Optical Comb Frequency Control Beyond Half Repetition Limits
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Solution Overview
Problem
Conventional optical comb light sources are limited in the range of optical frequency change due to the restriction that the beat frequency must be lower than half the repetition frequency, restricting the flexibility in adjusting the optical frequency of one mode of the optical comb.
Innovation Solution
An optical comb light source with an optical frequency changing section, such as an acousto-optic modulator, is used to change the optical frequency of a reference wavelength light, allowing the mode optical frequency to be controlled such that the difference with a target optical frequency has a predetermined value, enabling changes exceeding half the repetition frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the beat frequency is set to a predetermined value to stabilize the optical comb frequency, then the optical frequency can be controlled with high accuracy, but the range of optical frequency change is limited to less than half the repetition frequency
Solution Approach 1:
The optical frequency adjustment is divided into two independent segments: (1) coarse adjustment using the repetition frequency of the optical comb, and (2) fine adjustment using the beat frequency. This segmentation allows the system to achieve both wide adjustment range and high precision by combining the advantages of both methods without being constrained by the limitation of using beat frequency alone.
Solution Approach 2:
The invention adds a new dimension to frequency adjustment by utilizing the repetition frequency degree of freedom in addition to the beat frequency degree of freedom. This transforms the single-dimensional frequency control problem into a two-dimensional control problem, enabling the optical frequency to be adjusted over a wider range while maintaining precision through the combined control of both parameters.
2Adaptability or versatility
If the beat frequency is increased to expand the optical frequency change range, then the adjustment range increases, but the frequency stability deteriorates due to the constraint that fbeat must be lower than frep/2
Solution Approach 1:
The frequency adjustment is segmented into coarse adjustment (using repetition frequency) and fine adjustment (using beat frequency). This allows the system to achieve wide adjustment range through the coarse adjustment component while maintaining frequency stability through the precise fine adjustment component, eliminating the need to compromise stability for range expansion.
Solution Approach 2:
The invention changes the control parameters from solely beat frequency to a combination of repetition frequency and beat frequency. By adjusting the repetition frequency parameter independently, the system can expand the overall adjustment range without being constrained by the beat frequency limitation, while maintaining stability through proper control of both parameters.
3Ease of operation
If only the beat frequency is used to change the optical frequency, then the control method is simple, but the frequency change range is limited to less than half the repetition frequency
Solution Approach 1:
The control system is segmented into two independent control paths: one for repetition frequency and one for beat frequency. This segmentation maintains operational simplicity by providing clear, separate control mechanisms while expanding the adjustment range through the combination of both control paths, allowing intuitive operation without sacrificing versatility.
Solution Approach 2:
The invention makes the control system multi-functional by enabling it to perform both coarse frequency adjustment (via repetition frequency control) and fine frequency adjustment (via beat frequency control). This multi-functionality expands the overall adjustment range while maintaining ease of operation through the systematic division of control responsibilities.
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
The optical frequency of one mode can be changed by more than half the repetition frequency, enhancing the flexibility and range of optical frequency adjustment in the optical comb.
Implementation Method 1
an optical frequency changing section, such as an acousto-optic modulator, is used to change the optical frequency of a reference wavelength light
Data Source
AI summary
An optical comb light source outputs an optical comb having a plurality of modes. The optical comb light source includes an optical comb generating section, an optical frequency changing section, and a mode optical frequency controlling section. The optical comb generating section generates the optical comb. The optical frequency changing section receives a reference wavelength light having a predetermined optical frequency and changes the optical frequency of the reference wavelength light for output. The mode optical frequency controlling section controls a mode optical frequency that is an optical frequency of one mode of the plurality of modes such that a difference between the mode optical frequency and a target optical frequency that is an optical frequency of an output from the optical frequency changing section has a predetermined value. The optical comb generating section changes optical frequencies of the plurality of modes according to the controlled mode optical frequency.