NEC

About: NEC is a company organization based out in Tokyo, Japan. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 33269 authors who have published 57670 publications receiving 835952 citations. The organization is also known as: NEC Corporation & NEC Electronics Corporation.

System and method for efficient content delivery using redirection pages received from the content provider original site and the mirror sites

Abstract: A content delivery system is disclosed. The content delivery system includes a content provider original site configured for communicating with end users over at least one communication network. The content delivery system also includes a memory accessible by the content provider original site for identifying which content has been stored in a mirror site. In response to an end user request for particular content, the content provider original site is capable of accessing the memory, determining if the requested content is stored in a mirror site, and communicating a page to the requesting end user containing a meta-tag for redirecting the requesting end user to load the requested content from the mirror site.

Infrared focal plane array incorporating silicon IC process compatible bolometer

Abstract: A 128/spl times/128 element bolometer infrared image sensor using thin film titanium is proposed. The device is a monolithically integrated structure with a titanium bolometer detector located over a CMOS circuit that reads out the bolometer's signals. By employing a metallic material like titanium and refining the CMOS readout circuit, it is possible to minimize 1/f noise. It is demonstrated that the use of low 1/f noise material will help increase bias current and improve the S/N ratio. Since the fabrication process is silicon-process compatible, costs can be kept low.

Temperature-Dependent Transfer Characteristics of Amorphous InGaZnO4 Thin-Film Transistors

Abstract: The transfer characteristics of amorphous InGaZnO4 thin-film transistors (a-IGZO TFTs) were measured at temperatures ranging from 298 to 523 K in order to analyze the behavior of the above-threshold (ON state) and subthreshold regions. For comparison, the transfer characteristics of a hydrogenated amorphous silicon TFT (a-Si:H TFT) were measured in the same temperature range. We developed a simple analytical model that relates the threshold voltage (Vt) decrease due to increasing temperature to the formation of point defects in a-IGZO. It is well known that the formation of point defects results in the generation of free carriers in oxide semiconductors. Incorporating the analytical model with the experimental transfer characteristics data taken at high temperatures over 423 K, we estimated the formation energy to be approximately 1.05 eV. The Vt decrease because of the generation of point defects is peculiar to a-IGZO TFTs, which is not observed in a-Si:H TFTs. The results for the ON-current activation energy suggested that the density of tail states for a-IGZO is much lower than that for a-Si:H.

Room-temperature CW operation of AlGaInP double-heterostructure visible lasers

Abstract: Room-temperature continuous-wave (CW) operation of (Al0.4Ga0.6)0.5In0.5P/Ga0.5In0.5P/(Al0.4Ga0.6)0.5In0.5P double-heterostructure visible semiconductor lasers has been achieved for the first time. CW operation is obtained up to 50° C. The threshold current at 25° C is mA (4.1 kA/cm2). The lasing wavelength is 689.7 nm.

Si Photonic Wire Waveguide Devices

Abstract: Si photonic wire waveguides are attractive for constructing various optical devices that are extremely small because the waveguides can be bent with extremely small curvatures of less than a few micrometers of bending radius. We have fabricated optical directional couplers with the waveguides and demonstrated their fundamental characteristics. Their coupling length was extremely short, several micrometers, because of strong optical coupling between the waveguide cores. We have also demonstrated wavelength-demultiplexing functions for these devices with a long coupled waveguide. Optical outputs from a device with a 100-mum-long coupled waveguide changed reciprocally with a 20-nm wavelength spacing between the parallel and cross ports. We also demonstrated the operation of ultrasmall optical add-drop multiplexers (OADMs) with Bragg grating reflectors made up of the waveguides. The dropping wavelength bandwidth of the OADMs was less than 0.7 nm, and these dropping wavelengths could be precisely designed by adjusting the grating period. Using the Si photonic wire waveguide, we have also demonstrated thermo-optic switches. Metal thin-film heaters were evaporated onto the branch of a Mach-Zehnder interferometer that incorporated the waveguide to achieve switching operations by thermo-optic effects. In these switching operations, we observed more than 30 dB of extinction ratio, less than 90 mW of switching power, and less than 100 mus of switching speed