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Both theoretical and simulation approaches were used to obtain the thermal power and temperature distribution in phosphor-converted white LEDs (pc-WLEDs) using a remote-dome phosphor package (RDPP). Different material and geometric parameters were systematically and thoroughly studied. An experiment was performed to measure the temperature distribution in an RDPP pc-WLED, which confirmed the simulation results. Given practical limitations of the material parameters, the most feasible method to reduce the phosphor temperature is to extend the dome radius and the thickness of the phosphor region.

Two experimental configurations, an imaging system and a confocal system, are constructed to measure the spectral reflectance of human irises in vivo. The light from a white light-emitting diode (LED) is focused on the iris and the reflected light is measured by a spectrometer. A flat plate coated with barium sulphate (Ba2SO4) with reflectance 0.99 for visible light is used as a reference to calibrate the system. Samples of gray-blue and black-brown eyes are measured to compare the performance of the two systems. The differences between the reflectance spectra of the two systems show that Fresnel reflection from the interface between air and cornea is the dominating effect. The spatial filtering characteristic of the confocal system provides a nice capability in eliminating the contribution of cornea reflectance. [ABSTRACT FROM PUBLISHER]

Double patterning technology (DPT), in which a dense layout pattern is decomposed into two separate masks to relax its pitch, is the most popular lithography solution for the sub-22 nm node to enhance pattern printability. Previous work focused on stitch insertion to improve the decomposition success rate. However, there exist native conflicts (NCs) which cannot be resolved by any kind of stitch insertion. A design with NCs is not DPT-compliant and may fail the decomposition, resulting in design for manufacturability redesign and longer design cycles. In this paper, we give a sufficient condition for the NC existence and propose a geometry-based method for NC prediction to develop an early-stage analyzer for DPT decomposability checking. Then, a wire perturbation algorithm is presented to fix as many NCs in the layout as possible. The algorithm is based on iterative 1-D compaction and can easily be embedded into existing industrial compaction systems. The algorithm is then further applied to further reduce the number of stitches required for the decomposition process. Experimental results show that the proposed algorithm can significantly reduce the number of NCs by an average of 85% and reduce the number of stitches by an average of 39%, which may effectively increase the decomposition success rate for the next stage. [ABSTRACT FROM PUBLISHER]

Given a set of pins and a set of obstacles on a plane, an obstacle-avoiding rectilinear Steiner minimal tree (OARSMT) connects these pins, possibly through some additional points (called the Steiner points), and avoids running through any obstacle to construct a tree with a minimal total wirelength. The OARSMT problem becomes more important than ever for modern nanometer IC designs which need to consider numerous routing obstacles incurred from power networks, prerouted nets, IP blocks, feature patterns for manufacturability improvement, antenna jumpers for reliability enhancement, etc. Consequently, the OARSMT problem has received dramatically increasing attention recently. Nevertheless, considering obstacles significantly increases the problem complexity, and thus, most previous works suffer from either poor quality or expensive running time. Based on the obstacle-avoiding spanning graph, this paper presents an efficient algorithm with some theoretical optimality guarantees for the OARSMT construction. Unlike previous heuristics, our algorithm guarantees to find an optimal OARSMT for any two-pin net and many higher pin nets. Extensive experiments show that our algorithm results in significantly shorter wirelengths than all state-of-the-art works. [ABSTRACT FROM AUTHOR]