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AssigneeFujitsu Limited
InventorsShinya Inagaki, Norifumi Shukunami, Susumu Kinoshita, Hiroyuki Itou, Taiki Kobayashi
Estimating the term…
An optical amplification device which includes first and second optical amplifiers, and a controller. The first optical amplifier receives a light and amplifies the received light. The second optical amplifier receives the light amplified by the first optical amplifier, and amplifies the received light. When a level of the light received by the first optical amplifier changes by Δ, the controller controls a level of the light received by the second optical amplifier to change by approximately −Δ. In various embodiments, the controller causes the sum of the gains of the first and second optical amplifiers to be constant. In other embodiments, the optical amplification device includes first and second optical amplifier and a gain adjustor. The gain adjustor detects a deviation in gain of the first optical amplifier from a target gain, and adjusts the gain of the second optical amplifier to compensate for the detected deviation.
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Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
In a multiwavelength system, e.g. gain equalisation: using automatic gain control [AGC]
Fibre amplifiers: tandem amplifiers
Stabilisation of laser output parameters, e.g. frequency or amplitude: in optical amplifiers
In which processing or amplification is carried out without conversion of the main signal from optical form: characterised by the medium used for…
Term ended 9 Mar 2019 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to cascaded optical amplifiers and, more particularly, to gain and signal level adjustments of cascaded optical amplifiers.
2. Description of the Related Art
These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a diagram illustrating an optical fiber communication system, according to an embodiment of the present invention.
FIG. 2 is a graph illustrating a gain tilt occurring in an optical amplifier.
Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.
FIG. 1 is a diagram illustrating an optical fiber communication system, according to an embodiment of the present invention. Referring now to FIG. 1, the system includes a first terminal station 102, a second terminal station 104, an optical fiber transmission line 106 connecting terminal stations 102 and 104, and a plurality of optical repeaters 108 arranged along optical fiber transmission line 106. Each optical repeater 108 includes an optical amplifier 110 optically connected to optical fiber transmission line 106. Although FIG. 1 shows two optical repeaters 108, more than two optical repeaters can be used, depending on the system design parameters. Further, in some systems, a single optical repeater may be used.
First terminal station 102 includes a plurality of optical transmitters (TX) 112 (#1 to #N) respectively outputting a plurality of optical signals having different wavelengths. An optical multiplexer (MUX) 114 wavelength division multiplexes the optical signals output from optical transmitters 112 (#1 to #N) to obtain WDM signal light. An optical amplifier (postamplifier) 116 amplifies the WDM signal light obtained from optical multiplexer 114 to output an amplified WDM signal light to optical fiber transmission line 106.