Optical Frequency Comb Stitching With Overlap Phase Alignment
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Solution Overview
Problem
Generating a frequency comb with a large number of tones, each with adequate and similar optical power, over a wide band of frequencies, while ensuring tunability in wavelength, bandwidth, and tone spacing, is challenging.
Innovation Solution
An optical frequency comb generation apparatus that combines light from multiple continuous wave laser sources, uses a spectral filter to select overlapping tones, and applies feedback control to align frequencies and phases, employing cascaded optical modulators and an adjustment apparatus to tune the electrical signal for coherent comb generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single frequency comb source is used, then device complexity is reduced, but spectral efficiency and capacity are limited
Solution Approach 1:
The patent combines multiple frequency combs generated from different laser sources into a single integrated comb structure. The comb generator receives light from multiple continuous wave laser sources and produces a combined output that integrates multiple frequency combs, thereby increasing spectral efficiency without requiring separate comb sources for each laser.
Solution Approach 2:
The comb generator is designed to handle multiple laser sources simultaneously and produce a unified frequency comb output that serves all comb-based applications. This multi-functional device replaces what would otherwise require multiple separate comb generators, reducing overall system complexity while maintaining high spectral efficiency.
2Adaptability or versatility
If multiple laser sources are combined, then bandwidth and tone spacing tunability are improved, but frequency and phase alignment becomes more difficult
Solution Approach 1:
The patent employs feedback control apparatus that receives the filtered output and produces control signals to adjust the light entering the comb generator. This feedback mechanism continuously monitors and corrects frequency and phase deviations, ensuring substantial alignment of comb tones from different laser sources while maintaining tunability of bandwidth and tone spacing.
Solution Approach 2:
The system dynamically adjusts the optical paths and phase of each laser source through feedback control. The adjustment apparatus modifies the light from each laser source in real-time to compensate for frequency and phase variations, enabling flexible tuning while maintaining precise alignment of the combined frequency comb.
3Productivity
If a wide frequency band is covered, then spectral efficiency increases, but maintaining adequate and similar optical power across all tones becomes more challenging
Solution Approach 1:
The patent applies different characteristics to different parts of the frequency comb spectrum. The comb generator and feedback control system independently adjust the optical power of individual comb lines or frequency regions, allowing each part of the spectrum to have optimized power characteristics while maintaining overall spectral efficiency across the wide frequency band.
4Productivity
If feedback control is applied to align frequencies and phases, then coherence and spectral efficiency are improved, but device complexity increases
Solution Approach 1:
The feedback control apparatus receives the filtered output from the spectral filter and produces control signals that adjust the light entering the comb generator. This feedback loop aligns the frequencies and phases of comb tones from different laser sources, improving coherence and spectral efficiency. The feedback mechanism integrates seamlessly with the comb generator architecture, adding control functionality without significantly increasing overall device complexity.
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
Achieves a wideband, coherent optical frequency comb with aligned frequencies and phases, providing high spectral efficiency and tunability, thus enabling cost and energy savings in optical communications.
Implementation Method 1
a spectral filter arranged to receive a portion of the combined output and to selectively produce a filtered output comprising at least one pair of tones from the region of overlap
Implementation Method 2
a series of cascaded optical modulators comprising at least one phase modulator and at least one intensity modulator or intensity-modulated laser source
Data Source
AI summary
An optical comb generator receives light from at least two continuous wave laser sources, produces a different frequency comb from each laser source, and produces an output that it the simultaneous combination of the different frequency combs. The different frequency combs span different frequency bands, but at least partially overlap in frequency with an adjacent comb in a region of overlap. A spectral filter produces a filtered output that has at least one pair of tones from the region of overlap, the pair of tones comprising one tone from each of two adjacent combs. Feedback control based on the filtered output is applied to adjust the light entering the comb generator such that the frequencies and phases of the pair of tones from the region of overlap are aligned. In this way, the multiple different overlapping combs are stitched together to form a single seamless comb spanning a broader frequency range.