Abstract: A pulse decoder for decoding digitally coded data, each data bit being represented by a coding scheme consisting of a combination of short and long duration pulses having a predetermined interrelationship. The decoder has an input for receiving an input signal defining respective long and short time periods derived from the digitally coded data. An analog signal processing element generates output pulses from the input signal. The output pulses have a variable duty cycle dependent on the input signal and a control parameter. A feedback loop generates a control signal for adjusting the control parameter so that the duty cycle of the output signal matches the predetermined relationship.

Abstract: An SRAM has a bit cell for storing a data bit in voltage mode at a data node, and a single bit line for respectively writing to and reading from said data node a data bit in reference current controlled mode. The SRAM has ultra low power consumption and can be used in word based SRAMs.

Abstract: A method of carrying out the controlled oxidation of A material, such as Al(Ga)As is oxidized in a controlled manner placing it in a reactor, and causing a carrier gas containing an oxidizing vapour, such as water, at a controlled partial pressure to flow over the oxidizable Material. In this way, the reaction process can be made sensitive to only one variable.

Abstract: A vertical cavity surface emitting laser (VCSEL) having asymmetrical optical confinement is described. Polarization of VCSELs having symmetrical structures tend to be unpredictable and switchable. The VCSEL of the present invention has a dielectric stack on top of the emitting distributed Bragg mirror. The stack is made up of two or more layers of dielectric material with each alternate layer having one of two different refractive indexes. In a preferred embodiment an antireflective coating is between the top mirror and the dielectric layers. The stack is preferably smaller than the emitting aperture.

Abstract: A system and method for individually controlling channels of a multi-channel optical communications system are described. The optical communications system uses optical transmitters such as semi-conductor lasers for each channel. A drive circuit provides energizing energy to each laser in order to generate a modulated output. In the present invention a programmable memory such as an EPROM is used to individually control drive conditions for each laser in order to tailor the output.

Abstract: A vertical cavity surface emitting laser (VCSEL) having asymmetrical optical confinement is described. Polarization of VCSELs having symmetrical structures tend to be unpredictable and switchable. The VCSEL of the present invention has vertically etched apertures into the top bragg mirror in order to confine the optical path into an asymmetric structure. This has the effect of locking polarization into a fixed mode.

Abstract: A photodetector includes a detector responsive to incident light to generate an output signal and one or more band gap filters upstream of the broadband detector for absorbing incident photons of predetermined wavelength. The bandgap filters have a bandgap gradient across their width. The photodetector can act as a selective detector without the need for a separate optical filter.

Abstract: A method of making an optical device on a carrier plate involves defining on one side of the carrier plate electrical contacts and through-holes for guide pins by a photolithographic process. The components are then mounted on the contacts and the guide pins of are mounted through the through-holes, using the through-holes as guides.

Abstract: An optical connector includes a supporting block, a pair of guide pins protruding from the supporting block for mating with a connecting component, and an array of active optical components recessed into the supporting block so that a void is present between the active optical components and optic fibers carried by the connecting component. A transparent filler material the void and provides a light path between the active optical components and the optic fibers.

Abstract: A method is disclosed for making an active optical device for coupling to optical fibers. Arrays of contacts are formed on the rear face of a substrate, which is preferably transparent, at precisely defined locations. Components are then flip-cup bonded onto the substrate using a solder alignment technique to attach the components to said substrate in precisely predetermined locations determined by the arrays of contacts. At least one of the components is a light emitter or receiver so that it can be optically coupled through the transparent substrate to an external light guide on the front face of the substrate. Preferably, a guide frame for positioning guide pins is bonded to the substrate also using a solder alignment technique.

Abstract: A circuit for lowering the effective voltage drop of a semi-conductor diode. The circuit includes a first Metal Oxide Semi-conductor (MOS) device connected in parallel with the diode. A bias voltage which is close to but lower than the threshold voltage is applied to the MOS device. When a forward voltage is applied to the diode, this voltage is added to the source to drain voltage of the MOS device which turns it on. The MOS device then bypasses the diode to effectively overcome the inherent forward voltage drop of the diode. The circuit is advantageously applied to a rectifier circuit to reduce input voltage requirements and improve the efficiency of the rectifier.

Abstract: An optical taper is used to couple an optical fiber to the active area of an optical receiver,. The optical taper funnels light from the optical fiber through optical taper to the optical receiver and in this way facilitates alignment of the optical fiber.

Abstract: A method and system for use in accurately aligning components in a multi element electro-optic assembly. One or more guiding pins are provided in association with one layer of the assembly. Each remaining layer is provided with cooperating guiding means which mate with the guide pins in a manner whereby the various optical components are accurately aligned upon completion of the fabrication process. The system and method reduces the assembly time required by the typical time consuming active alignment technique.

Abstract: A method and system for measuring performance characteristics such as bit error rate (BER) in a multiple parallel-channel digital communications system. A transmitter such as a VCSEL array outputs multiple, high data rate, digital signals onto an appropriate media for reception at a receiving end. The test architecture uses a test pattern generator at the transmitter end and a data re-shaper connected to a receiver in each channel. The output of each re-shaper is serially connected back into the next channel transmitter until each channel has been tested. An error detector connected serially to the last receiver provides an evaluation of the characteristics of the multiple channels.