Ultra-large Area Research Articles

SEGMENTED-CORE SINGLE MODE OPTICAL FIBER WITH ULTRA-LARGE-EFFECTIVE-AREA, LOW DISPERSION SLOPE AND FLATTENED DISPERSION FOR DWDM OPTICAL COMMUNICATION SYSTEMS

In this paper we present designs of flbers having non-zero positive, non-zero negative and near-zero ultra-∞attened dispersion with small dispersion slope and ultra-large efiective area over a wide spectral range. The designs consist of a concentric multilayer segmented core followed by a trench assisted cladding and a thin secondary core. The central segmented core helps in maintaining desired dispersion over a wide range of wavelength. The second core of the flber helps in achieving ultra-large efiective area and trench assisted cladding reduces the bending loss. The designs of the flber have been analyzed by using the transfer matrix method. For positive non-zero dispersion ∞attened flber we have optimized dispersion near +4:5ps/km/nm in the wavelength range 1.46{1.65m. Maximum value of dispersion slope of the flber in above mentioned wavelength range is 0.026ps/km/nm 2 . In the design of negative non-zero dispersion ∞attened flber, dispersion has been achieved near i6ps/km/nm in the spectral range of 1.33{1.56m and maximum value of dispersion slope is 0.048ps/km/nm 2 . Dispersion and dispersion slope of near zero dispersion ∞attened flber lie in the range (0.0039{ 0.520)ps/km/nm and ((0.0004){(0.0365))ps/km/nm 2 respectively in the spectral range of 1.460{1.625m. The near zero dispersion ∞attened flber has an ultra-high efiective area ranging from 114m 2 to 325.95m 2 in the aforementioned wavelength range, which covers the entire S+C+L-band. These values of mode area are noticeably higher than those reported in literature for ∞attened dispersion flbers with large mode area. Designed flber shows very small bending loss. We report breakthrough in the mode area of the single mode optical flber with ultra ∞attened dispersion and low dispersion slope.

Optoelectronic tweezers integrated with lensfree holographic microscopy for wide-field interactive cell and particle manipulation on a chip.

We demonstrate an optoelectronic tweezer (OET) coupled to a lensfree holographic microscope for real-time interactive manipulation of cells and micro-particles over a large field-of-view (FOV). This integrated platform can record the holographic images of cells and particles over the entire active area of a CCD sensor array, perform digital image reconstruction to identify target cells, dynamically track the positions of cells and particles, and project light beams to trigger light-induced dielectrophoretic forces to pattern and sort cells on a chip. OET technology has been previously shown to be capable of performing parallel single cell manipulation over a large area. However, its throughput has been bottlenecked by the number of cells that can be imaged within the limited FOV of a conventional microscope objective lens. Integrating lensfree holographic imaging with OET solves this fundamental FOV barrier, while also creating a compact on-chip cell/particle manipulation platform. Using this unique platform, we have successfully demonstrated real-time interactive manipulation of thousands of single cells and micro-particles over an ultra-large area of e.g., 240 mm(2) (i.e. 17.96 mm × 13.52 mm).

A Survey on the Siltation Motoring Database for Ultra-Large Reservoir Area

Based on the data source of CBERS-02B satellite, approaches such as computer density segmentation and statistical processing can be used first in combination with the research of water front monitoring in the ultra-large reservoir area, and then with Gray relevancy grade on water-depth monitoring. In line with the above, a suitable set of research plans on the siltation monitoring have been made including technical route and test methods.

Polarization multiplexed 16QAM transmission employing modified digital back-propagation

We experimentally demonstrate performance enhancements enabled by weighted digital back propagation method for 28 Gbaud PM-16QAM transmission systems, over a 250 km ultra-large area fibre, using only one back-propagation step for the entire link, enabling up to 3 dB improvement in power tolerance with respect to linear compensation only. We observe that this is roughly the same improvement that can be obtained with the conventional, computationally heavy, non-weighted digital back propagation compensation with one step per span. As a further benchmark, we analyze performance improvement as a function of number of steps, and show that the performance improvement saturates at approximately 20 steps per span, at which a 5 dB improvement in power tolerance is obtained with respect to linear compensation only. Furthermore, we show that coarse-step self-phase modulation compensation is inefficient in wavelength division multiplexed transmission.

Semi-guiding high-aspect-ratio core (SHARC) fiber providing single-mode operation and an ultra-large core area in a compact coilable package

A new class of optical fiber is presented that departs from the circular-core symmetry common to conventional fibers. By using a high-aspect-ratio (~30:1) rectangular core, the mode area can be significantly expanded well beyond 10,000 μm2. Moreover, by also specifying a very small refractive-index step at the narrow core edges, the core becomes "semi-guiding," i.e. it guides in the narrow dimension and is effectively un-guiding in the wide mm-scale dimension. The mode dependence of the resulting Fresnel leakage loss in the wide dimension strongly favors the fundamental mode, promoting single-mode operation. Since the modal loss ratios are independent of mode area, this core structure offers nearly unlimited scalability. The implications of using such a fiber in fiber laser and amplifier systems are also discussed.

Electron emission from ultralarge area metal-oxide-semiconductor electron emitters

Ultralarge metal-oxide-semiconductor (MOS) devices with an active oxide area of 1cm2 have been fabricated for use as electron emitters. The MOS structures consist of a Si substrate, a SiO2 tunnel barrier (∼5nm), a Ti wetting layer (3–10Å), and a Au top layer (5–60nm). Electron emission from the Au metal layer to vacuum is realized from these devices by applying bias voltages larger than the work function of the Au layer. The emission is characterized for Au layers with thicknesses ranging from 5to60nm nominally. The emission efficiency changes from close to 10−6 to 10−10. The Ti wetting layer is varied from 3to10Å which changes the emission efficiency by more than one order of magnitude. The apparent mean free path of ∼5eV electrons in Au is found to be 52Å. Deposition of Cs on the Au film increased the electron emission efficiency to 4.3% at 4V by lowering the work function. Electron emission under high pressures (up to 2bars) of Ar was observed.

PICO-LON project for WIMPs search

Highly segmented inorganic crystal has been shown to have good performance for dark matter search. The energy resolution of ultra thin and large area NaI(T1) scintillator has been developed. The estimated sensitivity for spin-dependent excitation of 127I was discussed. The recent status of low background measurement at Oto Cosmo Observatory is reported

Ultralarge area MOS tunnel devices for electron emission

A comparative analysis of metal-oxide-semiconductor (MOS) capacitors by capacitance-voltage $(C\text{\ensuremath{-}}V)$ and current-voltage $(I\text{\ensuremath{-}}V)$ characteristics has been employed to characterize the thickness variations of the oxide on different length scales. Ultralarge area $(1\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2})$ ultrathin ($\ensuremath{\sim}5\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ oxide) MOS capacitors have been fabricated to investigate their functionality and the variations in oxide thickness, with the use as future electron emission devices as the goal. $I\text{\ensuremath{-}}V$ characteristics show very low leakage current and excellent agreement to the Fowler-Nordheim expression for the current density. Oxide thicknesses have been extracted by fitting a model based on Fermi-Dirac statistics to the $C\text{\ensuremath{-}}V$ characteristics. By plotting $I\text{\ensuremath{-}}V$ characteristics in a Fowler plot, a measure of the thickness of the oxide can be extracted from the tunnel current. These apparent thicknesses show a high degree of correlation to thicknesses extracted from $C\text{\ensuremath{-}}V$ characteristics on the same MOS capacitors, but are systematically lower in value. This offset between the thicknesses obtained by $C\text{\ensuremath{-}}V$ characteristics and $I\text{\ensuremath{-}}V$ characteristics is explained by an inherent variation of the oxide thickness. Comparison of MOS capacitors with different oxide areas ranging from $1\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}10\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}{\mathrm{m}}^{2}$, using the slope from Fowler-Nordheim plots of the $I\text{\ensuremath{-}}V$ characteristics as a measure of the oxide thickness, points toward two length scales of oxide thickness variations being $\ensuremath{\sim}1\phantom{\rule{0.3em}{0ex}}\mathrm{cm}$ and $\ensuremath{\sim}10\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$, respectively.

Ultra-Large Area RF Plasma Sources Employing Multiple Low-Inductance Internal-Antenna Modules for Flat Panel Display Processing

Plasma-generation and control technologies for meters-scale ultra-large-area RF plasma sources have been developed with multiple low-inductance antenna (LIA) modules, as a promising candidate of ultra-large area and high-density (1011-1012 cm-3) plasma sources for next-generation large-area processing. The present technologies are based on principle of multiple operation and integrated control of LIA modules, which enables effective control of power deposition profiles and hence the plasma uniformity over meters-scale large area for processing. This paper presents issues in designing ultra-large-area plasma sources to demonstrate feasibility of the uniform sources with 3m x 3m scales to meet requirements in the next-generation processes.

Research frontier on new materials and concepts for hydrogen storage

In the past two years, a number of research projects on new materials and concepts for hydrogen storage were started at US universities and national laboratories, as well as industrial entities. These projects are sponsored by the US Department of Energy (DOE), with the primary goal of discovering and developing new materials that have sufficient hydrogen storage capacity for future hydrogen-fueled vehicles. Four areas are being explored: (1) new materials that have ultra large adsorption area; (2) adsorption surfaces with highly active sites; (3) new adsorption/desorption mechanisms; and (4) high hydrogen-content compounds. This article reviews these projects with the authors’ understanding of hydrogen storage fundamentals, and hopes to provide insights into this research frontier.