Optical Frequency Comb WDM Without Precise Wavelength Control
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Solution Overview
Problem
Modern optical communication systems face high power consumption and cost issues due to precise wavelength control requirements for wavelength division multiplexing, which complicates dense deployment in data centers.
Innovation Solution
An optical transmitter using an optical frequency comb source with multiple optical paths of varying lengths to modulate light with different delays, combined without wavelength discrimination, allowing for colorless wavelength division multiplexing and enabling MIMO processing at the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wavelength-selective optical elements (colored MUX) are used for WDM, then wavelength channel multiplexing is achieved, but power consumption increases due to cooling and temperature-stabilization requirements
Solution Approach 1:
The patent extracts the wavelength-selective function from the multiplexing system by removing colored MUX elements. Instead of using wavelength-selective optical elements, the system uses a single-wavelength laser combined with optical frequency comb generation and MIMO processing to achieve wavelength division multiplexing functionality without the power-consuming temperature control infrastructure.
Solution Approach 2:
The patent replaces the mechanical/thermal control system (temperature-stabilized optical elements) with an electrical/optical processing system. By using electro-optic modulation and digital signal processing (MIMO) at the receiver, the system achieves wavelength channel separation without requiring mechanically or thermally controlled optical components.
2Measurement precision
If precise wavelength control is implemented for transmitter lasers, then wavelength division multiplexing is achieved, but system cost increases due to cooling and temperature-stabilization infrastructure
Solution Approach 1:
The patent employs inexpensive, non-wavelength-stabilized laser diodes instead of costly temperature-controlled wavelength-stabilized lasers. By generating optical frequency combs from these cheap lasers and using MIMO processing for channel separation, the system achieves WDM functionality at a fraction of the cost of traditional wavelength-selective multiplexing systems.
Solution Approach 2:
The patent changes the fundamental operating parameters of the laser system by operating at a single wavelength and generating multiple wavelength channels through optical frequency comb generation. This parameter change eliminates the need for precise wavelength control of individual lasers while maintaining WDM capability through the comb structure and MIMO processing.
3Manufacturing precision
If wavelength-selective multiplexers are used for each wavelength channel, then precise wavelength multiplexing is achieved, but device complexity increases complicating dense deployment
Solution Approach 1:
The patent merges multiple wavelength channel handling functions into a single optical path. Instead of using separate wavelength-selective multiplexers for each channel, the system combines all wavelength channels into a single optical frequency comb output from one laser, and uses MIMO processing at the receiver to separate and handle all channels, dramatically reducing device complexity.
Solution Approach 2:
The patent makes the single-wavelength laser and optical path universal for handling all wavelength channels. The same optical path and modulation scheme are used for all channels in the comb, and the MIMO receiver universally processes all channels through the same signal processing pipeline, eliminating the need for channel-specific optical components.
Data Source
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AI summary
An optical transmitter capable of colorless WDM includes a source of optical frequency comb (OFC) light having a plurality of separate optical frequency tones, and a plurality of optical modulators connected in parallel to modulate different parts of the OFC light with corresponding modulating signals, each of the parts including the plurality of separate optical frequency tones. An optical combiner combines the different parts of the OFC light to obtain an output optical signal of the optical transmitter. MIMO processing may be used to recover the modulating signals at an optical receiver using, or to configure the modulating signals at the transmitter so that each of the frequency tones is modulated with a corresponding target data signal.