Abstract: A seed light source for use in Wavelength Division Multiplexed Passive Optical Network (WDM-PON) includes a multi-channel quantum dot laser for generating a multi-channel seed light comprising a plurality of respective channel seed lights. Each channel seed light corresponds to a respective channel of the WDM-PON.

Abstract: A control system is designed to control an optical cross-connect having a switch core defined by first and second independently movable beam deflectors capable of selectively defining an optical path between a pair of ports of the optical cross-connect. An optical element having optical power is arranged in a propagation path of light beams between the first and second beam deflectors. The control system includes a pilot light source, an optical sensor associated with each beam deflector, and a feedback path. The a pilot light source inserts a pilot light into the switch core colinearly with live traffic. The optical sensor detects a predetermined geometric property of the pilot light emerging from the switch core. This predetermined geometric property is unambiguously associated with an angular position of the associated beam deflector. The feedback path actively controls a position of the associated beam deflector based on the detected geometric property.

Abstract: A control system is designed to control an optical cross-connect having a switch core defined by first and second independently movable beam deflectors capable of selectively defining an optical path between a pair of ports of the optical cross-connect. An optical element having optical power is arranged in a propagation path of light beams between the first and second beam deflectors. The control system includes a pilot light source, an optical sensor associated with each beam deflector, and a feedback path. The a pilot light source inserts a pilot light into the switch core colinearly with live traffic. The optical sensor detects a predetermined geometric property of the pilot light emerging from the switch core. This predetermined geometric property is unambiguously associated with an angular position of the associated beam deflector. The feedback path actively controls a position of the associated beam deflector based on the detected geometric property.

Abstract: A Mach Zehnder (MZ) modulator with improved coupling of input and output fibers is provided. The MZ modulator combines the advantages of weakly guided input sections with strongly guided sections to optimize the coupling efficiency and selectivity of the device. Improved coupling between weakly and strongly guided sections of waveguide is provided by an intermediate tapered waveguide section which provides gradually changing mode confinement, which reduces the mode mismatch loss and therefore suppresses the reflection at the junction between the weakly and strongly guided sections of the waveguide.

Abstract: A MQW semiconductor Mach Zehnder phase modulator is formed by two Y-junctions (12, 32), each having a single waveguide (14) optically coupled with two branch waveguides (18, 20). The branch waveguides of the two Y-juntions are optically coupled in Mach-Zehnder configuration that, under zero bias conditions, has one interferometric arm longer than the other to provide a .pi. phase shift. The additional length is preferably accommodated in the branches of the Y-junctions. The phase shift, in combination with voltage dependent absorption properties and non-linear phase variations of the MQW guided regions in the Mach-Zehnder modulator results in a negative chirp and high extinction ratio for an equal, push-pull device configuration.

Abstract: A Mach-Zehnder optical modulator in which the chirp parameter can be varied by adjusting the optical power splitting ratio between the two arms of the interferometer. The modulating voltage is supplied to a single arm or alternatively to both arms in a push-pull configuration. For an appropriate power splitting ratio negative chirp is achieved with approximately equal push-pull modulating drive voltage. This results in optimum distance and bit rate characteristics with low drive power.

Abstract: A semiconductor-based optical phase-modulating device has first and second pairs of phase-fixing electrodes bracketing a pair of phase-modulating electrodes. The phase-fixing electrodes fix electric fields across end regions of the phase-modulating device to reduce distributed resistance and capacitance of the phase-modulating device, thereby improving the frequency response of the phase-modulating device. The optical phase-modulating device is particularly applicable to use in integrated optic Mach-Zehnder interferometers used for optical signal modulation.

Abstract: A heat-recoverable article comprises a heat-shrinkable sleeve having an elongate electrical conductor retained therein. The conductor projects from at least one end of the sleeve and at least a portion of the length of the conductor within the sleeve is uninsulated, there being a quantity of solder, which is positioned eccentrically in the sleeve, on at least part of the said uninsulated portion. Articles wherein the conductor is an earth conductor may be used to connect the earth conductor to a substrate, for example the outer conductor of a coaxial cable, inserted into the sleeve.

Abstract: Wire insertion and trimming apparatus comprising two wire locating combs opposed on opposite sides of a connector-supporting bed, a wire insertion and trimming ram reciprocable relative to the bed, and a third comb movable from a position remote from the bed to a position adjacent the bed to permit loading the connector onto the bed and wire insertion. Preferably, means are provided to latch the third comb remote from the bed which means are releasable by loading a connector and the two combs are movable after wire insertion in cooperation with the latching means to eject the connector.