Semiconductor micro-ring and micro-disk lasers for all-optical switching

We review and compare recent results on the design and fabrication of semiconductor microring and microdisk lasers for applications in all-optical switching and signal processing. The design of the optical cavities will be analyzed in detail with a strong emphasis on the evaluation of the various loss mechanisms. Both lithographic and etching technologies were thoroughly optimized to ensure high-resolution patterning and deep and vertical waveguide sidewalls. The majority of the fabricated devices exhibited continuous wave operation down to 7 μm and strong unidirectional bistability down to device footprints as small as 30 μm. While both microdisks and microrings show similar behaviour for medium radii (30-60 μm), in smaller devices the microdisk geometry shows much lower losses and better performance.