Mode field diameter and nonlinear properties of air-core nanowires

Exact solutions of Maxwell's equations describing the lightwave through 3-layer-structured cylindrical waveguide are obtained and the mode field diameter and nonlinear coefficient of air-core nanowires (ACNWs) are numerically calculated. The simulation results show that ACNWs offer some unique optical properties, such as tight field confining ability and extremely high nonlinearity. At a certain wavelength and air core radius, we optimize the waveguide design to maximize the nonlinear coefficient and minimize the mode field diameter. Our results show that the ACNWs may be powerful potential tools for novel micro-photonic devices in the near future.

Silver nanocrystals modified microstructured polymer optical fibres for chemical and optical sensing

In-fibre chemical and optical sensors based on silver nanocrystals modified microstructured polymer optical fibres (MPOFs) were demonstrated. The silver nanocrystals modified MPOFs were formed by direct chemical reduction of silver ammonia complex ions on the templates of array holes in the microstructure polymer optical fibres. The nanotube-like and nanoisland-like Ag-modified MPOFs could be obtained by adjusting the conditions of Ag-formation in the air holes of MPOFs. SEM images showed that the higher concentration of the reaction solution (silver ammonia 0.5 mol/L, glucose 0.25 mol/L), gave rise to a tubular silver layer in MPOF, while the lower concentration (silver ammonia 0.1 M, glucose 0.05 M) produced an island-like Ag nanocrystal modified MPOF. The tubular Ag-MPOF composite fibre was conductive and could be directly used as array electrodes in electrochemical analyses. It displayed high electrochemical activity on sensing nitrate or nitrite ions. The enhanced fluorescence of dye molecules was observed when the island-like Ag-modified MPOF was inserted into a fluorescent dye solution. (C) 2007 Elsevier B.V. All rights reserved.

Liquid-filled microstructured polymer fibers as monolithic liquid-core array fibers

Liquid-filled microstructured polymer optical fibers (MPOFs) as monolithic liquid-core array fiber are proposed and prepared by injecting high-refractive-index liquid into the holes array of the MPOFs. One example for potential applications is demonstrated as a new kind of coherent imaging fiber. It provides great potential for applications in chemical sensing, biosensors, and endoscopy, particularly in bifunctional detection. (C) 2009 Optical Society of America

Design for an IO block array in a tile-based FPGA

A design for an IO block array in a tile-based FPGA is presented.Corresponding with the characteristics of the FPGA, each IO cell is composed of a signal path, local routing pool and configurable input/output buffers.Shared programmable registers in the signal path can be configured for the function of JTAG, without specific boundary scan registers/latches, saving layout area.The local routing pool increases the flexibility of routing and the routability of the whole FPGA.An auxiliary power supply is adopted to increase the performance of the IO buffers at different configured IO standards.The organization of the IO block array is described in an architecture description file, from which the array layout can be accomplished through use of an automated layout assembly tool.This design strategy facilitates the design of FPGAs with different capacities or architectures in an FPGA family series.The bond-out schemes of the same FPGA chip in different packages are also considered.The layout is based on SMIC 0.13μm logic 1P8M salicide 1.2/2.5 V CMOS technology.Our performance is comparable with commercial SRAM-based FPGAs which use a similar process.

4-W single transverse mode Yb3+-doped fiber laser pumped by 915-nm laser diode array

A cladding-pumped ytterbium-doped fiber laser is described in this letter. Using unusual pumping source with 915-nm wavelength, slope efficiency up to 75% with respect to absorbed input power and output power is obtained, a maximum output power of 4.006 W with fundamental mode is measured.

AIN Monolithic Microchannel Cooled Heatsink for High Power Laser Diode Array

A novel AIN monolithic microchannel cooled heatsink for high power laser diode array is introduced.The high power stack laser diode array with an AIN monolithic microchannel heatsink is fabricated and tested.The thermal impedance of a 10 stack laser diode array is 0.121℃/W.The pitch between two adjacent bars is 1.17mm.The power level of 611W is achieved under the 20% duty factor condition at an emission wavelength around 808nm.

Fiber Optic Coupling of CW Linear Laser Diode Array

Based on a set of microoptics the output radiation from a continuous wave (CW) linear laser diode array is coupled into a multi-mode optical fiber of 400 ptm diameter. The CW linear laser diode array is a 1 cm laser diode bar with 19 stripes with 100 fxm aperture spaced on 500 (xm centers. The coupling system contains packaged laser diode bar, fast axis collimator, slow axis collimation array, beam transformation system and focusing system. The high brightness, high power density and single fiber output of a laser diode bar is achieved. The coupling efficiency is 65% and the power density is up to 1.03 * 10~4 W/cm~2.

Array for 980nm Vertical Cavity Surface Emitting Diodes and Detectors

Both the vertical cavity surface emitting diodes and detectors are fabricated by using the epitaxial wafer with resonant cavity structure. Their characteristics are analyzed. The light emitters have high spectral purity of 4.8nm and high electroluminescence intensity of 0.7mW while injection current is 50mA. A 1*16 array of surface emitting light device is tested on line by probes and then used for module. The light detectors have wavelength selectivity and space selectivity. The required difference in input mirror reflectivity between emitters and detectors can easily be achieved though varying the numbers of top DBR period by etching.

Fiber Coupling of Laser Diode Bar to Multimode Fiber Array

A piece of multimode optical fiber with a low numerical aperture (NA) is used as an inexpensive microlens to collimate the output radiation of a laser diode bar in the high numerical aperture (NA) direction. The emissions of the laser diode bar are coupled into multimode fiber array. The radiation from individual ones of emitter regions is optically coupled into individual ones of fiber array. Total coupling efficiency and fiber output power are 75% and 15W, respectively.

Monolithic Integration DFB Laser Array by Angling Active Stripe and Using Thin-Film Stripe Heater

国家863计划

Mode theory and analysis of planar array waveguides

Bloch modes can be excited in planar array due to its periodic lateral refractive index. The power coupled into each eigenmode of the array waveguides is calculated through the overlap integrals of the input field with the eigenmode fields of the coupled infinite array waveguides projected onto the x-axis. Low losses can be obtained if the transition from the array to the free propagation region is adiabatic. Due to the finite resolution of lithographic process the gap between the waveguides will stop abruptly, however, when the waveguides come into too close together. Calculation results show that losses will occur at this discontinuity, which are dependent on the ratio of the gap between the waveguides and grating pitch and on the confinement of field in the array waveguides. Tapered waveguides and low index contrast between the core and cladding layers can lower the transmitted losses.