positrons (and electrons) from the muon decays with the maximum energy of 53 MeV are used for the energy calibration. These events could be identified as double pulses observed by a flash ADC...
We examine array configuration and silicon-lens integration of asymmetric-dual-grating-gate high-electron-mobility transistors (A-DGG HEMTs) as plasmonic terahertz detectors in order to enhance their external coupling efficiencies. We demonstrate 4-fold enhancement of the efficiency by an array of four series-connected detectors and 6-fold enhancement by the hyper-hemispherical silicon-lens integration...
We experimentally verify that the low external responsivity of nanostructured asymmetric-dual-grating-gate high-electron-mobility transistors (A-DGG HEMTs) as plasmonic terahertz detectors developed so far is attributed to their low external coupling efficiency. We separately demonstrate (1) 4-fold enhancement of the efficiency by an array of series-connected 4×1 detectors due to the increase in the...
NICT carried out the first calibration of the GPS link between Koganei and Kobe by using GPS, TWSTFT and Clock Transport (CT). We presented the result of the calibration in EFTF 2015. The differential correction of GPS link by GPS, TWSTFT and CT were 102.5, 102.1 and 104.9 ns respectively. The CT result showed a discrepancy of 2 ns. By applying the relativistic effect correction for CT, we confirmed...
DC circuit breakers (DCCB) are critical for reliable operation of High Voltage Direct Current (HVDC) networks and for DC fault isolation in a timely manner in order to allow continued power transmission on the healthy parts of a network following fault clearance. Previous studies show that the speed requirement for DCCBs to clear DC faults, and the critical fault clearing time of individual DCCBs...
Resonant slot-antenna-integrated uni-travelling-carrier photodiodes were developed for enhancing terahertz (THz)-wave output powers while maintaining relatively broad bandwidths. Their output powers were two to three times larger at their peaks than those of a non-resonant bowtie-antenna-integrated device. The output powers were enhanced at frequencies from 900 GHz to 1.6 THz for a narrow-slot device...
High power testing methods for HV DC circuit breaker (DCCB) were investigated. Short circuit breaking tests using quasi-DC current were performed for DCCB based on the current oscillation scheme with active current injection. This DCCB has a high voltage vacuum circuit breaker as the interrupter unit. The tests were performed using two kinds of testing method (power frequency current peak method and...
An HVDC grid will be required to avoid DC voltage collapse and operate the healthy lines continuously, even if a DC fault occurs at the remote end. Rapid fault clearing is essential for DC Circuit Breaker (DCCB) even though the requirement varies depending on DC transmission system configurations, Voltage Source Converter (VSC) design, transmission capacity, and DC reactor connected in series with...
A novel Fermi-level managed barrier diode has been developed for achieving broadband and low-noise terahertz-wave detection. The fabricated quasi-optical module detected signals at frequencies from 200 GHz to 1 THz. The typical voltage sensitivity was 1020 V/W, and the current sensitivity for a 50 Ω load was 4.5 A/W at 300 GHz for a zero-biased condition. Square-law detection with good linearity was...
This paper presents development of high water-permeable dialysis membranes. We proposed the system that does not use dialysis fluid for the implantable micro dialysis treatment and development of such membranes is crucial. We developed micro dialysis system composed by nanoporous membranes and microfluidic channels in our prior work. The membranes were made of nanoporous polyethersulfone (PES), which...
Toward neuroprosthetic technology, it is critical that a simple model system for interaction between brain and electric devices. For this purpose, we developed neurorobot system, Vitroid, equipped with a living neuronal network and a miniature moving robot as a body of the neurorobot. Self-Organization-Map (SOM) was employed as a generator for behavior of Vitroid. SOM was designed to map a high-dimensional...
We observed the avalanche photodiode operation through defect levels at telecom band in Si photonic crystal slow light modulator. Maximum responsivity was 0.71 A/W with 350 avalanche gain. The eye opened at 20 Gbps.
We have been developing a submillimeter resolution and low-cost DOI-PET detector using wavelength shifting fibers (WLSF), scintillating crystal plates and MPPCs (Hamamatsu Photonics). Conventional design of DOI-PET detectors had approximately mm3 of resolution by using some scintillating blocks with a volume of 1 mm3, which detects gamma-ray. They are expensive due to difficulties in processing scintillating...
We have developed a new PID detector consists of clear fibers. PID efficiency was measured with 470 MeV e + beam. As a result, this detector with thickness of 5 cm has the PID efficiency of 95 %.
We are developing the scintillation fiber trackers. This detector is consist of 0.5mm φ scintillation fibers and PPDs. This detector has the doughnut shape with outer diameter of 50cm and inner diameter of 10cm and thickness of 2mm. The position resolution is 70μm There are no ineffective area. And the cost is several million yen.
High Voltage Direct Current (HVDC) transmission has been expanding due to rapid development of power electronics technology and by the need for connection of offshore/remote wind farms and large hydro power generators. An HVDC grid will be required to operate the healthy lines continuously, even if a voltage collapse occurs at the remote end. Rapid fault clearing is essential for DC Circuit Breaker...
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