Design of 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.