Abstract: Methods, circuits, and techniques for reflection cancellation. Laser output is tapped. A tapped portion of the laser output is phase shifted to generate a feedback signal, with the feedback signal being out-of-phase with a parasitic reflection of the laser output. The feedback signal is directed towards the laser such that the parasitic reflection and feedback signal are superpositioned before entering the laser. A magnitude and a phase of the feedback signal are such that superposition of the feedback signal and the parasitic reflection results in a resulting signal of lower magnitude than the parasitic reflection alone. During laser operation, a magnitude of the resulting signal is monitored and, as the parasitic reflection varies, the magnitude of the resulting signal is adjusted by adjusting at least one of the magnitude and the phase of the feedback signal in response to the monitoring of the resulting signal.

Abstract: An electric field sensing system is characterized so that a signal processor may derive an output representative of an electric field intended to be measured, particularly established by high voltage on a power line, with enhanced accuracy. Characterizing parameters may be derived from signals representative of a pair of light waves derived from a light wave exiting an optical electric field sensing element in a electric field sensing head spatially positioned in the high voltage environment.

Abstract: An electric field sensing system is characterized so that a signal processor may derive an output representative of an electric field intended to be measured, particularly established by high voltage on a power line, with enhanced accuracy. Characterizing parameters may be derived from signals representative of a pair of light waves derived from a light wave exiting an optical electric field sensing element in a electric field sensing head spatially positioned in the high voltage environment.

Abstract: An electro-optic modulator/mode-converter with slow wave electrode is formed on a semiconductor substrate incorporating a waveguide interposed between a pair of spaced parallel conductor strips each provided with fins projected toward the other electrode and in position relative to the waveguide to electro-optically affect the waveguide when voltage is applied to the conductor strips. The modulator requires significantly less power and operates at higher frequency than Mach-Zehnder type slow wave modulators.

Abstract: An optical switch biasing flow of light between a main optical waveguide and one or the other of a pair of secondary waveguides extending from one axial end of the main waveguide to define a Y structure with the secondary waveguides symmetrically positioned with respect to the longitudinal axis of the main waveguide is provided. A resonant conductor having a pair of legs each of which is operatively associated with the main waveguide and its respective adjacent one of the secondary waveguides generates a resonant voltage that directs the flow of light between the main waveguide and the secondary waveguide associated with the leg having an appropriate voltage.

Abstract: A slow-wave electrode structure suitable for use in integrated optical modulators having a pair of spaced substantially parallel integrated optical waveguides in a compound semi-conductor substrate (such as gallium arsenide (GaAs) or indium phosphide (InP)) is formed by a pair of substantially parallel conductor strips on the surface of the substrate each in a position for interaction with its respective adjacent of said waveguides. The conductor strips are capacitively interconnected by narrow fins each integral with one of the strips and extending between the strips whereby the conducting strips and fins may be applied as a single layer to the substrate. The narrow fins significantly increase the capacitance per unit length between the strips without an equivalent decrease in inductance per unit length along the strips such that the phase velocity of the microwave signals is reduced.

Abstract: An integrated optics Pockels cell for use in a voltage sensor includes a crystal exhibiting the electro-optic effect in which an integratd straight line wave guide substantially aligned with a z axis of the crystal is incorporated. The wave guide has two substantially orthogonal polarization axes substantially aligned with an x and y axis of the crystal respectively. In operation light polarized at a selected angle of orientation to the x and y axes of the crystal is applied to one end of the wave guide and polarized light leaving the wave guide and polarized along two substantially orthogonal axes one of which is at about the same orientation to the x and y axes as the polarized light entering the wave guide is detected to determine the electric field to which the sensor has been subjected. Preferably the sensor will include polarization maintaining optical fibers appropriately oriented to the wave guide for delivering and receiving polarized light to and from the wave guide.

Abstract: A voltage-induced optical waveguide modulator is disclosed in which the inter-electrode gap is significantly reduced to a width on the order of 4 microns. The use of a dielectric layer between the electrodes and the electro-optic substrate is disclosed. A ridge of the electro-optic substrate between the electrodes is also disclosed. The dimensions of the device and operating voltage may consequently be signficantly reduced.

Abstract: A high voltage sensor using an integrated optical Mach-Zehnder device is disclosed. A capacitive divider for sensing the electric field is connected to an electrode adjacent one of the parallel waveguide sections, while a second electrode adjacent the other section is grounded. The capacitive divider may be fabricated on the same substrate as the Mach-Zehnder device. Two similar devices which can be immersed in the electric field are also disclosed. In one case the device uses a Mach-Zehnder device having waveguides of the slab type. In this variation materials having two different refractive indices, both of which are low relative to the high index slab form the superstrates of the parallel waveguide sections. In the second variation, a Mach-Zehnder device having waveguides of the diffusion type is used. Thin films of high refractive index material are deposited over the two parallel waveguide sections, with the thickness and/or refractive index of the two film sections being different.