Abstract: An optical connector comprises two optical connector bodies, each carrying an optical element such as an optical fiber, a lens, an optical source or an optical detector. Each optical connector body has a guide formation extending in a direction transverse to the optical axis of its respective optical element and a stop means extending in a direction transverse to its respective guide formation. Sliding engagement of the guide formations guides relative movement of the connector bodies in a direction transverse to the optical axes to bring the stop means into engagement and the optical axes into alignment. The optical connector is particularly suited to optical interconnection of circuit boards slidably mounted in card guides.

Abstract: An integrated circuit has integrated circuit cells drawn from a library. The cells are rectangular with input lines extending from both sides of the cell to a logic element on the cell and outputs taken from the logic element to both sides of the cell. Input and output lines terminate at connection points. Short linear lengths of conductors selectively interconnect the connection points across the boundary between adjacent cells. The arrangement permits on-cell series and parallel connection of cells.

Abstract: An optical fiber connector element comprises: a connector body having a passage extending therethrough, the passage having a forward portion for receiving an optical fiber and a rearward portion which is wider than the forward portion for receiving an optical fiber and surrounding protective material; and an optical fiber stub secured within the forward portion of the passage, the optical fiber stub having a forward end surface which has an optical finish. The connector element is used to terminate an optical fiber cable by: cutting the cable to a desired length; stripping back an end portion of protective material surrounding an optical fiber of the cable to expose an end portion of the optical fiber; and securing the exposed fiber end portion and an end portion of the protective material remaining on the fiber in the connector body passage with the fiber end portion in abutment and axial alignment with the fiber stub.

Abstract: In a method and apparatus for stabilizing the emission spectrum of a semiconductor laser diode, an external optical cavity is coupled to the laser diode to couple light from an active region of the laser diode to the external cavity and from the external cavity to the active region of the laser diode. The phase of light coupled from the external cavity to the active region of the laser diode is dithered about a phase operating point at a dither frequency. A component of the forward voltage across the laser at the dither frequency is sensed and a feedback signal indicative of the amplitude of said component of the forward voltage and the phase of said component of the forward voltage relative to the phase of the dither is generated. The phase operating point is changed in response to the feedback signal to minimize the amplitude of said component of the forward voltage. The method and apparatus are useful for stabilization of laser diodes used in high performance optical communications systems.

Abstract: An optical connector comprises two optical connector bodies, each carrying an optical element such as an optical fiber, a lens, an optical source or an optical detector. Each optical connector body has a guide formation extending in a direction transverse to the optical axis of its respective optical element and a stop means extending in a direction transverse to its respective guide formation. Sliding engagement of the guide formations guides relative movement of the connector bodies in a direction transverse to the optical axes to bring the stop means into engagement and the optical axes into alignment. The optical connector is particularly suited to optical interconnection of circuit boards slidably mounted in card guides.

Abstract: In a method and apparatus for plasma stripping a polymer photoresist coating from a semiconductor substrate, positively charged species are removed from an activated gas flow before the gas flow is brought into contact with the coating to strip the coating from the substrate. The positively charged species may be removed by bringing the activated gas into contact with a grounded conducting surface to discharge the positively charged species, or by passing the activated gas through a negatively charged electrostatic filter to filter out positively charged species. The removal of positively charged species from the gas flow reduces or eliminates build up of positive charge on an outer surface of the photoresist coating so as to avoid driving mobile positively charged ions from the photoresist into the substrate, thereby avoiding contamination of the substrate.

Abstract: In a method for Liquid Phase Epitaxy (LPE) of semi-insulating InP, a solution of P, Ti and a p-type dopant in molten In is cooled in a non-oxidizing ambient at a surface of a substrate to grow an epitaxial layer of doped InP on the surface. The concentration of p-type dopant in the solution is such as to provide a concentration of p-type dopant in the grown epitaxial layer greater than the aggregate concentration of any residual contaminants in the grown epitaxial layer, and the concentration of Ti in the solution is such as to provide a concentration of Ti in the grown epitaxial layer greater than the concentration of p-type dopant in the grown epitaxial layer. The required melt concentrations are determined empirically. The method can be performed at temperature below 650 degrees Celsius and is particularly suited to the LPE growth of semi-insulating InP to isolate InP-InGaAsP buried heterostructure lasers.

Abstract: In the monolithic integration of HFET and DOES devices, a wide band gap carrier confining semiconductor layer is provided only at predetermined locations where DOES devices are desired. This layer is not provided at other predetermined locations where HFET devices are desired as it would constitute a shunt path which would degrade the high frequency operation of the HFET devices. The invention is particularly useful where monolithic integration of optical sources, optical detectors, and electronic amplifying or switching elements is desired.

Abstract: In a method and apparatus for plasma stripping a polymer photoresist coating from a semiconductor substrate, ultraviolet radiation generated as a byproduct of plasma generation is absorbed by a baffle placed between a plasma source and the substrate. The baffle inhibits incidence of ultraviolet light on the substrate while permitting flow of activated gas onto the substrate to chemically strip the photoresist from the substrate. Use of the baffle reduces microscopic damage to the substrate.

Abstract: In a method and apparatus for discriminating between a broadband unipolar signal having a component within one or more of three predetermined frequency bands and a narrowband signal within one of the frequency bands, a signal under test is amplified by a gain which is inversely proportional to the DC content of the signal under test to normalize the signal under test. The normalized signal is bandpass filtered to attenuate components outside of the predetermined frequency bands and the filtered signal is compared to a reference signal. The signal under test is deemed to be a narrowband signal within one of the predetermined frequency bands if the filtered signal exceeds the reference signal. The method and apparatus are particularly useful for detecting test tones on optical fibers.

Abstract: In an optical fiber connector having a snap lock latching arrangement, internal springs act between housings and fiber holding inserts to bias the fiber holding inserts axially together into an alignment sleeve and to bias the housings axially apart to a stop position at which latching formations on the housings abut axially together. The biasing arrangement inhibits relative axial movement of the inserts and housings which would result in variable insertion loss at the connection. Stop formations provided on one of the housings center the housings with respect to one another to facilitate disengagement of the snap lock engagement.

Abstract: A silicon-on-insulator substrate having a very low threading dislocation density is made by implanting oxygen ions into a silicon substrate while heating the substrate to form a layer of silicon dioxide buried in the silicon substrate and annealing the implanted substrate at high temperature in a novel furnace incorporating a polysilicon tube to constrain the annealing temperature to be uniform over the entire substrate. The silicon-on-insulator substrate is particularly useful for the manufacture of semiconductor devices formed in thin silicon films.

Abstract: An optical switch has a reciprocating prism. In one position of the prism, light passes from an input fiber, through a collimating lens, directly to a focussing lens and then into an output fiber. In another prism position, the collimated light is incident on the prism, is deflected by the prism and enters a different focussing lens and output fiber. Coaxially aligned with the lenses are respective precision molded conical recesses which flare outwardly to receive the precision ground conical ends of fiber terminations.

Abstract: In the making of an electrical cable, a metal shield is formed by wrapping metal strip around a cable core with longitudinal edges of the strip overlapping. The strip is corrugated with the corrugations nesting in the overlapped regions. A shield gap filler is provided by extruding a heated molten plastics material and directing it between the overlapped regions. Upon cooling, the filler hardens and bonds the edges together. A cable jacket is extruded around the shield.

Abstract: In a method for splicing filaments, respective end portions of two filaments are held in overlapping condition in a holding device comprising two axially spaced rubber holders, each holder having a radial slot for receiving and retaining the overlapped end portions. One of the holders is rotated relative to the other to twist together the overlapping end portions. The holders are then fixed against relative rotation, and the twisted together end portions are fused together to form a splice of substantially circular cross-section. The method and device are useful for splicing plastic coated glass yarn used to reinforce telecommunications cables.

Abstract: In a method and apparatus for making a cable core, cable core units are stranded together while drawing the cable core units along a passline through a closing die and while vibrating the closing die. Vibration of the closing die facilitates movement of insulated conductors of the cable core units over one another to provide a greater and more uniform packing density of conductors in the resulting cable core.