Optical Feedback Tunable Frequency Comb Generation
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Solution Overview
Problem
Conventional methods for generating optical frequency combs suffer from issues such as poor carrier flatness, uncontrollable carrier number, high drive voltage requirements, and strong carrier noise, particularly in achieving tunable frequency combs with stable wavelet space.
Innovation Solution
A repetition frequency-tunable optical frequency comb is generated using a combination of a single-frequency laser resonant cavity, wavelength division multiplexer, optical circulator, and tunable laser-delay module, with optical feedback and frequency-locking mechanisms to produce a comb with tunable frequency space and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional methods (mode-locked laser, non-linear optical fiber, electro-optic modulator) are used to generate optical frequency combs, then a certain number of carriers can be obtained, but the carrier flatness is poor and the carrier number is uncontrollable
Solution Approach 1:
The patent employs optical feedback by redirecting a portion of the output light back to the laser cavity through an optical circulator and feedback mirror. This feedback mechanism enables precise control of the laser modes, achieving both a large number of carriers and excellent carrier flatness. The feedback loop allows real-time adjustment and stabilization of the frequency comb characteristics, resolving the contradiction between carrier quantity and flatness.
2Device complexity
If cascade electro-optic modulators are used to generate optical frequency combs, then the structure is simpler and wavelet space is stable, but high radio frequency drive voltage is needed and carrier flatness is unsatisfactory
Solution Approach 1:
The patent replaces the electro-optic modulation mechanism with an all-optical feedback mechanism. Instead of using high-voltage radio frequency drive signals to control electro-optic modulators, the invention uses optical feedback through an optical circulator and feedback mirror to control the laser cavity modes. This substitution eliminates the need for high drive voltages while maintaining structural simplicity and achieving satisfactory carrier flatness.
3Quantity of substance
If RFS (Recirculating Frequency Shifter) structure is used to generate optical frequency combs, then a relatively large number of carriers with good flatness can be obtained, but strong carrier noise and unapparent carrier phase relationships occur
Solution Approach 1:
The patent uses optical feedback to directly control the laser cavity modes from the source, rather than frequency-shifting an existing comb. This approach generates carriers with inherent phase relationships and suppresses carrier noise by stabilizing the laser operation through feedback. The feedback mechanism ensures clean carrier generation while maintaining a large number of carriers with good flatness, eliminating the noise problems associated with RFS structures.
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 solution provides a simpler method for generating optical frequency combs with stable frequency space and reduced noise, allowing for tunable frequency control and improved carrier flatness, overcoming the limitations of existing technologies.
Implementation Method 1
a single-frequency laser resonant cavity
Implementation Method 2
a portion of the output light is fed back to the laser cavity through an optical circulator and a feedback mirror
Implementation Method 3
The laser cavity is configured to generate a frequency comb spectrum through mode coupling
Data Source
AI summary
The present invention provides a repetition frequency-tunable optical frequency comb generated by basis of optical feedback. The optical frequency comb comprises a single-frequency laser resonant cavity, a wavelength division multiplexer, a single-mode semiconductor pump light source, an optical circulator, a first optical fiber coupler, a second optical fiber coupler, a photoelectric detector, a highly-stable signal source, an error signal processing system, a laser frequency modulation device and a tunable laser-delay module. The present invention performs delay-time processing to the single-frequency laser by the tunable laser-delay module, and achieves an optical feedback by the optical circulator for injecting to the resonant cavity, generating a series of tunable laser longitudinal modes with equal frequency space. Meanwhile, in combination with the highly-stable signal source, the error signal processing system and the laser frequency modulation device, a laser frequency lock is achieved, and the laser frequency comb is generated. The invention obtains a repetition frequency-tunable laser frequency comb with a simple and practical method, having an extensive application prospect and huge application value in fields such as optical fiber sensing and spectroscopy of atom and molecule.