The Desirability of Electrooptic Ferroelectric Materials for Guided-Wave Optics

An illustrative, device-systems-level desirability optimization analysis has been performed for a number of important electrooptic materials that are candidate for use in high-speed guided-wave optical devices. Ferroel ect r ic materials with high and low transition temperatures, cubic crystals, organic crystals, and alloy semiconductors have been considered. The bulk guided-wave phase modulator has been taken as the initial screening device. Performance measures such as electrical power supply constraints and the device's maximum operating speed have been analyzed as a function of system variables that include material properties and electrode architectures. Desirability analysis has been presented as a composite mathematical function that describes two or more independent performance measures in terms of all relevant system variables. This function has been displayed graphically to identify those sets of system variables that jointly optimize the performance measures o f greatest interest. The initial screening analysis has ignored propagation loss and less-than-ideal overlap between electrical and optical fields. Potassium niobate, barium titanate, and lithium niobate have been found to be among the more desirable electrooptic materials. The use of dielectric buffer layers, several thousand Angstroms in thickness, has been found necessary to isolate the modulator el high dielectric constant, high strength materials such as potass Buffer layers, however, have been generally unnecessary when using permittivity and lower electroopt materials such as lithium niobate. ctrodes f rom electroopt ic um niobate. ound to be the lower c strength