Digital Logic and Reconfigurable Interconnects Using Aluminum Gallium Arsenide Electro-Optic Fredkin Gates

This report describes digital logic operations and reconfigurable optical interconnects realized from aluminum gallium arsenide AlGaAs electro- optic Fredkin gates. The Fredkin gates fabricated for this effort were channel waveguide type passive and active AlGaAs zero-gap directional couplers ZGDCs. The first and logic gate reported in the open literature using AlGaAs ZGDCs is demonstrated along with a reconfigurable optical interconnect. Models predicting the refractive index of AlGaAs versus Al concentration and wavelength are treated. A model for predicting the electro-optic coefficient of AlGaAs versus Al concentration and wavelength is developed. Models for predicting the interaction length and switching voltage are optimized for AlGaAs. Fabrication techniques for AlGaAs ZGDCs are formulated. The performance of the actual AlGaAs ZGDCs fabricated for this effort fit the models exceptionally well. Correlation of experimental and theoretical results yielded a mole fraction of Al of 30 for the core and 35 for the cladding. A refractive index of 3.420 for 30 Al and 3.388 for 35 Al at lambda 827 nm were determined. A linear EO coefficient of r sub 41, -1.49 pmV at lambda 827 nm was inferred for the core layer. A switching voltage of 7.6 VDC was achieved for an AlGaAs ZGDC with a 5000 micrometers interaction channel length. Integrated optics, Fredkin gates, Zero-gap directional couplers, AlGaAs waveguides