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US 6,445,493 B1Granted
Balanced gain flattening filters
AssigneeCorning Incorporated
InventorsGlenn E. Kohnke, Qi Wu
Life of this patent
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Abstract
Compound gain flattening filters of optical amplification include a series of filter components with spectral responses that are combined to approach a target loss spectrum. Small variations in the central wavelengths of the component responses can produce large errors in the combined response of the compound gain flattening filter. However, the components can be divided into sub-components with balanced central wavelength deviations to achieve the desired response goals despite exhibiting otherwise detrimental wavelength deviations.
Claims61
A compound gain flattening filter comprising:
- at least first and second sets of filter sub-components together approximating a single set of filter components defined by a best fit algorithm that determines central wavelengths of response for the filter components to approach a desired spectral filter response;
- at least one sub-component of said first set exhibiting a central wavelength of response shifted in a positive direction from the central wavelength of a corresponding component determined by the best fit algorithm;
- at least one sub-component of said second set exhibiting a central wavelength of response shifted in a negative direction from the central wavelength of the same corresponding component determined by the best fit algorithm;
- and
- said at least first and second sets being combined for producing an actual spectral filter response that is closer to the desired filter response than a filter response of the single set of filter components in which the corresponding filter component exhibits an actual central wavelength similarly shifted in either direction from the central wavelength determined by the best fit algorithm.
2 more elements
A compound gain flattening filter of an optical amplification system comprising:
- a series of filter components that produce a combined filter response approximating a desired spectral filter response;
- each of said filter components exhibiting a substantially different filter component response than other of said components of the series;
- said one component being divided into at least two sub-components having similar response profiles that are summed for producing one of the different filter component responses;
- and
- said response profiles of the sub-components being relatively shifted in wavelength in opposite directions to better approximate the desired spectral filter response than if the filter component response of the one component were similarly shifted in a single direction.
2 more elements
An optical amplifying system comprising:
- an optical amplifier exhibiting a variation in gain over a domain of wavelengths;
- a pair of first and second filters exhibiting substantially similar response profiles that contribute to reducing the variation in gain over the domain of wavelengths;
- each of said first and second filters exhibiting at least one peak wavelength of loss that differs from a common peak wavelength of loss that minimizes the variation in gain with a single filter;
- and
- said peak wavelengths of the first and second filters being offset in opposite directions from the common peak wavelength for reducing the variation in gain with respect to a similar offset of the peak wavelengths in the same direction from the common peak wavelength.
2 more elements
An optical amplifying system comprising:
- an optical amplifier exhibiting a variation in gain over a domain of wavelengths;
- a plurality of pairs of long period gratings;
- each pair including two long period gratings that exhibit spectral responses with central wavelengths matched to a desired central wavelength of the pair for reducing gain variations of the optical amplifier;
- one long period grating member of each pair belonging to one of two similar sets of long period gratings and the other long period grating member of each pair belonging to the other of the two similar sets of long period gratings;
- and
- said central wavelengths of the two long period gratings of a first of said pairs being offset in opposite directions with respect to the desired central wavelength for reducing the variation in gain with respect to similar offsets of said central wavelengths in the same direction with respect to the desired central wavelength.
3 more elements
The system of clam 23 in which the long period grating members of each set are offset in the same direction.
A method of reducing gain variation in an optical amplification system comprising the steps of:
- determining a desired filter loss spectrum;
- fitting the desired filter loss spectrum with a series of filter components having individual spectral responses centered at different specified wavelengths;
- fashioning at least a first of the filter components from at least two filter sub-components with similar spectral responses;
- and
- arranging the filter sub-components so that the central wavelengths of the two filter sub-components are offset in opposite directions with respect to the specified wavelength of the first filter component for better matching the desired loss spectrum despite variations in the central wavelengths of the filter sub-components.
2 more elements
A method of making a compound gain flattening filter comprising the steps of:
- approximating a predetermined filter loss spectrum with a plurality of spectral response profiles having prescribed central wavelengths;
- fabricating a plurality of filter components having similar response profiles and central wavelengths that at least approximately correspond to the prescribed central wavelengths;
- and
- forming at least a first of the filter components with at least two filter sub-components having similar response profiles and central wavelengths that are offset in opposite directions from the prescribed central wavelength of the first filter component.
1 more element
A compound optical filter comprising:
- at least first and second sets of filter sub-components together approximating a single set of filter components defined by a best fit algorithm that determines central wavelengths of response for the filter components to approach a desired spectral filter response;
- at least one sub-component of said first set exhibiting a central wavelength of response shifted in a positive direction from the central wavelength of a corresponding component determined by the best fit algorithm;
- at least one sub-component of said second set exhibiting a central wavelength of response shifted in a negative direction from the central wavelength of the same corresponding component determined by the best fit algorithm;
- and
- said at least first and second sets being combined for producing an actual spectral filter response that is closer to the desired filter response than a filter response of the single set of filter components in which the corresponding filter component exhibits an actual central wavelength similarly shifted in either direction from the central wavelength determined by the best fit algorithm.
2 more elements
A compound optical filter comprising:
- a series of filter components that produce a combined filter response approximating a desired spectral filter response;
- each of said filter components exhibiting a substantially different filter component response than other of said components of the series;
- said one component being divided into at least two sub-components having similar response profiles that are summed for producing one of the different filter component responses;
- and
- said response profiles of the sub-components being relatively shifted in wavelength in opposite directions to better approximate the desired spectral filter response than if the filter component response of the one component were similarly shifted in a single direction.
2 more elements
Dependencies are inferred from the claim text.