WDM Comb Source Optical Link Power Optimization
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Solution Overview
Problem
Wavelength division multiplexed (WDM) optical links face challenges in reducing power consumption and optimizing the use of optical amplifiers, as existing systems either require multiple bulky and expensive lasers or suffer from power loss due to the amplification of all generated lines simultaneously, leading to limited link budget and increased power consumption.
Innovation Solution
A transmitter design that uses a comb source to generate multiple discrete lines, where only modulated lines are routed to optical amplifiers, allowing for better allocation of scarce amplifier power and utilizing frequency selective modulators and optical filters to block unmodulated lines, thereby reducing power waste and enhancing power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single comb source is used to generate all frequencies simultaneously, then the transmitter size and cost are reduced, but the link budget is limited due to power loss during modulation and interfaces
Solution Approach 1:
The comb source spectrum is segmented into multiple frequency groups, with only the required frequency lines being extracted and modulated. This segmentation allows the system to use a compact comb source while minimizing power loss by avoiding modulation of unnecessary frequency lines, thus improving the link budget.
Solution Approach 2:
Specific frequency lines are extracted from the comb source spectrum using frequency selective elements. This extraction ensures that only the necessary frequency components are processed and transmitted, reducing power consumption and improving the link budget while maintaining a compact transmitter structure.
2Ease of operation
If optical amplifiers amplify all generated lines simultaneously, then the amplification process is simplified, but power consumption increases and the link budget is limited
Solution Approach 1:
Only the modulated frequency lines that require amplification are extracted and routed to the optical amplifier. This selective amplification reduces power consumption compared to amplifying all comb source lines, while still providing the necessary signal boosting for the transmitted channels.
Solution Approach 2:
The optical amplifier provides localized amplification only to the specific frequency lines that are being transmitted, rather than uniformly amplifying the entire spectrum. This local quality approach optimizes power usage by concentrating amplification resources where they are actually needed.
3Manufacturing precision
If frequency selective modulators are used to modulate individual channels, then channel selectivity is improved, but additional power consumption is required for active tuning
Solution Approach 1:
The frequency selective modulators are designed to operate at fixed, predetermined frequencies without requiring active tuning during operation. This self-service approach eliminates the power consumption associated with tuning mechanisms while maintaining high channel selectivity through the inherent frequency selectivity of the modulators.
4Reliability
If EDFAs are used for optical amplification, then data distortion is avoided, but the devices become bulky, expensive and power hungry
Solution Approach 1:
Semiconductor optical amplifiers are used instead of EDFAs, providing a more compact, cost-effective, and power-efficient solution. While EDFAs offer excellent data integrity, the semiconductor amplifiers provide sufficient performance for the application while dramatically reducing the physical size, cost, and power consumption of the amplification stage.
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 approach reduces power consumption by optimizing the use of optical amplifiers, improving the link budget, and increasing the range and reliability of the WDM optical link while maintaining data integrity.
Implementation Method 1
a light source generates a plurality of discrete lines with different frequencies
Implementation Method 2
a comb source generating more than one comb line and having a free spectral range
Implementation Method 3
more than one frequency selective modulators sharing an input bus waveguide and modulating comb lines generated by the comb source
Implementation Method 4
utilizing frequency selective modulators and optical filters to block unmodulated lines
Implementation Method 5
a first semiconductor optical amplifier wherein a subset of the more than one comb lines is filtered out by one out of an optical filter comprising coupled resonators or frequency selective modulators operated in drop configuration
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 1e~1f
AI summary
A receiver (RX) for an optical link configured to decode at least one data stream (c1-c4) from an optical signal (IN) transmitted by a transmitter (TX) of the optical link, wherein the optical signal (IN) comprises a plurality of optical carriers with different frequencies (f) and a plurality of the optical carriers have been modulated according to a data stream (c1-c4) by respective modulators (FSM, RRM, MZM), wherein the receiver (RX) comprises a polarization splitting element (PSC) with one input port and two output ports, at least one resonant add-drop multiplexer (ADM) tuned to at least one optical carrier modulated according to a data stream (c1-c4), and at least one detector (PD) to convert a light intensity into an electrical signal, wherein light from the two output ports of the polarization splitting element (PSC) is coupled into the resonant add-drop multiplexer (ADM) in opposite directions, and that light is coupled from the resonant add-drop-multiplexer (ADM) to the at least one detector (PD) in two opposite directions.