We demonstrate and analyze an upconversion blue fiber laser pumped by two wavelengths. Lasing at 0.48 mum with very low pump threshold power is obtained from a Tm-doped fluorozirconate fiber that is counterpropagating pumped by 1.21- and 0.649-mum light. We employed a rate-equation analysis using parameters obtained by fitting to the experimental data to predict the 0.48-mum output characteristics as a function of fiber length and output reflectivity.
An advanced power system in package (SiP) for voltage regulators is presented; it offers the world's lowest power dissipation of 4.4 W at 1 MHz, with an output voltage of 1.3 V and an output current of 25 A. Its package resistance is 88% lower due to using Cu leads for the bonding, which reduces the spreading resistance of the MOSFET. The diode loss is 43% lower due to using a Schottky barrier diode incorporated into the low-side MOSFET. The thermal resistance is also 43% lower due to using a large topside Cu lead.
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