Transversely localized low-group-velocity lasing based on self-collimated modes in photonic crystals

Abstract

Transversely localized low-threshold and adjustable lasers based on self-collimation (SC) modes in two-dimensional photonic crystals (PhCs) have been proposed and investigated. The low-threshold property of lasing is from its slow group velocity, while the transverse-localization property is from the flat SC equal-frequency contour that cuts through the whole Brillouin zone. Numerical results have confirmed that SC lasing modes can be controlled by gain distributions and could be stable with certain cavity lengths. The width of the narrowest lasing mode could be smaller than two lattice constants in the transverse direction. The Q-factor of the lasing modes increases linearly with the PhC length, showing potential for ultra-low-threshold lasing. Such lasing modes could be very robust against different directions of PhC edges. The transversely localized SC lasing modes with low group velocity have versatile usages in photonic circuits, e.g. light sources, signal amplifiers and optical switches.