Europium doped alkaline earth fluoride [Eu:AEF 2 (AE = Ca, Sr, Ba)] nanoparticles were synthesized and systematically incorporated into the core of modified chemical vapor deposition (MCVD)-derived silicabased preforms by solution doping. The resulting preforms were examined to determine the impact of the nanoparticles chemistry on the spectroscopic behavior of the glass. The dominant existence of Eu 3+ was demonstrated in all preforms, which is in contrast to conventional solution doped preforms employing dissolved europium salts where Eu 2+ is primarily observed. Raman spectroscopy and fluorescence lifetime measurements indicated that the nanoparticles composition is effective in controlling, at a local chemical and structural level, the spectroscopic properties of active dopants in optical fiber glasses. Further, there is a systematic and marked increase in radiative lifetime, τ, of the Eu 3+ emission that follows the cationic mass; τ Ca < τ Sr < τ Ba with the BaF 2-derived sample yielding a 37% lengthening of the lifetime over the CaF 2-derived one. Such nanoscale control of what otherwise is silica glass could be useful for realizing property-enhanced and tailored spectroscopic performance from otherwise "standard" materials, e.g., vaporderived silica, in next generation optical fibers.
Polymer-stabilized blue-phase liquid crystal (BPLC) comprising fluorinated compounds with high resistivity and photochemical stability is demonstrated. The Kerr constant, driving voltage, and response time of this BPLC are measured using an in-plane switching liquid crystal cell. At 20 °C, the measured total response time is faster than 0.7 ms and Kerr constant is 2 nm/V2. This fluorinated BPLC material is a promising candidate for next-generation photonic and display devices, because it can be used in active matrix addressed devices.
The issue of metal interconnect resistance becomes increasingly critical as the power MOSFET technology continues to advance. This paper introduces a three-dimensional finite element analysis (FEA) approach to model the influence of source metal on the performance of power MOSFETs with ultra low on-resistance. Various source metal interconnection designs for two commercial discrete packages, the D2PAK and DirectFET, are studied extensively using the newly developed FEA model. It is found that the number and location of wirebonds or solder pads as well as the interconnect layout all have considerable impact on the total on-resistance of a power MOSFET. Furthermore, the metal interconnect resistance imposes another limit on the lowest RDS(On) that can be practically achieved on power MOSFETs even in light of the ever-decreasing silicon-contributed specific on-resistance.
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