Patent ID: 8582931

Claim:
A photonic integrated circuit (PIC) which generates an XOR function digital optical output from a pair of digital optical inputs, comprising: a substrate; a first set of optical waveguide devices on the substrate, with the first set of optical waveguide devices comprising a first electroabsorption modulator and a first photodetector which are electrically connected in series, with the first electroabsorption modulator receiving a first light portion split out from a first digital optical input of the pair of digital optical inputs by a first optical waveguide splitter on the substrate, and with the first photodetector receiving a second light portion split out from a second digital optical input of the pair of digital optical inputs by a second optical waveguide splitter on the substrate, and with the first photodetector generating from the second light portion a photocurrent signal which changes a reverse-bias voltage on the first electroabsorption modulator to generate a first inverted AND function output from the first light portion; a second set of optical waveguide devices on the substrate, with the second set of optical waveguide devices comprising a second electroabsorption modulator and a second photodetector which are electrically connected in series, with the second electroabsorption modulator receiving a third light portion split out from the second digital optical input by the second optical waveguide splitter, and with the second photodetector receiving a fourth light portion split out from the first digital optical input by the first optical waveguide splitter, and with the second photodetector generating from the fourth light portion another photodetector signal which changes the reverse-bias voltage on the second electroabsorption modulator to generate a second inverted AND function output from the third light portion; and an optical combiner to combine the first and second inverted AND function outputs to form the XOR function digital optical output.