Design of a nanogap resonator surface plasmon polariton laser

The inherent tradeoff between the optical mode confinement and the propagation loss due to the high dissipation level of metals has proved to be a significant setback in the design of plasmonic waveguide-based devices. In this Letter, we demonstrate a ring-less nanogap resonator consisting of two straight waveguides with metallic layers and a nanogap between. A finite-difference time-domain simulation of the proposed structure reveals that it exhibits a band-stop and lasing characteristics. The obtained full-width at half-maximum, free spectral range, and Q-factor values are found to be improved as compared to those obtained without a nanogap. Thus, to the best of our knowledge, the new resonator and laser structure can be obtained through the waveguide structure without the ring-shaped resonator.