Nonrepeating photonic crystal may enable more tunable, reliable semiconductor lasers

Over the past two decades, photonic-crystal surface-emitting lasers (PCSELs) have shown promise as advanced semiconductor lasers for defense and aerospace applications. Typically, these devices use repeating photonic crystal patterns, but new research from electrical and computer engineering professor Kent Choquette's lab introduces a quasi-periodic photonic-crystal surface-emitting laser (QPCSEL) with a nonrepeating pattern. This innovation offers a more versatile and tunable method for creating semiconductor lasers.

Graduate student Erin Raftery led the team in developing a new fabrication technique. Inspired by topologically protected patterns, Raftery integrated a similar patterning method with the group's existing buried dielectric platform. Instead of etching tiny holes vertically through the device like most layered semiconductor materials, Raftery etched a silicon dioxide layer and covered it with epitaxial semiconductor.

This partially periodic structure successfully lased at room temperature, demonstrating the potential for high-performance, fully integrated QPCSELs that are geometry-independent and more flexible to tune.

The primary advantage of this new platform lies in its versatility and uniformity. Currently, researchers can only grow one kind of structure at a time, but this approach allows them to mix and match on the same substrate. This could lead to more reliable and better-performing lasers. The Illinois Grainger engineers are now focusing on developing an electrically injected diode, which would have commercial implications, while continuing to demonstrate the physics behind this innovative laser technology.