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We designed, fabricated, and characterized varifocal microlenses, whose focal length varies along with the deformation of a transparent elastomer membrane under hydraulic pressure tailored by electroactive polymer actuators. The microfluidic channel of the microlens was designed to be embedded between silicon and glass so that transient fluctuation of the optical fluid and elastomer membrane is effectively suppressed, and thus the microlens is optically stabilized in a reduced time. Multilayered poly(vinylidene fluoride-trifluoroethylene-clorotrifluoroethylene) actuators were also developed and integrated onto the microfluidic chambers. We demonstrated that the developed microlenses are suitable for use in microimaging systems to make their foci tunable.

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Unidirectional characteristics of two-level split finger transducers are calculated as functions of the structure parameters, for several electrode materials (Al, Cu, Au etc.) on ST-X quartz, by using a method based on boundary integral equations for the grating structure. The calculation results show that the two-level structures have sufficiently large reflectivity by choosing the electrode materials and modifying the structure parameters. Moreover, 190 MHz range two-level structure filters are fabricated by using high accurate mask alignment techniques with a position error of 50nm. The experiments show a good agreement with the calculations. It is found that the two-level split finger transducers have a larger transduction coefficient and a high reflectivity, compared with other SPUDTs such as a distributed acoustic reflection transducer (DART) or an electrode width control (EWC) SPUDT. It is therefore possible to reduce an insertion loss of the SPUDT filters.