Long-range surface plasmon single-mode laser concepts

Abstract

Near infrared single-mode lasers based on long-range surface plasmon-polariton waveguides and step-in-width Bragg gratings implemented with thin Ag stripes are proposed. The gain medium assumed is a polymer (poly(methylmethacrylate)) doped with organic laser dye molecules (IR-140). Three cavity resonator configurations have been investigated based on distributed feedback or distributed Bragg reflectors. Narrow line-width single-mode lasing is guaranteed by appropriately trading-off the length of the active region against the threshold lasing gain and designing gratings of sufficiently narrow bandwidth. Laser wavelength tuning through thermal modulation of the polymer refractive index by injecting current along the Ag gratings is briefly described.