A Fano resonance is a general phenomenon occurring in Nature whenever a continuum of states interacts with a single, discrete state. It was suggested that such a resonance can be used to realize an ultra-small laser with remarkable properties, which has led to subsequent analysis and experimental realization.
The laser is realized in a photonic crystal membrane with embedded quantum dots for active material. The Fano resonance occurs due to the interaction of the optical mode in the nanocavity and the continuum of waveguide modes, which leads to a strongly resonant suppression of transmission, effectively forming a narrowband and highly dispersive laser mirror.
Simulations and experiments have demonstrated some remarkable properties of this laser, including the first reported case of laser self-pulsing on a microscopic scale, consistent single-mode lasing and a theoretical frequency modulation bandwidth orders of magnitude larger than conventional semiconductor lasers.
The reflection spectrum may be modified by placing additional air holes in the waveguide below the nanocavity, which can yield asymmetric or inverted spectra compared to the conventional Lorentzian shape. If the waveguide is completely blocked, the in-plane out-coupling is mediated entirely through the nanocavity, yielding a novel laser structure, which may potentially combine the desirable qualities of both the Fano laser and the conventional line-defect lasers.
This modified structure is entirely unexplored as of yet, so the project provides the opportunity to work on a novel structure based on bridging the gap between two separate laser designs with different useful qualities, in order to investigate new physics and design light sources for the photonic integrated circuits of the future.
The project can be tailored to cover a suitable combination of theory, numerical modelling, and experimental work, depending on the interests and competencies of the student(s).