Abstract: A linear optical broadband signal generator includes primary and secondary optical modulators whose outputs are combined so as to minimize intermodulation distortion of a modulated optical signal. A constant amplitude optical signal is split differentially so as to create primary and secondary power levels, the primary and secondary power levels being inputted into the primary and secondary modulators. An electrical input to one of the modulators is differentially attenuated so as to reduce third order modulation products when modulated outputs of the modulators are combined. In addition, the total modulated optical output power is maximized by adjustment to one of the outputs of one of the modulators so that its phase is more in line with a phase of the output of the other modulator so as to maximize first order products of the combined output.

Abstract: An optical fiber waveguide tap handling tray is provided for use with a cable containing a plurality of optical fiber waveguides which are separated from the cable and exposed in a section thereof. The tap handling tray comprises a frame, a clamp for clamping the cable to the frame adjacent the section thereof so that the exposed optical fiber waveguides are thereupon physically secured to and contained within the frame, at least one optical tap secured to the frame for engaging and bending at least one of the plurality of optical fiber waveguides against an optical coupling medium having an index of refraction selected to match the index of refraction of the optical fiber so that light energy may pass through a side of the optical fiber and through the optical coupling medium, and wherein the optical tap defines an obtuse guiding angle arranged to lie in a path with which the fiber may freely be aligned within the frame after the cable has been clamped thereto.

Abstract: An optical fiber enclosure for a pedestal environment includes a pedestal which slideably supports a closure within the pedestal along a vertical direction so that during freeze-thaw envionrmental conditions when the pedestal is raised and lowered by expanding and contracting earth the closure does not impose undue stress on optical fiber cables connected thereto. Another enclosure suitable for buried applications also includes means for slideably extending an inner closure therefrom along a vertical direction to aid a craftsperson in accessing and working on the inner closure, the buried enclosure including means for allowing one or more loops of telecommunications cable to be stored therewithin for allowing the inner closure to be removed a substantial distance therefrom.

Abstract: A coupler verification test circuit includes first and second circuits one of which is disposed at a head end of an optical fiber network and the other of which is disposed at a subscriber interface unit to be attached to the network when the head end is not operational. The subscriber interface circuit transmits instructions to a transceiver board in the subscriber interface unit for transmission to the network head end whereat the circuit thereat generates either no return signal, an acknowledgment return signal, or a default return signal. The test circuit at the subscriber interface unit then analyzes the return signal and visually indicates to a craftsman whether or not the transceiver board and other components of the SIU are operating correctly, e.g. whether or not the acknowledgement signal was returned and detected.

Abstract: A method and apparatus implementing the method are provided for controlling optical power output level of a laser diode modulated during a burst mode interval by digital data transitions within a shared logical bus optical communications network and over a predetermined thermal gradient. The method comprises the steps of: optically monitoring a component of the optical output power of the laser diode during each burst mode interval and converting the component into a control signal, establishing a reference signal and comparing the control signal with the established reference signal and for providing a logical condition from said comparison, generating a strobe signal from information related in time to the burst mode interval, storing the logical condition upon receipt of the strobe signal, integrating the stored logical condition over a time period to provide an integrated control signal, and regulating current flow through the laser diode in accordance with the integrated control signal.

Abstract: A method of providing optical signal transmission past an optical fiber section in need of repair includes withdrawing an optical signal from the fiber upstream of the section and injecting the signal into the fiber downstream of the section in a passive manner while the section is being repaired.

Abstract: An optical coupler for coupling light between an optical fiber core and an electrooptic transducer includes a pin and channel arrangement associated with a mechanism for opening and closing the coupler. At one position the pin engages an end of the channel whereat the coupler is open and safe insertion or removal of the fiber from the coupler is possible. At a second position, the pin engages another end of the channel and an optical fiber previously inserted into the coupler when in its open position is securely locked in the optical coupler.

Abstract: An optical fiber network includes a single mode silica core/cladding optical fiber having a cutoff wavelength in the range of about 1000-1200 nanometers, and a plurality of optical couplers serially disposed on the optical fiber so as to form a bus network, with each optical coupler injecting its own unique optical signal into the optical fiber so as to be multiplexed in time, each optical signal injected having a dominant light intensity wavelength below the cutoff wavelength of the optical fiber. Each injected signal propagates initially via a plurality of modes.

Abstract: An inrush current limiting circuit in accordance with the principles of the present invention limits initial current flow to a highly initially reactive power load. The current limiting circuit comprises a plug in connection to a power source and two conductor paths leading from the plug in connection. A power FET has a source element to drain element path in series with one of the conductor paths and has a gate connection. A bipolar transistor is connected to shunt the gate element of the power FET to the potential at its source element when the bipolar transistor is conducting, thereby to limit the current passing through the power FET. A sense resistor is in series with one of the conductor paths for controlling a base element of the bipolar transistor to cause it to conduct when current through the sense resistor exceeds a predetermined amount.

Abstract: A cable block for telecommunications cable includes first and second half shell members which together form a substantially cylindrical stepped longitudinal bore therethrough, portions of the bore being sealingly engaged against progressive stripped outer parts of a stripped part of the cable so as to sealingly engage against each intermediate layer thereof which could form a water channel between its adjacent cable layer. Metal pins are also provided which extend into the channel and electrically connect to a ground shield of the cable for dissipating electrical currents during current surges as can occur when lightening strikes. The cable block is useable for terminating an end of a cable of an intermediate section thereof at which access to the telecommunications conduction media is required without breaking the conduction media.

Abstract: A digital phase acquisition circuit includes circuits for detecting an edge of incoming data and a plurality of candidate clock phases, the circuitry further including logic for determining when the data undergoes a predetermined phase transition and at least one candidate phase which undergoes a digitally equivalent transition close in time to the data transition so as to enable the candidate phase to be used for choosing an appropriate clock phase for recovering information representative of the data. The circuit further includes logic for comparing a frequency of the chosen clock pulse and the data and adjusting at least one of these frequencies when a predetermined amount of drift therebetween is detected. The invention allows clock to be recovered within 1 bit time of a predetermined data transition occurring and allows an appropriate clock to be maintained through an entire packet regardless of packet length.

Abstract: A laser diode protection circuit includes an input connected to receive the RF amplitude modulating signal. A second RF amplifier is connected to amplify the received RF amplitude modulating signal and to put out an amplified signal. A sensing element such as differential amplifier or Schmitt trigger is connected to put out a control signal when the amplified signal exceeds in amplitude a reference level. A switching element preferably includes a series PIN diode network having a PIN diode connected in parallel in reverse conduction order across the laser diode. The switching arrangement is responsive to the control signal and effectively swamps or diverts the forward conduction current away from the laser diode thereby causing it to become reverse biased.

Abstract: Forming an optical fiber so as to have a relatively constant bend loss characteristic includes apparatus for continuously bending the optical fiber downstream from a preform from which it is drawn and continuously detecting light withdrawn from the fiber at the bend so created to determine the fiber bend loss characteristic, the fiber bend loss characteristic being maintained constant by using feedback control to vary a drawing speed of the fiber and hence a diameter of a core of the fiber.

Abstract: An optical fiber tap for connecting polymer optical fibers is achieved by heating an end section of the fibers to be connected and deforming the end sections into a non-circular cross-sectional shape so as to form a throughput cross-sectional area and a add/drop throughput area, the optical fiber ends being thereafter aligned so as to allow for efficient signal extraction and injection.

Abstract: A D-shaped fiber which has an evanescent-field which is easily tapable has a low attenuation since a buffer material disposed on a cladding planar side of the waveguide has an index of refraction lower than the cladding so as to effectively increase a radius of the cladding in the vicinity of its planar side so as to minimize signal loss into the fiber buffer.