Dissertation Talk: Minimally Perturbative Electrical Injection for Scalable Photonic Crystal Surface-Emitting Lasers

Event details Date: Monday, August 3, 2026 Time: 2:00 PM to 2:00 PM Location: In Person: Cory 299 Type: Sports Audience: Faculty,Students About this event The rapid growth of artificial intelligence has driven a corresponding demand for high-bandwidth optical interconnects, making optoelectronics increasingly important for communication, computing, and emerging photonic systems. Semiconductor lasers are central to these applications as compact and efficient sources of coherent light, but scaling their aperture while maintaining stable single-mode operation has remained a fundamental challenge. The Berkeley Surface-Emitting Laser (BerkSEL) platform overcomes this limitation using an open-Dirac photonic crystal cavity that supports a scale-invariant mode. This scale-invariant behavior, however, relies on precise photonic band engineering and strong refractive-index contrast, making it challenging to introduce electrical carriers across the large aperture without perturbing the optical integrity of the cavity. This thesis addresses this challenge by developing a minimally perturbative electrical injection scheme for extended nanophotonic apertures. We first demonstrate a monolithic quasi-suspended photonic crystal architecture in which a periodic array of subwavelength nano-posts provides electrical and thermal connection between the nanophotonic aperture and the epitaxial substrate. The nano-posts are strategically placed at the electromagnetic field nodes to enable distributed carrier injection across hundreds of unit cells while minimizing perturbation to the optical mode. Coupled optical, electrical, and thermal modeling is used to investigate the effects of nano-post geometry and uniformity, followed by the experimental demonstration of room-temperature electrically pumped lasing at telecommunication wavelengths. Building on this approach, we develop electrical pumping architectures for BerkSEL based on substrate-compatible open-Dirac cavities and several current-injection and current-spreading schemes. Together, these results establish an optical-electrical co-design framework in which carrier delivery, optical confinement, thermal transport, and photonic band structure... Official event details: https://events.berkeley.edu/eecs/event/324897-dissertation-talk-minimally-perturbative