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A transformerless multicellular dc-dc converter has been newly proposed. The capacitively isolated dc-dc cell converters have been applied to develop the multicellular converter without using high frequency transformers. The high voltage transformation ratio is achieved by the ISOP (Input Series Output Parallel) connection topology of the cell converters and the realization of the highly efficient...
The double taper-type mode convertor for direct bonded GaInAsP/SOI hybrid photonic devices was proposed and the characteristics of the fabricated structure using plasma activated bonding were measured. The calculated and measured results showed the coupling efficiencies of 90% and 75%, respectively.
Bonding conditions and characteristics of N2-plasma activated bonding for GaInAsP/SOI hybrid lasers are explained. SEM and TEM images reveal high quality bonding interface and less damage quantum wells, which are enough to realize hybrid lasers.
Low temperature wafer scale direct bonding technology using plasma activated bonding (PAB) for heterogeneous photonic device integration is reviewed. Nitrogen plasma irradiation in a high vacuum chamber allows tight strength bonding between InP-based and SOI wafers with the bonding temperature of 150°C as well as low damage to GaInAsP quantum wells (QWs). In contrast Argon irradiation cause poor bonding...
An active gate controlled power transfer switch using SiC-MOSFET is proposed to achieve the fault tolerant operation of ISOP (Input Series and Output parallel) multicellular dc-dc converter. The SiC-MOSFET with high temperature capability simplifies the configuration of the protection circuit, and the control of its on-resistance by the active gate control realizes the smooth protection without the...
A monolithically fabricated apodized a-Si:H grating coupler with metal mirror was demonstrated. The minimum groove length for the apodized grating was more than 100 nm and measured coupling efficiency was 70%.
A multicellular ac-dc converter is proposed to realize highly efficient dc distribution system in data centers. The proposed converter consists of the singe-phase full-bridge ac-dc cell converters using ultralow loss GaN (Gallium Nitride) transistors and the non-regulated highly efficient isolated dc-dc cell converters. These cell converters are connected in ISOP (Input Series and Output Parallel)-IPOS...
A vertical trident coupler for 3D optical circuit was demonstrated. This is novel interlayer directional-type coupler between crystalline Si and amorphous-Si:H wire waveguides. The trident structure can manage both easiness of fabrication and high coupling even with relatively thick interlayer distances. In experiment, this trident coupler realized low coupling loss (coupling efficiency) of 0.58dB...
We realized GaInAsP/SOI hybrid Fabry-Pérot (FP) laser with AlInAs-oxide current confinement structure for PICs on a silicon platform. Using hybrid wafers by a plasma activated bonding technique, an AlInAs layer just above GaInAsP quantum wells was oxidized by wet oxidation. A threshold current of 50 mA and an external differential quantum efficiency of 11%/facet were obtained with the unoxidezed stripe...
Highly efficient multi-cell rectifier using low-voltage GaN transistors has been proposed for future 380-V dc distribution in data centers. A 98.8% full-bridge 33- to 48-V ac-dc cell converter has been developed by using GaN transistors. This cell converter maximizes the performance of the multi-cell rectifier based on the series-parallel connection topology of isolated power converters. The potential...
A current-fed ac-dc converter using Gallium Nitride (GaN) power devices has been proposed to realize high power density ISOP (Input Series and Output Parallel)-IPOS (Input Parallel and Output Series) converter-based dc distribution system. The current-fed converter becomes the strong candidate in the ISOP-IPOS converter-based dc distribution system because this system expands the possibility of the...
This paper proposes an example-based method to increase the resolution of a low-resolution image. In the proposed method, we generate example images by a novel view synthesis technique using 3D geometry reconstruction and camera pose estimation from a video or images capturing the same scene. We then increase the resolution by minimizing an energy function by searching for the optimal example from...
Inter-layer coupling between multilayer waveguides was demonstrated using hydrogenated amorphous silicon (a- Si:H) grating couplers with metal mirrors. The fabricated device which has the inter-layer distance of 2 цт successfully showed wider bandwidth compared with uniform grating structure.
Design consideration for the contactless DC connector has been conducted for future high power density 380 V DC distribution system. The power density barrier of 1.2 kW 384 V-192 V inductively-coupled connector based on the LLC resonant converter topology using GaN transistors has been evaluated taking the influences of the circuit configurations, parameters related to the transformer and the semiconductor...
Contactless DC connector has been proposed for high power density 380 V DC power feeding system. A LLC resonant DC-DC converter topology with GaN power transistors and Si-SBDs has been applied to realize high frequency and high efficiency inductively-coupled contactless DC connector. ISOP (input series and output parallel)-IPOS (input parallel and output series) connection topology has been also employed...
In order to realize AlInAs oxidation current confinement structures for III–V/SOI hybrid photonic devices, oxidation condition was investigated. With 4-hours ramp up time and 4-hours ramp down time, 63% of PL intensity was maintained even after the oxidation process at 530°C.
Qualities of Si waveguides after III–V/Si direct bonding process was evaluated, and propagation loss of 4.0 dB/cm was achieved, which is equivalent to the value of waveguides not including direct bonding process.
Contactless DC connector has been proposed for the next generation 380 V DC distribution system in data centers. A LLC resonant DC-DC converter topology with Gallium Nitride (GaN) power transistors has been applied to realize the short-distance inductively-coupled connector. A prototype of a 1.2 kW 384 V–192 V connector has been fabricated under 500 kHz operation. The conversion efficiency of 95%...
A power routing switch using SiC-MOSFET has been developed for the future DC distribution network. The routing switch behaves as an intelligent relay, a circuit breaker and an inrush avoiding circuit. The circuit configuration of the routing switch is based on the non-isolated hard-switching DC-DC converter, and the surge voltage across the SiC-MOSFET is minimized by managing circuit parasitic parameters...
Wavelength trimming for athermal Si slot wavelength filter embedded with BCB using DUV exposure was demonstrated. The total shift of 1.21 nm was obtained after exposing 14 J/cm2 of DUV light without any degradation in athermal and propagation characteristics.
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