Adult-onset epilepsy in focal cortical dysplasia of Taylor type.

Focal cortical dysplasia of Taylor type (FCDT) usually presents with seizures at an early age, whereas adult onset of epilepsy is uncommon. We reviewed the medical records of 213 patients with FCDT. In 21 patients (10%), age at seizure onset ranged from 18 to 55 years (mean 25.3). The outcome of seizures in patients with FCDT and adult-onset epilepsy seems favorable vs childhood-onset seizures.

Gallium arsenide laser-array-on-silicon package.

A monolithic array of AlGaAs lasers has been packaged together with an array of fiber lightguides on a substrate of silicon. The components have been optimized for maximum lightguide output radiance consistent with reliable cw laser operation. Coupling efficiencies up to 80% have been achieved between laser and lightguide. Output powers up to 70 mW cw have been observed from a 50-microm core diameter lightguide of 0.15 numerical aperture. Eight-device array multispot packages have been fabricated with 10 mW/spot, limited by laser quality and thermoelectric cooler capacity. Fabrication tolerances and device electrical and optical crosstalk are discussed.

Thermal performance and limitations of silicon-substrate packaged GaAs laser arrays.

Thermal resistance and crosstalk have been investigated for a source package consisting of a monolithic, multilaser heterojunction array mounted on a single crystalline silicon substrate, which is in turn laminated to a copper heatsink. Models for 2-D and 3-D heat spreading are used to calculate the heat flow distribution and to obtain upper and lower bounds for both resistance of single devices and crosstalk in arrays. Results for experimental five-laser arrays are shown to fall within these limits. Active cooling is required to maintain junctions at safe operating temperatures prerequisite to stable, long-lived operation.