Physics Education Centre

Over the past decade, photonic crystal surface-emitting lasers (PCSELs) have emerged as a compelling alternative to conventional vertical cavity surface-emitting lasers (VCSELs), owing to their superior beam quality and scalable output power. Watt-class PCSELs have already been demonstrated and are now commercially available for applications in LiDAR and telecommunications. However, all existing PCSELs are fabricated using conventional top-down approaches, where structural damage from the dry etching process is unavoidable.

In this project, we aim to demonstrate PCSELs constructed from vertically-standing III-V semiconductor nanowires as the fundamental building blocks. Unlike traditional PCSELs that depend on top-down etching to define the laser cavity, nanowires naturally form atomically smooth sidewall facets during the epitaxial growth process, effectively eliminating scattering losses due to surface roughness. Furthermore, each nanowire simultaneously functions as both the optical cavity and gain medium, enabling optimal coupling between light emission and the lasing cavity. We will also explore more advanced nanowire-based PCSEL designs, including hetero-lattice PCSELs with enhanced in-plane optical feedback and topological PCSELs.

This research project can be tailored to suit students of the following type(s)