BASEBAND INTEGRATED ACOUSTOOPTIC FREQUENCY SHIFTER MODULATOR MODULE FOR FIBER OPTIC AT 1.3 MU-M

A baseband integrated acousto-optic (AO) frequency shifter/modulator m odule that consists of a pair of titanium-indiffused proton-exchanged (TIPE) waveguide lenses and a pair of cascaded guided-wave AO Bragg ce lls has been realized in a Y-cut LiNbO3 waveguide substrate 0.1 cm by 1.0 cm by 2.0 cm in size. The device module operating at the optical w avelength of 1.3 mum has provided a -3-dB tunable bandwidth of 120 MHz at baseband. The frequency-shifted or -modulated light propagates in a fixed direction, irrespective of the magnitude of frequency shift or modulation, and is focused into a spot size (FWHM) of 6.2 mum upon th e output edge of the waveguide. Accordingly, this optical frequency sh ifter/modulator module can be directly interfaced with single-mode opt ical fibers to facilitate applications in fiber optic systems.