Abstract: A travelling-wave Mach-Zehnder electro-optic modulator (10) for operation at microwave electrical input signal frequencies has an electrical modulation electrode structure (26,34) which constitutes a coplanar waveguide (24). An electrical input signal connector (80) is coupled to a microstrip line (38) having an output impedance which is significantly different from the input impedance of the waveguide (24). A Chebyshev impedance matching transformer (50) couples the input signal from the input connector (80) to the modulation electrode structure (26,34), while matching the output impedance of the microstrip line (38) to the input impedance of the waveguide (24) to maximize the coupling efficiency and minimize return loss. The modulatoGOVERNMENT RIGHTSThis invention was made with Government support under Contract No. N66604-87-C-1126 awarded by the Department of the Navy. The Government has certain rights in this invention.

Abstract: The present invention provides a method of preparing the surface of a lithium niobate substrate (10) having titanium optical waveguides (12) for a subsequent deposition of a coating material such as electrodes. This cleaning or etching step prior to the deposit of desired coating materials is accomplished without deterioration of the transmission capacities of the optical waveguides (12). The substrate cleaning step of the present invention comprises the introduction of a predetermined amount of oxygen (16) at a controlled rate to provide a predetermined atmospheric environment surrounding the lithium niobate substrate (10). The subsequent etching of the substrate surface to a predetermined depth, for example, by argon ion bombardment, provides minimal damage to the optical waveguides while still producing an excellently cleaned surface preparatory for receiving subsequent layer depositions such as the electrodes.

Abstract: The present invention is directed to a process and product of a process in the field of optical directional coupler switches. The application of laser light to the input ports of a coupler switch at a power level approximately twice or greater the operational power level that has been discovered to cause optical damage produces a remedial effect of stabilizing the switching characteristics of the optical coupler switch. The resulting optical coupler switch has improved transmission characteristics when measured by a transfer function over that of an untreated coupler switch.