Optical Frequency Comb Drift Compensation

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Solution Overview

Problem

Optical frequency combs stabilized to an optical reference cavity experience performance degradation due to slow drifts, such as mechanical and thermal drifts, which existing technologies fail to effectively compensate for.

Innovation Solution

A method and system that utilize a Kalman filter to estimate and adjust for optical reference cavity drift by generating a low-frequency electrical signal, comparing it to a reference signal, and adjusting the laser frequency to compensate for the drift, incorporating an inner and outer control loop to stabilize clock time and oscillation period errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the optical frequency comb is stabilized to an optical reference cavity, then the phase noise is reduced over short time scales, but slow drift occurs due to mechanical and thermal effects

Engineering Contradiction:
Improvephase noiseVSAvoidfrequency stability
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback control system where the optical frequency comb is continuously compared to the optical reference cavity, and the error signal is used to adjust the laser frequency through a feedback loop, thereby compensating for drift while maintaining low phase noise

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the operating parameters of the laser system by introducing a separate drift compensation loop that operates at different time scales than the phase noise stabilization, allowing independent optimization of both short-term precision and long-term stability

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If the laser frequency is adjusted to compensate for drift, then the frequency stability is improved, but the system complexity increases

Engineering Contradiction:
Improvefrequency stabilityVSAvoidcontrol system complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent combines the phase noise stabilization and drift compensation functions into a unified control system that shares common components such as the optical reference cavity and frequency detection mechanisms, reducing overall system complexity while achieving both objectives

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements a nested control structure where the drift compensation loop encompasses the phase noise stabilization loop, with the outer loop operating at slower time scales and the inner loop operating at faster time scales, allowing hierarchical control of different error sources

Inventive Principle:
Principle #7Nested doll (Nesting)

Data Source

PatentEP3652818B1Cavity stabilized laser drift compensation
Publication Date: 2021.04.28 RAYTHEON CO
  • EP3652818B1 patent drawingFigure 1
  • EP3652818B1 patent drawingFigure 2A~2B
  • EP3652818B1 patent drawingFigure 3

AI summary

Generally discussed herein are systems, devices, and methods for providing a frequency stabilized optical frequency comb, including frequency stabilizing the optical frequency comb to a laser that is frequency stabilized to an optical reference cavity, generating a low frequency electrical signal from the optical frequency comb, comparing the generated low frequency electrical signal to a reference low frequency electrical signal, determining an optical reference cavity drift based on the comparison, and then adjusting a frequency of the laser in response to the determined optical reference cavity drift.