Deflection of electromagnetic beams from guides by acoustical surface waves

Claim 1

Apparatus for deflecting a beam of optical electromagnetic wave energy comprising a first optically transparent body forming a substrate for a second optically transparent body of higher refractive index than said first body, said second optically transparent body having two substantially parallel major surfaces separated by a distance of the order of the optical wavelength of the electromagnetic beam to be deflected, one of said surfaces forming an interface with said first body, means for launching said electromagnetic beam into said second body along an axis in a guided mode therein, means for launching an acoustical surface wave in said second body localized near the other of said surfaces thereof and propagating substantially aligned with the axis of said beam, said acoustical wave launching means including a source of an electrical driving signal of frequency variable through a selected range, said electromagnetic beam and said acoustical surface wave being propagated in modes in said second body having phase propagation constants related according to Beta s'' Beta o + OR - Beta a where Beta s'', Beta o, and Beta a are the phase propagation constants for the deflected electromagnetic beam, the guided electromagnetic beam and the acoustical surface wave, respectively, in said second body, and the phase propagation constant of said deflected electromagnetic beam Beta s'' in said second body being less than the phase propagation constant of said deflected beam in said first body, a portion of said beam being deflected from said guided mode in said second body into a single mode propagating out of said second body through said interface into said first body at an angle with respect to said interface substantially directly related to the frequency of said electrical driving signal.