Common-Wavelength Optical Sources for Lower-Complexity WDM
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Solution Overview
Problem
Conventional WDM systems for RFoF communication are expensive, complex, and difficult to design and maintain due to the use of multiple optical sources with different wavelengths, requiring complex control circuits.
Innovation Solution
A WDM system using multiple optical sources that generate optical beams with a common wavelength, modulated by combined baseband signals and LO signals, optically combined for transmission over an optical fiber, reducing complexity and cost through efficient LO signal generation by cyclically shifting bit patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple optical sources with distinct stable wavelengths are used for WDM, then multi-channel transmission capability is achieved, but system complexity and cost increase
Solution Approach 1:
The patent merges multiple optical sources that would traditionally operate at different wavelengths into a single wavelength source. By using a single laser source operating at a fixed wavelength combined with RF modulation and optical filtering, the system achieves multi-channel WDM transmission without requiring multiple distinct wavelength lasers, thereby reducing system complexity while maintaining multi-channel capability
Solution Approach 2:
The patent introduces RF signals and optical filters as intermediary elements between the single optical source and the multiple channels. The RF modulation serves as an intermediary to encode multiple channels onto the single wavelength, and optical filters act as intermediaries to separate these channels at the receiver, eliminating the need for complex multi-wavelength source control
2Adaptability or versatility
If multiple optical sources with distinct wavelengths are used for WDM, then multi-channel transmission is enabled, but system cost increases
Solution Approach 1:
The patent combines the functions of multiple expensive wavelength-tunable or multi-wavelength laser sources into a single fixed-wavelength laser source. This merging approach significantly reduces component costs, as single-wavelength lasers are simpler and cheaper to manufacture than systems requiring multiple precision wavelength sources with their associated control circuits
Solution Approach 2:
The patent employs cheaper optical components such as standard optical filters and modulators rather than expensive wavelength-stabilized laser systems. These simpler components can be more easily manufactured and replaced, reducing overall system cost while achieving the same multi-channel transmission function
3Adaptability or versatility
If multiple optical sources with distinct wavelengths are used for WDM, then multi-channel transmission is achieved, but system size increases
Solution Approach 1:
The patent merges multiple optical source units into a single compact configuration. By using one laser source shared across multiple channels through RF modulation and optical switching, the physical footprint is dramatically reduced compared to having separate laser sources for each wavelength channel, thereby reducing overall system size while maintaining multi-channel capability
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
Significantly reduces system size, cost, and power consumption while maintaining high throughput by using a common wavelength for optical sources, enabling efficient multi-channel transmission.
Implementation Method 1
The modulators are configured to modulate the optical sources or the optical beams using the combined baseband signals, thereby generating multiple modulated optical signals having different wavelengths
Implementation Method 2
The optical multiplexer is configured to optically combine the modulated optical signals to form a combined optical signal, and to transmit the combined optical signal over an optical fiber
Implementation Method 3
the optical multiplexer is configured to filter the multiple modulated optical signals using multiple respective optical filters having respective passbands
Implementation Method 4
The LO circuit is configured to generate multiple LO signals having different LO frequencies... The LO circuit is configured to generate the LO signals by cyclically shifting predefined respective bit patterns
Data Source
AI summary
A transmitter includes a Local Oscillator (LO) circuit, multiple Radio Frequency (RF) combiners, and an optical transmitter. The LO circuit is configured to generate multiple LO signals having different LO frequencies. The Radio Frequency (RF) combiners are configured to receive multiple baseband signals and to respectively combine the baseband signals with the LO signals to produce combined baseband signals. The optical transmitter includes multiple optical sources, multiple modulators, and an optical multiplexer. The optical sources are configured to generate, when unmodulated, optical beams having a common wavelength. The modulators are configured to modulate the optical sources or the optical beams using the combined baseband signals, thereby generating multiple modulated optical signals having different wavelengths. The optical multiplexer is configured to optically combine the modulated optical signals to form a combined optical signal, and to transmit the combined optical signal over an optical fiber.