Using the formalism of mode overlap, a theoretical analysis of optically pumped fiber laser amplifiers and oscillators is developed. The concept of normalized overlap coefficients is introduced to account for the effects of the transverse structure of the interacting signal and pump modes on the device characteristics. Simple and accurate closed-form expressions are derived for the gain of fiber amplifiers and the threshold and energy conversion efficiency of fiber laser oscillators in terms of the fiber and laser material parameters and the pump and signal modes. When applied to step-index Nd:YAG fiber lasers, this study predicts optimum fundamental mode oscillation in fibers with a V number of 5-25 with submilliwatt thresholds and nearly quantum-limited conversion efficiencies.

A conformal TMS sensor array with improved thermal sensitivity and dimensional stability was investigated for real-time skin temperature monitoring. This fixed-geometry, body-conforming array of thermal sensors allows fast and accurate characterization of two-dimensional temperature distributions over large surface areas. The prototype TMS demonstrates significant advantages over clinical probes for characterizing skin temperature distributions during hyperthermia treatments of superficial tissue disease.

In this paper, the unsteady state heat transfer equations with time dependent boundary conditions are coupled with a two-dimensional finite element method to predict the work-roll temperature distribution during the continuous hot slab rolling process. To achieve an accurate temperature field, the effects of various factors including the thermal relationship of the work-roll and the metal slab, the idling work-roll revolutions, the rolling speed, the slab/roll interfacial heat transfer coefficient, and the magnitude of the thickness reduction of the slab at each deformation pass are taken into account. Comparisons between the predicted and published experimental results are used to illustrate the validity of the mathematical model.

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