| The behaviour of surface plasmon polaritons (SPPs) in nanoscale geometries is studied using numerical methods supported by theory and experiment. First, we derive the behaviour of SPPs at graded metal-dielectric interfaces, including dispersion relations, field profiles, propagation velocities, losses, and cutoff wavelength. Numerical simulations show excellent agreement with analytic solutions. In the second part of the thesis we design hybrid vanadium dioxide-plasmonic based absorption switches. The switches are designed and optimized using optical, electrical and thermal simulations. 5 µm switch designs have extinction ratios exceeding 30 dB and require powers of 10 mW. A switch is fabricated based on the proposed design. A 7 µm experimental switch reaches 16.4 dB of extinction and requires 64 mW of power, making it one of the most efficient optical switches ever demonstrated in terms of extinction and power consumption. Numerical simulations predict experimental results with a high degree of accuracy. |
