Laser characteristics with ultimate-small modal volume in photonic crystal slab point-shift nanolasers

We recently reported the laser operation of a nanocavity consisting only of a shift in two of the lattice points in a GaInAsP photonic crystal slab. In this study, we investigated the laser characteristics in detail. For lithographic tuning, three different modes were observed, and good agreement between the experimental results and theoretical calculations performed using the finite-difference time-domain method was obtained. These results suggest that the fundamental mode has a modal volume of $0.02\mu {\mathrm{m}}^3\sim 2.1{(\lambda ∕2n)}^3$ , which is the smallest in any kind of laser. Such an ultrasmall modal volume will ensure efficient electron-photon coupling.