LOW-SIDELOBE WEIGHTED-COUPLED INTEGRATED ACOUSTOOPTIC TUNABLE FILTER USING FOCUSED SURFACE ACOUSTIC-WAVES

A single-stage low-sidelobe weighted-coupled integrated acoustooptic tunable filter (IAOTF) operating at the optical wavelength of 1.31 mum has been realized on a Y-cut X-propagating LiNbO3 substrate for the first time. The weighted-coupling, which enabled the achievement of low-sidelobe levels, was facilitated by focused surface acoustic waves generated by a curved interdigital transducer. First sidelobe levels as low as -17.6 dB have been obtained. Optical bandwidth of 4 nm and tuning range of 170 nm for an interaction length of 6 mm were also accomplished.