Slow surface plasmons in amplifying media and ultrahigh-resolution nonlinear optical microscopy

The technique of ultrahigh-resolution nonlinear fluorescent microscopy based on standing surface plasmons is proposed. On the wavelength of a surface plasmon of 20 nm the expected lateral resolution should be 1–2 nm. Slow surface plasmons with the required mean free path of ～1 m are possible in the planar amplifying medium-metal-dielectric structures due to the compensation of loss in the metal by the amplification in the active medium. In the optical and near infrared range the undamped surface plasmons with the wavelength of 20–50 nm in thin silver films can be obtained at the material gain of active medium of (1–2) × 10⁴ cm ^?1. Possibilities of obtaining this gain in the plasmon structures remain to be seen.