Optical Power Control via Laser Wavelength Tuning
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Solution Overview
Problem
In optical communications networks, particularly in Passive Optical Networks (PONs), controlling the power of optical signals within the dynamic range of receivers is challenging due to unknown system losses and the need for cost-effective solutions without expensive monitoring and control devices, leading to issues like receiver overload and attenuation variations.
Innovation Solution
A method and apparatus that utilize a laser and bandpass filter to adjust the optical signal's wavelength based on received power level information, allowing for per-channel power control without adding active components, using a controller circuitry and memory to tune the laser output wavelength and communicate power level information through an in-band channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual fixed attenuators are used to control optical power, then the receiver power level can be adjusted, but the operation becomes time-consuming and error-prone
Solution Approach 1:
The system performs automatic power control without requiring manual intervention from field engineers. The OLT automatically measures received power levels and adjusts laser wavelength to maintain optimal power at the receiver, eliminating manual attenuator installation and verification tasks.
Solution Approach 2:
The system continuously monitors the received optical power level and uses this feedback information to automatically adjust the laser wavelength. The OLT measures power levels, compares them against target values, and tunes the laser accordingly to maintain proper power distribution throughout the network.
2Reliability
If field engineers install attenuators to fix power issues, then the power level can be corrected initially, but problems arise during system ageing due to attenuation variations
Solution Approach 1:
Instead of using static manual attenuators, the system employs dynamic wavelength tuning of the laser. The laser wavelength can be continuously adjusted in response to changing network conditions, allowing the system to adapt to attenuation variations during ageing rather than relying on fixed attenuator settings.
Solution Approach 2:
The system continuously monitors power levels and automatically adjusts laser wavelength to compensate for changes over time. This feedback mechanism ensures that power levels remain optimal throughout the system lifecycle, eliminating the need for manual reconfiguration during ageing.
3Reliability
If transmitter power control is implemented, then the optical power can be adjusted, but the transceiver cost increases and manufacturing complexity increases
Solution Approach 1:
The system controls optical power by changing the laser wavelength parameter rather than adjusting transmitter power directly. This approach uses the wavelength-dependent response of the bandpass filter to achieve power control, avoiding the need for complex power adjustment mechanisms in the transceiver.
Solution Approach 2:
The bandpass filter acts as an intermediary element that converts wavelength changes into power adjustments. By tuning the laser wavelength relative to the filter's passband, the system achieves power control without direct transmitter power adjustment, simplifying the transceiver design.
4Adaptability or versatility
If in-line VOA is added to control power, then per-channel power control is achieved, but the network complexity increases and active components are introduced
Solution Approach 1:
The system uses the existing laser wavelength tuning capability for multiple purposes: both for channel selection and for power control. This multi-functionality eliminates the need for separate power control components, achieving per-channel power control without adding active elements to the network.
Solution Approach 2:
The bandpass filter serves as an intermediary that enables power control through wavelength tuning. By exploiting the filter's wavelength-dependent characteristics, the system achieves power adjustment without requiring active variable attenuators, maintaining network simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables automated power control without hardware modifications, eliminates the need for attenuators and transmitter power control, and provides independent channel attenuation, improving serviceability and reducing costs while maintaining acceptable signal quality.
Implementation Method 1
a laser for transmitting an optical signal to the first network element
Implementation Method 2
a bandpass filter operating on the optical signal produced by said laser
Data Source
AI summary
A method of power control of an optical signal transmitted by a first network element. The first network element comprising a laser and a bandpass filter operating on the optical signal produced by said laser, whereas the method comprises receiving (106) information indicative of a power level of the optical signal transmitted by the first network element; and tuning (110) the laser output wavelength in response to said received information.