Tapped delay line based gain flattening filter
First Claim
1. An apparatus for changing the spectral profile of an optical signal comprising:
- a plurality of optical paths, each of said optical paths having associated therewith a delay element which imparts a predetermined delay to a signal propagating through the optical path;
a plurality of couplers configured to split the optical signal among said plurality of optical paths according to predetermined splitting ratios;
wherein said predetermined delays and predetermined splitting ratios are chosen so as to effect the desired change to said spectral profile.
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Abstract
A method of modifying the spectral distribution of an optical signal includes the steps of splitting the signal among a plurality of optical paths, delaying the propagation of the signal through one or more of the optical paths by a time duration which results in the desired spectral distribution when the signals at the output ends of each optical path are recombined, and then recombining those outputs. An apparatus for changing the spectral profile of an optical signal includes an input waveguide and a plurality of tapped delay lines. Each of the tapped delay lines has a delay element configurable to impart a predetermined delay to the signal propagating down the delay line. Couplers split an optical signal, propagating on the input waveguide, among the tapped delay lines. The delays imparted to the signals on each line are chosen so as to effect the desired change to the spectral profile.
21 Citations
25 Claims
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1. An apparatus for changing the spectral profile of an optical signal comprising:
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a plurality of optical paths, each of said optical paths having associated therewith a delay element which imparts a predetermined delay to a signal propagating through the optical path;
a plurality of couplers configured to split the optical signal among said plurality of optical paths according to predetermined splitting ratios;
wherein said predetermined delays and predetermined splitting ratios are chosen so as to effect the desired change to said spectral profile. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18)
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14. A gain flattening filter for use with an optical amplifier comprising:
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an input waveguide;
a plurality of tapped delay lines comprising waveguides and delay elements associated with said waveguides, a plurality of variable couplers configured to split an optical signal propagating on said input waveguide among said plurality of tapped delay lines according to predetermined splitting ratios;
wherein each of said delay elements is configurable to impart a predetermined delay to the signal propagating down the associated waveguide, wherein said predetermined delays are chosen so as to effect a flattening of the spectral profile of said optical signal.
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19. An optical communication system comprising:
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an optical amplifier;
a spectral filter comprising an input waveguide;
a plurality of tapped delay lines, each of said tapped delay lines including a delay element on said line, a plurality of couplers configured to split an optical signal propagating on said input waveguide among said plurality of tapped delay lines according to predetermined splitting ratios;
wherein said delay elements are configurable to impart a predetermined delay to the signal propagating down said line, wherein said predetermined delays are chosen so as to effect the desired change to said spectral profile; and
an optical path between said amplifier and said filter.
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20. A method for modifying the spectral distribution of an optical signal comprising the steps of:
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splitting the signal among a plurality of optical paths, each having an output end, whereby a portion of the signal propagates on each of the optical paths;
changing the relative phases of the portions of the signal propagating through the optical paths;
modifying the amplitudes of the portions of the signal propagating through the optical paths;
the relative phase changes and the amplitude modifications having magnitudes which result in a desired spectral distribution when the portions of the signal at the output ends of the optical paths are combined; and
combining the portions of the signal at the output ends of the optical paths. - View Dependent Claims (21, 22, 23, 24)
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25. A method for modifying the spectral distribution of an optical signal comprising the steps of:
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splitting the signal among a plurality of optical paths having output ends according to predetermined splitting ratios, changing the relative phases of the portions of the signal propagating through different ones of the optical paths;
the relative phase changes and the splitting ratios having magnitudes which result in a desired spectral distribution when the portions of the signal at the output ends of the optical paths are combined; and
combining the portions of the signal at the output ends of the optical paths.
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Specification