Atomic Clock Laser Locking with Backup Absorption Lines
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Solution Overview
Problem
Optical atomic clocks face challenges in locking a spectroscopy laser to a specific absorption line due to fabrication variations, aging, mode hops, and environmental conditions, leading to reduced yield and device lifetimes.
Innovation Solution
A method and system that utilize a peak detection algorithm to identify a preferred absorption line and backup absorption lines, employing machine learning and frequency comb techniques to adjust the spectroscopy laser's lasing mode, ensuring stable lock even when the preferred line is unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single absorption line is used for laser locking, then frequency stability is improved, but reliability deteriorates due to fabrication variations, aging, and mode hops
Solution Approach 1:
The system changes the parameter of absorption line selection dynamically. Instead of being fixed on a single absorption line, the system can switch between multiple absorption lines based on whether the laser can successfully lock to the preferred line, accommodating variations in laser gain profile due to fabrication, aging, or mode hops
Solution Approach 2:
The system performs preliminary identification of the laser's location on the absorption spectrum before attempting to lock to the preferred absorption line. This preliminary action allows the system to detect potential locking issues early and switch to backup lines proactively rather than reactively
2Measurement precision
If laser wavelength is fixed for a specific absorption line, then locking precision is improved, but adaptability deteriorates due to gain profile shifts and mode hops
Solution Approach 1:
The system transitions from a static wavelength configuration to a dynamic one. The laser wavelength is no longer fixed but can be adjusted to match different absorption lines based on real-time detection of the laser's actual operating characteristics and its location on the absorption spectrum
Solution Approach 2:
The laser system gains multi-functionality by being capable of locking to multiple different absorption lines. This universal capability allows the same laser to adapt to different operating conditions, fabrication variations, and aging effects by switching between available absorption lines
3Measurement precision
If temperature is adjusted to reach target absorption line, then locking accuracy is improved, but system complexity increases due to temperature control requirements
Solution Approach 1:
The system changes the approach from adjusting temperature to achieve locking to adjusting the absorption line selection based on the laser's actual characteristics. This parameter change eliminates the need for complex temperature control while maintaining locking accuracy through software-based adaptation
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
Ensures accurate frequency stabilization of the frequency comb, extending the operational lifetime of optical atomic clocks by adapting to gain profile shifts and environmental constraints.
Implementation Method 1
identifying a location of a spectroscopy laser on an absorption spectrum of the atomic reference
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
Embodiments herein describe peak detection techniques for selecting an absorption line to lock a spectroscopy laser in a frequency reference (e.g., an atomic clock). In one embodiment, an atomic reference is used which has many absorption lines within a relatively small frequency range (e.g., within a gain profile of the spectroscopy laser). The peak detection techniques can evaluate which of these lines a laser can be locked to. For example, the peak detection algorithm can define a preferred absorption line. But if for some reason the spectroscopy laser cannot be locked to the preferred absorption line, the peak detection technique has at least one backup absorption line. By having a set of candidate absorption lines, the peak detection algorithm can identify a suitable absorption line for lasers with different gain regions, or as gain regions change.