Novel inter-core-cladding lithium niobate thin-film-coated fiber modulator/sensor

An fiber modulator/sensor has been fabricated by depositing a lithium niobate sol-gel thin film between the core and cladding of a fiber preform. The preform is then drawn into 125 um fiber. The proposed design of lithium niobate cylinder fibers can enhance the existing methdology for detecting sound waves under water utilizing the acoustooptic properties of lithium niobate. Upon application of a stress or strain, light propagating inside the core, acording to the principle of total internal reflection, escapes into the cladding because of the photoelastic boundary layer of lithium niobate. Test results of the lithium niobate fiber reveal a reduction in the 1550 nm, 4 mW source with applied tension. The source power from an ordinary quartz fiber under the same stress condition remained invariant to applied tension.