Abstract

Two evanescent waves are generated by division of a laser beam by total internal reflection. Two separated rectangular prisms are used to form a narrow gap of the order of 1 wavelength. The gap width is modulated by two plate piezoelectric transducers with a resonance frequency of ~10 MHz. A third prism is used to change the direction of one beam, and as a result the two beams reaching the separated surfaces from opposite sides form two evanescent waves that propagate in parallel but opposite directions. At first one of the beams is turned off, and we measure the tunneling intensity of the other one. Matched evanescent waves interact with each other to form a propagating wave, so that as the previously extinguished beam is turned on, there is an interaction between the two evanescent waves that may change the tunneling intensities of both beams, which are also modulated by transducers. A plate with varying thickness is inserted into one beam to adjust the relative phase between the two waves.

© 1987 Optical Society of America