Design and simulation of an electrically pumped Schottky-junction-based plasmonic amplifier

We have investigated an amplifier which operates on surface plasmon polaritons (SPPs). A semiconductor is considered instead of dielectric since its interface with metal can support transverse-magnetic-polarized SPP propagation. A T-shaped cross section for the analyzed waveguide is considered. Metal-semiconductor interface conditions in particular can be regarded as a Schottky junction that has the capability of being pumped electrically. So compensation of propagation loss imposed by metal is possible and beyond that, amplification occurs. This configuration has advantages such as a simple fabrication process and compact size. This scheme has been implemented previously in 3.16, 1.7, and 0.8 mu m for increasing the propagation length of the SPP but here, the free-space wavelength of 1.55 mu m is considered for designing a plasmonic amplifier. This wavelength is selected because this is the most used wavelength in fiber-optic telecommunications due to its ultralow attenuation in silica. However, designing such an amplifier with too many effects that arise in a Schottky junction may be an extremely difficult process. So simplification, which regards essential effects and ignores nonimportant ones, is included. In this work, gold is considered as the metal and n(+) -doped In0.53Ga0.47As as the semiconductor to form a Schottky junction. The semiconductor has a doping concentration of 1 x 10(18) cm(-3). In forward bias of 1.25 V, the gain coefficient of the SPP mode is estimated up to 337 cm(-1) which corresponds to 14.62 dB power gain for a 100 mu m long amplifier. (C) 2015 Optical Society of America