Abstract: A laser system is provided that includes a modulated laser, which is configured to generate an amplitude modulated laser signal, comprising a first amplitude modulation. The first amplitude modulation is based on a data signal. Moreover, the laser system includes an optical modulator, which is configured to receive the amplitude modulated laser signal as an input signal, and modulate the amplitude modulated laser signal with a second amplitude modulation, based on the data signal, resulting in an amplitude modulated output laser signal.

Abstract: The present invention relates to the introduction of an outstation into an optical network. The optical network has a central station, and a plurality of previously introduced outstations which are optically connected to the central station. The network is operable in: a normal operating state in which data traffic is received from previously introduced outstations at a normal data rate; and, a set-up state in which the transmission of data traffic from the previously introduced outstations is restricted relative to the normal state, the method including the step of: when the network is in the set-up state, performing a set-up operation for introducing the outstation into the optical network, the set-up operation involving the transmission of set-up data from the outstation being introduced, wherein the set-up data is transmitted at a reduced rate relative to the normal operating rate.

Abstract: Extender apparatus for an optical network includes first and second extender units having an network-facing port for connection to a backhaul fiber and a subscriber-facing port for connection to a feeder fiber. Each extender unit includes a gain assembly and is operable selectively either in an enabled state, in which the gain assembly amplifies a signal received at either port of the extender unit and couples it to the other port of the extender unit, or in a disabled state, in which the gain assembly blocks coupling of a signal from either port of the extender unit to the other port of the extender unit. A failover unit is operable when the first extender unit is in the enabled state and the second extender unit is in the disabled state to detect occurrence of at least one fault condition in the first extender unit. The failover unit is responsive to the fault condition in the first extender unit to switch the first extender unit to the disabled state and the second extender unit to the enabled state.

Abstract: A PON in which parallel optical fiber paths are provided between dual OLTs and the ONTs, one of the optical fiber paths providing an active connection and the other optical fiber path providing a standby connection. Respective VLANs may be formed over the parallel optical fiber paths. If performance indicators, for example Ethernet continuity check messages, indicate that an ONT is no longer in communication with the OLT then data may be sent via the VLAN associated with the standby connection.

Abstract: A PON in which parallel optical fibre paths are provided between dual OLTs and the ONTs, one of the optical fibre paths providing an active connection and the other optical fibre path providing a standby connection. Respective VLANs may be formed over the parallel optical fibre paths. If performance indicators, for example Ethernet continuity check messages, indicate that an ONT is no longer in communication with the OLT then data may be sent via the VLAN associated with the standby connection.

Abstract: The present invention relates to the introduction of an outstation into an optical network. The optical network has a central station, and a plurality of previously introduced outstations which are optically connected to the central station. The network is operable in: a normal operating state in which data traffic is received from previously introduced outstations at a normal data rate; and, a set-up state in which the transmission of data traffic from the previously introduced outstations is restricted relative to the normal state, the method including the step of: when the network is in the set-up state, performing a set-up operation for introducing the outstation into the optical network, the set-up operation involving the transmission of set-up data from the outstation being introduced, wherein the set-up data is transmitted at a reduced rate relative to the normal operating rate.

Abstract: Extender apparatus for an optical network includes first and second extender units having an network-facing port for connection to a backhaul fiber and a subscriber-facing port for connection to a feeder fiber. Each extender unit includes a gain assembly and is operable selectively either in an enabled state, in which the gain assembly amplifies a signal received at either port of the extender unit and couples it to the other port of the extender unit, or in a disabled state, in which the gain assembly blocks coupling of a signal from either port of the extender unit to the other port of the extender unit. A failover unit is operable when the first extender unit is in the enabled state and the second extender unit is in the disabled state to detect occurrence of at least one fault condition in the first extender unit. The failover unit is responsive to the fault condition in the first extender unit to switch the first extender unit to the disabled state and the second extender unit to the enabled state.

Abstract: An optical signal transmission apparatus for transmitting a plurality of data signals comprising a plurality of inputs for receiving a respective one of the data signals and delivering the respective data signal with a controlled phase and at a controlled data rate. A plurality of optical carrier signals having different wavelength is generated. Each of a plurality of first modulators is operative for modulating a respective one of the optical carriers with a respective data signal to provide a first-modulated optical carrier signal. An optical signal-routing device has a plurality of input ports, each port being for receiving a respective one of the first-modulated optical carrier signals and delivering it to the output port of the device.

Abstract: An optical signal transmission apparatus for transmitting a plurality of data signals comprising a plurality of inputs for receiving a respective one of the data signals and delivering the respective data signal with a controlled phase and at a controlled data rate. A plurality of optical carrier signals having different wavelength is generated. Each of a plurality of first modulators is operative for modulating a respective one of the optical carriers with a respective data signal to provide a first-modulated optical carrier signal. An optical signal-routing device has a plurality of input ports, each port being for receiving a respective one of the first-modulated optical carrier signals and delivering it to the output port of the device.

Abstract: An optical pulse source includes a gain-switched semiconductor laser diode. Light from a continuous wave source is opitically coupled into the laser cavity. Light output from the laser cavity passes through an electro-optic amplitude modulator. Synchronized modulating signals are applied to the semiconductor diode and to the amplitude modulator. The source outputs short low-jitter low-pedestal optical pulses and is suitable for use, for example, in a broadband optical network operating at thigh bit rates of 100 Gbit/s or more, or in an optical interconnect.

Abstract: A semiconductor optical amplifier has an optical path from its input to its output through an optical amplification region, the path having a length that exceeds 1 mm. In use, the amplifier is fed at its input with a modulated optical signal that is modulated at a given bit rate, and a target wave, so that the amplifier produces modulation of the target wave according to the modulation of the optical signal. The path length is selected to be longer than that at which optical saturation occurs. The gain of the amplifier exhibits a −3 db bandwidth that extends beyond 20 GHz in respect of the modulation bit rate. The amplifier may also be used for four wave mixing.

Abstract: An optical AND gate includes at least one semiconductor laser amplifier (SLA) and inputs for first and second optical signals. The gate produces an output corresponding to the AND product of A and B. In one aspect of the invention, the first and second signals are equal in wavelength. The gate may comprise a single SLA which receives the first signal A together with a third signal P, which may be a continuous wave pump. The second signal B is input in an orthogonal polarization state to A and P. Alternatively, the gate may comprise a pair of SLAs. A first SLA receives the first signal A together with the pump P. A sideband is selected from the output of the first SLA and input to the second SLA together with the second signal B. A sideband is selected from the output of the second SLA corresponding to the AND product C of A and P with B.

Abstract: Radio frequency modulated optical radiation is generated for use in a radio over fibre communications system. A semiconductor electroabsorption modulator efficiently modulates an input optical signal at harmonics of the electrical modulation frequency applied to the electroabsorption modulator. A low frequency design, and thus low cost, electroabsorption modulator is utilized to generate higher order harmonics of an electrical drive signal for use in a radie over fibre communications systems.

Abstract: An optical pulse source includes a gain-switched semiconductor laser diode (1). Light from a continuous wave source (3) is optically coupled into the laser cavity. Light output from the laser cavity passes through an electro-optic amplitude modulator (2). Synchronised modulating signals are applied to the semiconductor diode and to the amplitude modulator. The source outputs short low-jitter optical pulses and is suitable for use, for example, in a broadband optical network operating at high bit rates of 100 Gbit/s or more, or in an optical interconnect.