Back to results
US 2003/0147125 A1Published application
Gain control in optical amplifiers
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsJohan Sandell, Edgard Goobar, Sven Wingstrand
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsJohan Sandell, Edgard Goobar, Sven Wingstrand
Estimating the term…
An optical amplifier arrangement is provided that includes an amplifier (10) elements for measuring the gain applied to the total input power (21, 31, 40) and a control unit (50) adapted to determine the degree of variation of gain with wavelength. i.e. the gain tilt, on the basis of a measurement of total gain. This is achieved by using a predetermined relationship between the wavelength dependent gain variation and total gain. This relationship is determined on production by measurement of the amplifier or of a batch or class of amplifiers. In this way a precise figure for gain tilt is provided for each amplifier. This may be used to eliminate gain tilt. Alternatively, if the system requirements tolerate limited gain tilt, the figure may be used to monitor the system.
An optical amplifier arrangement for amplifying input signals within a predetermined wavelength band including an optical amplifier (10), means (21, 40) for measuring the input power to the optical amplifier, means (31, 40) for measuring the output power from the amplifier, and means (40) for determining total amplifier gain from said input and output powers, characterised by means (50) for determining the degree of variation of gain with wavelength using a predetermined relationship between total gain and the slope of gain with wavelength.
An arrangement as claimed in claim 2, characterised in that said predetermined relationship models the slope of gain with wavelength against the deviation of actual amplifier gain from a known optimal gain value at which amplifier gain is substantially equal for all wavelengths in said wavelength band, and including means (50) for determining the deviation of said determined gain from said optimal gain value.
An optical amplifying device including first (100) and second (110) optical amplifiers and attenuating means (120) connected between said first and second optical amplifiers, characterised by means (130) for measuring the gain of each amplifier, means (130) for determining for each optical amplifier the degree of variation of gain with wavelength using a predetermined relationship between total amplifier gain and the slope of gain with wavelength, means (130) for adjusting the pump power to said first amplifier (100) and/or the attenuation of said attenuator (130) and/or the pump power to said second optical amplifier (120) to adjust the gain of at least one of said amplifiers.
An optical transmission link of an optical fibre network adapted to carry wavelength division multiplexed signals, said link including an optical fibre for carrying traffic data in at least one direction and at least one optical amplifier coupled to said optical fibre for amplifying the signal power of said traffic data, characterised in that said amplifier includes means for measuring total amplifier gain and means for determining the degree of variation of gain with wavelength from a predetermined relationship between total amplifier gain and the slope of gain with wavelength.
A method for determining the degree of variation of gain with wavelength applied to optical WDM signals amplified in an optical amplifier, including:
Dependencies are inferred from the claim text.