ANALYSIS AND FABRICATION OF OVERLAPPING-ELECTRODE DESIGNS FOR POLING AND MODULATING CHANNELS IN POLYMER THIN-FILMS

A design for overlapping electrodes for use with thin-film nonlinear optical polymer waveguides is analyzed. The suggested electrode structure serves both to pole birefringent waveguides in a polymer thin film and to apply rf modulation to the waveguide thus defined. This structure is also designed to minimize capacitance, to maximize electro-optic overlap, and to not require a conducting substrate or surface coating of the substrate. A figure-of-merit is developed to optimize both the longitudinal and the transverse geometry of this electrode structure. A fabrication approach to this general design is presented. Optical characterization data are presented for prototype optical phase modulators fabricated by this design. Fiber coupling losses, propagation losses, and dependence of propagation losses upon cladding thicknesses, composition, and electrode composition are presented.