ELECTROOPTIC TUNING AND SIDELOBE CONTROL IN ACOUSTOOPTIC TUNABLE FILTERS

Both the center wavelength and the sidelobe structure of an integrated acousto-optic tunable filter (AOTF) are determined by the effective waveguide birefringence along the length of the device. By altering the birefringence by means of the electro-optic effect, one can control these device characteristics in potentially useful ways. Electro-optic tuning of the center frequency of an AOTF is demonstrated, and it is shown that this tuning mode, while limited to smaller ranges than acoustic frequency tuning, is many orders of magnitude faster. By use of multisection electrodes, dynamic control over the shape of the filter function is demonstrated. Finally, a number of practical uses of this technique are discussed.