Variable Attenuator Control for Wavelength Signal Spectral Narrowing
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Solution Overview
Problem
In optical multiplexing, variable attenuators have limited wavelength granularity, leading to deficient or excessive attenuation in slots containing two adjacent signal components, which degrades signal quality due to spectral narrowing and surplus.
Innovation Solution
An optical transmission apparatus with a variable attenuator, spectrum monitor, calculation unit, and control unit that adjusts attenuation based on spectral narrowing and surplus to minimize spectral narrowing while allowing spectral surplus within a permissible range, optimizing signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single target value is used in a single control slot of a variable attenuator, then the control is simple, but the amount of attenuation becomes deficient or excessive when two signal components are included in the same wavelength band, degrading signal quality
Solution Approach 1:
The invention segments the control slot into multiple independent control regions corresponding to different signal components. Instead of applying a single attenuation value to the entire control slot, the system divides it into first and second control regions, each with its own target value, allowing precise independent control of attenuation for each signal component within the slot.
Solution Approach 2:
The invention implements local quality by assigning different attenuation characteristics to different parts of the control slot. Each signal component (first and second signal components) receives a customized target value based on its specific requirements, rather than applying a uniform attenuation across the entire slot, thereby optimizing signal quality locally for each component.
2Device complexity
If the wavelength granularity of the variable attenuator is limited, then the device complexity is reduced, but the signal quality degrades due to spectral narrowing and surplus in slots containing two adjacent signal components
Solution Approach 1:
The invention resolves the granularity limitation by introducing a new dimension of control - dividing the control slot into multiple control regions along the spectral dimension. This allows the system to achieve fine-grained attenuation control not by increasing the physical granularity of the attenuator, but by creating virtual segmentation through calculation and control logic, thereby maintaining signal quality without increasing device complexity.
Data Source
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AI summary
An optical transmission apparatus includes a variable attenuator configured to adjust output intensity of each wavelength signal included in a multiplexed optical signal having been input; a monitor configured to measure an output spectrum of the variable attenuator; a calculation unit configured to calculate an amount of spectral narrowing and an amount of spectral surplus, based on a measured value by the monitor, and a target value set in advance; and a control unit configured to control an amount of attenuation of the variable attenuator, based on the amount of spectral narrowing and the amount of spectral surplus.