LIGHT SWITCHING IN A GLASS-AG-POLYMER STRUCTURE USING ATTENUATED TOTAL-REFLECTION (ATR)

Surface plasmon resonance (SPR) and a photon-tunneling modes were observed in the visible spectrum using a glass-silver-PVC-Mylar structure. This structure was used as an electro-optic device to modulate the reflected intensity of a He-Ne (632.8 nm) beam by more than a factor of 2. Low-frequency switching was achieved in the 0-40 Hz range with a driving amplitude in excess of 50 V. Results suggest the low-frequency response is governed mostly by ionic migration within the polymer and the perturbation of the evanescent field matching condition at the silver-PVC interface results in the modulation. As light-switching time is related to species mobility, the technique should be a good probe for studying ionic migration in polymers or biological membranes.