Laser stimulated electron field emission at the plasmon-resonant wavelength

Laser stimulated electron field emission from a sharp gold tip under continuous-wave (cw) laser irradiation at the plasmon-resonant wavelength are investigated. A gold-coated tungsten emitter with a tip radius of 100 nm which has the plasmon resonant wavelength at 530 nm is used. I-V characteristics of the tip under laser irradiations at 442, 532, and 633 nm were measured. TE-polarized 532-nm irradiation shows the maximum current enhancement despite its smaller photon energy and intensity compared with the irradiation at 442 nm. The current enhancement factor ranged from 13.7 to 217. The possible mechanisms of plasmon-resonant current enhancement are considered to be the effective photon absorption and photothermal effect.