Abstract

The acousto-optic programmable dispersive filter (AOPDF) recently proposed [1] creates an optical output E_out(t) that is the convolution between an optical input E_in(t) and a time scaled electrical signal S (αt): The scaling factor α = Δn v/c is the ratio of the speed of sound to the speed of light times the index difference between the ordinary and extraordinary wave in the birefringent crystal used. We thus synthesise a filter of impulse response S(αt) (see figure), and because a is of order 10^-7 we can manipulate an optical signal in the hundred-THz range with an electrical signal in the ten-MHz range In our set-up [2], the S(t) signal is applied to a piezoelectric transducer to generate an acoustic wave in a 2.5 cm long TeO₂ crystal The centre frequency of S(t) is 50 MHz.

© 2000 IEEE