Abstract: Optical modules as used in various types of communication systems are formed to include a flexible substrate to support various optical, electronic, and opto-electronic module components in a manner that can accommodate various packaging constraints. The flexible substrate is formed of a polyimide film is known to exhibit excellent electrical isolation properties, even though the films are generally relatively thin (on the order of 10-100 ?ms, in most cases). The flexible polyimide film is sized to accommodate the constraints of a given package “footprint”; more particularly, sized to fit an open ‘floor area’ within package, allowing for a populated film to be placed around various other “fixed-in-place” elements . The polyimide film is easily cut and trimmed to exhibit whatever topology is convenient, while providing enough surface area to support the affixed components and associated optical fiber traces.

Abstract: An optical amplifier module is configured as a multi-stage free-space optics arrangement, including at least an input stage and an output stage. The actual amplification is provided by a separate fiber-based component coupled to the module. A propagating optical input signal and pump light are provided to the input stage, with the amplified optical signal exiting the output stage. The necessary operations performed on the signal within each stage are provided by directing free-space beams through discrete optical components. The utilization of discrete optical components and free-space beams significantly reduces the number of fiber splices and other types of coupling connections required in prior art amplifier modules, allowing for an automated process to create a “pluggable” optical amplifier module of small form factor proportions.

Abstract: A doped fiber amplifier (e.g., an erbium-doped fiber amplifier—EDFA) module is configured to include metrology functionality for performing real-time measurements of the fiber spans connected to the EDFA. In one embodiment, a separate component utilized to perform optical time domain reflectometry (OTDR) measurements is embedded with the EDFA module. The OTDR measurement component includes its own laser source and detector, which are used to analyze the input and output fiber spans associated with the EDFA. In another embodiment, the pump laser of the EDFA is also used as the optical probe light source for the OTDR component, where the source is either “switched” or “shared” between performing amplification and providing OTDR measurements. In yet another embodiment, a “dual pump” source is included with the OTDR component itself and modified to utilize one laser for amplification and the other for OTDR purposes.

Abstract: A light source assembly (300) for emitting depolarized light, and comprising: at least one light source (312) configured to emit substantially polarized light; and a light depolarizer (318) arranged to receive light from the light source and comprising a high birefringence optical fiber having a longitudinal core and orthogonal birefringent axes having an angular displacement around the core that varies along the length of the fiber, wherein light emitted from the depolarizer comprises a plurality of polarization states.

Abstract: A method and apparatus for monitoring and controlling an optical node 100. The optical node 100 including one or more optical components 120, 121 or 122 connected by optical fiber carrying an optical signal 102. The optical signal 102 including a plurality of optical channels. A set of measurement sequences is determined, each measurement sequence defining a set of optical channels from the plurality of optical channels and a measuring sequence for measuring an optical property of the set of optical channels. A measurement sequence is selected from the set of measurement sequences based on the operating conditions of the optical node 100. The optical properties of the set of optical channels of the selected measurement sequence are measured. The measured optical properties are analyzed to determine whether one or more optical components 120, 121 or 122 are causing the optical node 100 to operate outside the tolerance of a defined set of operating conditions.

Abstract: An OTDR system utilizes a laser source that is turned “on” and kept powered until its light reaches the end of the fiber span being measured (i.e., until the fiber span is fully illuminated). At any point in time after the fiber is fully illuminated, the laser source can be turned “off”. The return (reflected and backscattered) signal is directed into a photodetector of the OTDR, and is measured from the point in time when the fiber span starts to be illuminated. The measurements are made by sampling the return signal at predetermined time intervals—defined as the sampling rate. The created power samples are then subjected to post-processing in the form of a differentiation operation to create a conventional OTDR trace from the collected data.

Abstract: A light source assembly (300) for emitting depolarized light, and comprising: at least one light source (312) configured to emit substantially polarized light; and a light depolarizer (318) arranged to receive light from the light source and comprising a high birefringence optical fibre having a longitudinal core and orthogonal birefringent axes having an angular displacement around the core that varies along the length of the fibre, wherein light emitted from the depolarizer comprises a plurality of polarization states.

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.