Fiber-optic polarization and phase modulator utilizing transparent piezofilm with indium tin oxide electrodes

Abstract

A highly efficient optical polarization and phase modulator formed by the placement of a thin transparent piezofilm with indium tin oxide electrodes directly in the path of the output from an optical fiber is presented. Various configurations that differ in the clamping conditions, utilization of epoxy, and optical arrangement are presented. For a film thickness of 63.9 µm, a linear phase-shifting coefficient of 0.131 rad@voltage peak 1Vp2 at 2 kHz and of 0.508 rad@Vp at 7.4 kHz is demonstrated. An intrinsic birefringence of 0.0328 between the directions along the stretch and its perpendicular in the plane of the film has been measured. The polarization modulation coefficient was determined to be 0.323 rad@Vp at 8.423 kHz, corresponding to a half-wave voltage of 8.353 Vp. Applications of the device involving concurrent spatiotemporal polarization and phase modulation are indicated.

Three-dimensional phase imaging with a scanning optical-fiber interferometer

“…The modulation of the phase difference between the two arms allows the separation of intensity and phase as described above. Several techniques can be used to produce a phase modulation in an optical fiber, including the wrapping of an optical fiber around a piezoceramic tube that expands radially, 20 the attachment of the fiber to a piezofilm to impart a longitudinal strain, 21 and the application of a piezoceramic coating to a fiber to stimulate radial acoustic modes. 22 We found that the first method introduces bending strains that increase coupling between core and cladding modes and hence coupling of the propagating mode to the external environment, leading to large signal instabilities.…”