Bidirectional Optical Module Using Periodical Filters
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Solution Overview
Problem
Current bidirectional optical communication systems face challenges in efficiently managing high channel densities within limited spectral bands, often requiring multiple fibers or expensive multiplexers/demultiplexers, especially when accommodating 80 eastbound/westbound optical signals with 100 GHz spacing.
Innovation Solution
The implementation of a bi-directional communication system with local multiplexers/demultiplexers, wavelength monitors, and centralized controllers, which utilize narrowband cyclic or periodical filters to pair eastbound and westbound channels closely, allowing all 80 channels to be accommodated within the C-band without replacing existing 100 GHz multiplexers/demultiplexers, using a single bidirectional optical fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If channel spacing is reduced to 50 GHz to accommodate all 80 eastbound/westbound optical signals in the C-band on a single bidirectional optical fiber, then all signals can be accommodated within the C-band, but 50 GHz multiplexer/demultiplexer is more costly than 100 GHz multiplexer/demultiplexer
Solution Approach 1:
The patent combines eastbound and westbound channels into a single bidirectional optical fiber using wavelength division multiplexing. By pairing eastbound channels (e.g., 1550.12 nm) with corresponding westbound channels (e.g., 1550.22 nm) at 100 GHz spacing, the system accommodates 80 total channels without requiring expensive 50 GHz multiplexers/demultiplexers, thus merging bidirectional traffic efficiently while controlling component costs.
2Quantity of substance
If channel assignments are extended into the L-band in addition to the C-band to maintain 100 GHz channel spacing for 80 total eastbound/westbound optical signals, then channel spacing can be maintained, but a more extensive and expensive inventory of communication modules is required
Solution Approach 1:
The patent changes the wavelength parameter by pairing eastbound and westbound channels that are offset by 100 GHz (e.g., eastbound at 1550.12 nm paired with westbound at 1550.22 nm). This parameter adjustment allows both directions to coexist on the same fiber using the same C-band spectrum, eliminating the need to extend into the L-band and reducing module inventory requirements.
3Adaptability or versatility
If a 2-fiber WDM ring architecture is used to transmit eastbound and westbound optical signals on different optical fibers, then frequency channels can be re-used across the optical fibers, but two separate optical fibers are required
Solution Approach 1:
The patent merges eastbound and westbound optical signals onto a single bidirectional optical fiber using wavelength division multiplexing. By assigning paired wavelengths (e.g., 1550.12 nm for eastbound and 1550.22 nm for westbound) that are separated by 100 GHz, the system achieves frequency channel re-use while reducing fiber quantity from two to one, thereby simplifying the physical infrastructure.
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 configuration enables a cost-effective and flexible architecture that accommodates high channel densities within the C-band, reducing the need for additional spectral bands and expensive inventory, while maintaining efficient signal transmission and reception.
Implementation Method 1
an optical filter that is transmissive to an outbound optical signal emitted by a transmitter and that reflects an inbound optical signal received from the optical fiber
Data Source
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AI summary
In an example, a communication module includes an optical transmitter, an optical receiver, and a periodical filter. The optical transmitter is configured to emit an outbound optical signal. The optical receiver is configured to receive an inbound optical signal. A first frequency of the outbound optical signal is offset from a second frequency of the inbound optical signal by an amount less than a channel spacing of a multiplexer/demultiplexer implemented in an optical communication system that includes the communication module. The periodical filter is positioned in optical paths of both the outbound optical signal and the inbound optical signal and has a transmission spectrum with periodic transmission peaks and troughs. The first frequency of the outbound optical signal may be aligned to one of the transmission peaks and the second frequency of the inbound optical signal may be aligned to one of the transmission troughs, or vice versa.