Optical waveguide amplifiers
AssigneeNorthern Telecom Limited
InventorsMaurice O'Sullivan, Jonathan P. King, Andrew N. Robinson
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Abstract
An optical amplifier for use in a WDM transmission system has a circulator two of whose ports constitute the input and output ports of the amplifier, and to whose third port is connected an optically amplifying fibre. Bragg grating reflectors are formed at specific intervals along this fibre chosen such that each WDM channel is reflected back to the circulator at a distance in inverse proportion to the gain per unit length experienced by that channel in the amplifier fibre, whereby all channels are amplified by the amplifier to the same extent.
Claims16
An optical waveguide amplifier, which amplifier includes an optical circulator having input, intermediate and output ports, wherein the input port is optically coupled non-reciprocally to the intermediate port and the intermediate port is optically coupled to the output port, wherein the input and output ports of the circulator respectively constitute input and output ports of the amplifier, and wherein a length of optical amplifier waveguide is optically coupled with the intermediate port of the circulator, which amplifier waveguide is provided with a plurality of spectrally selective reflectors optically in series in a manner providing active sections of the optical amplifier waveguide lying between consecutive pairs of said reflectors, wherein the reflection bands of the reflectors are spectrally separated by intervening guard bands.
A wavelength division multiplexed (WDM) transmission system having a plurality of optical amplifiers optically in series, of which at least one optical amplifier is of a construction in which the WDM signal input thereto is directed from an optical circulator into one end of a length of optical amplifier waveguide, wherein different wavelength components of the signal are reflected at different distances along the amplifier waveguide from the circulator, whereby said components are amplified in a ratio that is different from the ratio of the gains per unit length of the amplifier waveguide afforded to said wavelength components which components are spectrally separated by intervening guard bands.
A method of optically amplifying a set of wavelength division multiplexed signal channels, said set consisting of a set of mutually exclusive sub-sets, each of at least one signal channel, wherein different members of the set of subsets of channels are caused to propagate for different distances along a length of optically amplifying waveguide common to all members of the set from one end of the optically amplifying waveguide before being reflected back to said one end at different ones of a set of spectrally selective reflectors having reflective wavebands that are spectrally separated by intervening spectral guard bands.
Dependencies are inferred from the claim text.