Abstract: Surface plasmon resonance in small particles of metal is employed to polarize light propagating in a waveguide. An ion-exchanged glass waveguide is provided with a 50 Angstrom (5 nm) mass thick layer of silver which is deposited on the waveguide. The ion-exchanged glass waveguide having the specified layer of silver is annealed at 200.degree. C. for 1 minute causing the silver film to bead, much like water droplets on a waxed car. The silver microparticles have a nonspherical shape with their major axes parallel to the surface of the waveguide and their minor axis perpendicular to the surface of the waveguide as illustrated in the Figures of the Drawing. When light from a HeNe laser at a wavelength of 633 nm is prism-coupled into the waveguide with the field of laser beam parallel to the major axes of the spheroids (TE polarization) the laser light is strongly absorbed and the TM light is passed.