Multibeam Lasing Action from Bound States in the Continuum of Photonic Crystal Slab Waveguides

The ability to create optical resonances with high quality-(Q) factors makes photonic crystals (PhCs) an ideal platform for enhanced light-matter interaction, and facilitates the design of efficient active photonic devices at the nanoscale. Here, we utilize the physics of optical bound states in the continuum (BICs) to achieve high-Q resonances in two-dimensional PhC slab waveguides and propose a theoretical design for multibeam lasing action. The proposed PhC slab working at 1300nm supports a quasi-BIC at a wavelength above the diffraction limit. Utilizing Fourier analysis, the optical far-field emitted by the quasi-BIC is investigated and the results show that the zeroth and first diffraction orders are characterized by a topological charge equal to 1. Due to this topological nature of the quasi-BIC, multiple vortex beams are generated into all available diffraction channels. We believe that our multibeam, quantum-dot laser device based on PhC slab waveguides possessing BICs paves a novel way to generate and control laser emission, thus advancing both fundamental research and practical applications in photonics.