High-speed PLZT optical switches for burst and packet switching

(Pb,La)(Zr,To)O₃ (PLZT) is one of the best candidates in terms of high-speed, low-voltage, and low-power consumption optical switching due to its efficient voltage-induced index change. We have established a solid-phase epitaxy to grow low-loss PLZT thin film waveguides. PLZT waveguides with PLZT buffer layers are grown on Nb-doped semiconductive SrTiO₃ substrates for the effective overlap integral of the optical field and the electric field. Efficient switching of light coupled in the waveguides is achieved by applying voltage between the top electrodes and the substrates to induce the excellent electro-optic properties of PLZT waveguides including low-voltage and polarization independent index change. 1timesN optical switching devices and subsystems are demonstrated using the PLZT waveguide switch elements showing low-voltage drive and less than 10 ns response characteristics