Abstract: An optical transducer (10) having a plurality of concentric cores (15,17). An intermediate cladding (16) is disposed between the inner and outer cores and an outer cladding (18) surrounds the outer core to define a symmetrical cylindrical transducer structure. Light propagated through the inner core (15) from a source (19) is coupled into the outer core (17) as a result of penetration of the evanescent electric field from the light in the inner core through the inner cladding (16) to the outer core. Control of the coupling length may be effected by suitable selection of the transducer structure parameters. At least one of the portions of the transducer is formed of an acousto-optically variable material whereby an acoustic field acting on the transducer causes a modulation of the coupled light so as to provide in the outer core (17) a modulated light signal suitable for detection by a receiver (21). Localized control of the parameters of the transducer may be effected to provide focusing of the coupled light.

Abstract: A transducer (14) including an optical fiber core (15) having a first refractive index profile, and an optical cladding (16) encircling the core and having a second refractive index profile different from that of the profile of the optical core. At least one of the core and cladding is formed of a photoresponsive material providing a variable difference between the refractive indices of the core and cladding as a function of a physical effect applied to the transducer. Light may be propagated through the core from a suitable light source (18) and the light which is lost from the core to the cladding may be detected by a suitable detector (22,23) providing an output signal corresponding to the force applied to the transducer. In one form, the detector receives light from the end (21) of the transducer, and in another form, the detector (23) receives light through the outer surface (24) of the transducer.