Tunable Laser Ring-Phase Feedback for Low Linewidth
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Solution Overview
Problem
Existing tunable lasers face challenges in achieving low linewidth without increasing device size, as longer cavities are required to limit linewidth, which can lead to cavity mode hop and instability.
Innovation Solution
The use of intra-cavity ring filters with thermos-optic phase shifters (TOPS) and a feedback loop that detunes the laser by adjusting the ring phase, allowing for low linewidth operation without the need for long cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If longer cavities are used to limit linewidth, then phase noise is reduced, but device size increases and cavity mode hop occurs
Solution Approach 1:
The patent changes the operating parameters of the laser system by introducing active feedback control that dynamically adjusts cavity length and laser current. This allows the system to achieve low linewidth operation without requiring physically long cavities, as the feedback loop compensates for phase noise through real-time parameter adjustment rather than relying solely on increased cavity length.
Solution Approach 2:
The patent implements a feedback control system that monitors laser output and actively adjusts cavity parameters to minimize phase noise. This feedback mechanism enables the system to achieve linewidth stability equivalent to or better than long passive cavities, while maintaining a compact physical size by dynamically correcting deviations rather than relying on inherent physical length for stability.
2Reliability
If longer cavities are used to limit linewidth, then phase noise is reduced, but device complexity increases
Solution Approach 1:
The patent replaces complex passive long-cavity structures with a simpler active feedback control system. The feedback loop uses standard components (photodetectors, modulators, control electronics) to achieve linewidth stabilization, avoiding the need for physically complex long cavity designs while maintaining or improving performance.
Solution Approach 2:
The patent substitutes mechanical/physical cavity length extension with electronic feedback control. Instead of relying on the mechanical property of long cavity length to reduce phase noise, the system uses electronic signals to actively compensate and control linewidth, replacing a passive mechanical solution with an active electronic control system.
3Reliability
If intra-cavity ring filters with TOPS are used, then phase noise is reduced and linewidth is narrowed, but device complexity increases
Solution Approach 1:
The patent integrates multiple functions into the feedback control system, which simultaneously performs wavelength stabilization, linewidth control, and mode selection. The same feedback loop that stabilizes the laser also works with the intra-cavity ring filters to achieve phase noise reduction, eliminating the need for separate control systems and reducing overall device complexity despite the advanced functionality.
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
This approach enables the stabilization of the laser against reflection feedback, reduces phase noise, and allows for compact tunable laser designs with high optical power and low electrical power consumption.
Implementation Method 1
intra-cavity ring filters with thermos-optic phase shifters (TOPS) and a feedback loop that detunes the laser by adjusting the ring phase
Implementation Method 2
a feedback loop that detunes the laser by adjusting the ring phase, allowing for low linewidth operation
Implementation Method 3
Tunable laser output has phase noise. In many embodiments, the amount of phase noise in a specified frequency range may be represented by linewidth.
Data Source
AI summary
A method, apparatus, and system for adjusting the phase noise of a laser.