Experimental investigation on the use of photostrictive optical actuator for mems devices and verification with the FEA modeling results

Photostrictive materials are lanthanum-modified lead zirconate titanate (Pb, La)(Zr, Ti) O₃ ceramics doped with WO₃, called PLZT, exhibit large photostriction under uniform illumination of high-energy light. Photostrictive materials are ferrodielectric ceramics that have a photostrictive effect. Photostriction arises from a superposition of the photovoltaic effect, i.e. the generation of large voltage from the irradiation of light, and the converse-piezoelectric effect, i.e. expansion or contraction under the voltage applied. When noncentrosymmetric materials, such as ferroelectric single crystals or polarized ferroelectric ceramics, are uniformly illuminated, a high voltage, considerably exceeding the band gap energy, is generated. Along with this photovoltage, mechanical strain is also induced due to the converse piezoelectric effect. Photostrictive materials offer the potential for actuators with many advantages over traditional transducing electromechanical actuators made of shape memory alloys and electroceramics (piezoelectric and electrostrictive). Drawback of traditional actuators is that they require hard-wired connections to transmit the control signals which introduce electrical noise into the control signals; on the other hand PLZT actuators offer non-contact actuation, remote control, and immune from electric/magnetic disturbances.