Piezoelectric thin-film unimorph actuator for optical fibre alignment applications

Feasibility of a piezoelectric unimorph thin-film actuator for optical fibre alignment was investigated. The main interest was focused on the fabrication, and electrical and mechanical characterization of a low-voltage driven component which was small-sized, efficient and suitable for integration into the low-temperature co-fired ceramic (LTCC) environment. Lead zirconate titanate (PZT) was chosen as ferroelectric thin-film material due to its excellent piezoelectric properties. A specific thin-film actuator structure was designed, modelled, and fabricated on silicon substrates. The structural, electrical and mechanical properties of the actuator structures were characterized, and the actuator structures were hybrid-integrated on LTCC substrates together with optical fibres to form a cantilever-type high-precision alignment device. Using a semiconductor laser diode as a light source, the alignment of an optical fibre was tested. Cantilever displacements up to 57 µm were achieved enabling adjustability of optical power coupling.