I like the summary of the LinkedIn Apple employee that Heinz44 posted.

A semiconductor professional with extensive experience on process development and integration, device design and characterization for a wide range of III-V devices including VCSEL, GaAs-based high-power lasers, photo detectors detectors, InP-based photonics IC's.

Significant experience on transferring products from R&D stages to high-volume manufacturing stages

Solid device physics background on lasers and detectors. Extensive experience on a wide range of semiconductor materials covering from UV to LWIR (20um) wavelength range including GaAs, GaN, InP, InAs, InSb, GaSb etc.

Extensive process integration and development experience in both semiconductor foundry company and integrated optical component company