Saw properties of Li2B4O7 crystals and their applications to acousto-optic waveguide modulators

Theoretical and experimental results have shown the potential usefulness of Li2B4O7 crystals for leaky SAW and acousto-optic applications. The shear leaky SAW has excited at (45 degrees, 90 degrees, 70 degrees), whose SAW properties are v(p) of 3680m/s, k(2) of 2.3% and TCD of 0. Further, k(2) of the Rayleigh SAW was zero at this cut substrate, which gives no spurious response for the temperature compensated shear leaky SAW. The longitudinal leaky SAW with the fast v(p) of 6825m/s has been also observed at the (0 degrees, 45 degrees, 90 degrees). Several amorphous thin films were successfully fabricated on the (110) LBO substrates by sputtering. Among them, the berate glass film has been a suitable material for acousto-optic applications because it has lower velocity and relatively larger index than those of LBO substrates.