Abstract: An optical amplifier assembly for determining a parameter of an optical fibre configured to amplify an optical signal being propagated therethrough, the assembly comprising: at least one amplifier pump light source assembly configured to transmit light at a plurality of wavelengths into the optical fibre; a receiver configured to receive light that has propagated through at least part of the optical fibre; and a processor configured to determine the parameter of the optical fibre based on the received light.

Abstract: A light source package is disclosed for a Raman amplifier node having a primary optical fiber for carrying an optical signal and a secondary optical fiber for carrying the optical signal when the signal is rerouted from the primary optical fiber. The light source package includes a primary light source for emitting light into the primary optical fiber when the optical signal is carried by the primary optical fiber to induce Raman gain of the optical signal, and a secondary light source for emitting light into the secondary optical fiber when the optical signal is carried by the secondary optical fiber to induce Raman gain of the optical signal.

Abstract: A tunable external cavity laser for use as a pump laser in an optical amplifier such as a Raman amplifier or erbium doped fibre amplifier comprising a semiconductor gain device (12) operable to provide light amplification, a diffraction grating (18) for selecting the wavelength of operation of the laser and a MEMs actuator for changing the selected wavelength. A plurality of gain devices can be coupled together to improve the bandwidth or gain of the optical amplifier.

Abstract: A light source package is disclosed for a Raman amplifier node having a primary optical fibre for carrying an optical signal and a secondary optical fibre for carrying the optical signal when the signal is rerouted from the primary optical fibre. The light source package includes a primary light source for emitting light into the primary optical fibre when the optical signal is carried by the primary optical fibre to induce Raman gain of the optical signal, and a secondary light source for emitting light into the secondary optical fibre when the optical signal is carried by the secondary optical fibre to induce Raman gain of the optical signal.

Abstract: A pump unit (402) for a Raman amplifier (400) including an optical fibre (401) carrying an optical signal (420) is disclosed. The pump unit includes at least two light sources (411, 412, 431, 432) for emitting light at different wavelengths into the fibre to induce Raman gain of the optical signal passing along the fibre, and a controller (409) for providing pulses to each of the light sources to control when they do and do not emit light. The controller is configured to control the width of the pulses to control the total power of the light emitted into the fibre.

Abstract: An optical amplifier system is provided which comprises first and second optical amplifiers (1, 2) for amplifying optical signals in a fibre optic communications link and a common pump (3) for optically pumping both the first amplifier (1) and the second amplifier (2) to effect such amplification. There is also provided an optical switch (6) for providing an optical path between the pump and the first amplifier in a first switching state and an optical path between the pump and the second amplifier in a second switching state to enable pumping of the first and second amplifiers by the pump sequentially. Advantageously this arrangement provides high accuracy to the outputs (4, 5) of the pump (3) and reduces low power pump noise.

Abstract: A plurality of semiconductor optical devices has a common package and common supporting structures and controls. The semiconductor optical devices are typically semiconductor lasers or photodiodes and are designed for operation independently of each other or in a coordinated way. In one embodiment, co-packaged semiconductor lasers may be used individually to drive each of the amplification stages of a multi-stage optical amplifier. The optical fibers connecting to the optical devices share a common port and are aligned prior to engagement with the light output/input of the co-packaged semiconductor optical devices.

Abstract: A variable gain optical amplifier comprises an EDFA for amplifying optical signals at different wavelengths and a pump driver 14 for optically pumping the EDFA to provide optical gain. An input detector 2 is provided for monitoring the power Pin of input signals to the EDFA, and an output detector 3 is provided for monitoring the power Pout of output signals from the EDFA. A gain control arrangement is provided for supplying a drive signal to the pump driver 14 to control the optical gain including a feed forward arrangement 20, 21, 22, 23 for supplying a feed forward signal dependent on the monitored input power Pin, and a feed back arrangement 5, 6, 7, 8, 9, 30 for supplying a feed back signal dependent on the monitored output power Pout.

Abstract: A multichannel optical amplifier having an adjustable gain set point is controlled to permit substantially constant gain tilt control during a gain set-point change so that the channel powers are maintained during system modification. To this end the amplifier comprises an erbium doped fibre (EDF) loop and associated pump amplifier for amplifying an optical signal comprising channels of different wavelengths, a variable optical attenuator (VOA) for controlling the gain of the amplifier by applying a loss profile that varies with wavelength so that the different channels are amplified in accordance with a required gain tilt, preferably a zero gain tilt, and a PI controller for applying a gain tilt adaptation profile to compensate for an inherent gain tilt to produce the required gain tilt.