Wavelength selection with coupled surface plasmon waves

A process by which optical wavelengths can be selected by changing coupling distance of two surface plasmon waves is reported. When two surface plasmon waves are excited at metal/air/metal interfaces, coupling of the two surface plasmon waves will only allow a range of certain wavelengths to transmit. This wavelength selection depends on thickness of the air gap, and it does not have repeated passbands at harmonics. This phenomenon can be used to build broad-range tunable filters and spectrometers. Experiment showed the peak transmission wavelength could be continuously tuned from 400 to 900 nm with different voltages.