Optical Clock Synchronization Using Interference-Based Time Offset Measurement

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Solution Overview

Problem

Current clock synchronization methods, particularly for advanced clocks like optical clocks, face challenges in achieving sub-picosecond precision and distributing synchronized timing signals across remote devices and systems, leading to limitations in navigation accuracy and data correlation in applications such as satellite communication and electrical grids.

Innovation Solution

A system and method that utilize a receiver and processor to align and measure interference patterns between local and remote femtosecond laser pulse sequences, calculating a time offset with temporal resolution as a fraction of the pulse widths to synchronize clocks, including a reference oscillator and femtosecond laser for generating stabilized pulse sequences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional clock synchronization methods are used, then device complexity is reduced, but measurement precision deteriorates (cannot achieve sub-picosecond accuracy)

Engineering Contradiction:

Improvetime offset measurement precisionVSAvoidsynchronization system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces traditional electronic/electromagnetic signal-based synchronization methods with an optical interference-based system. Optical pulses are used instead of electrical signals, and interferometric measurement is employed instead of conventional electronic timing analysis, enabling sub-picosecond precision while managing system complexity through optical domain operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes the interference pattern formation as a phase transition phenomenon in the optical domain. By creating and analyzing interference patterns between local and remote optical pulses, the system achieves precise time offset measurement through the phase relationships in the interference pattern, enabling sub-picosecond resolution.

Inventive Principle:

Principle #36Phase transitions

2Measurement precision

If optical clocks with high stability are used, then measurement precision is improved, but the difficulty of detecting and measuring time offsets increases

Engineering Contradiction:

Improveclock stabilityVSAvoidtime offset measurement difficulty

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces an interferometer as an intermediary device that converts the difficult-to-measure time offset between optical clocks into an observable interference pattern. The interferometer acts as a mediator that transforms the temporal information into spatial intensity variations that can be easily detected and analyzed, significantly reducing measurement difficulty while maintaining high clock stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If sub-picosecond synchronization accuracy is achieved, then navigation accuracy and data correlation are improved, but loss of time in synchronization processes increases

Engineering Contradiction:

Improvesynchronization accuracyVSAvoidsynchronization processing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent employs continuous optical pulse transmission and continuous interferometric measurement, eliminating the need for discrete synchronization steps. The system continuously monitors and adjusts time offsets through ongoing optical interference measurements, achieving sub-picosecond accuracy without the time losses associated with periodic synchronization protocols and discrete adjustment cycles.

Inventive Principle:

Principle #20Continuity of useful action

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 precise synchronization of clocks with sub-picosecond accuracy, enhancing the distribution of precise timing signals and improving navigation and data transfer reliability across remote systems.

Implementation Method 1

an interferometer configured to create an interference pattern between the spatially aligned local pulse sequence and remote pulse sequence

Methodology Applied

Scientific EffectInterference: Interference

Implementation Method 2

optical elements configured to spatially align the local pulse sequence and the remote pulse sequence

Methodology Applied

Scientific EffectLight: Light

Data Source

PatentUS8836405B2System and method for synchronizing a local clock with a remote clock

Publication Date: 2014.09.16 RAYTHEON CO

AI summary

A system for synchronizing a first clock and a second clock includes a receiver associated with the first clock, configured to receive a remote pulse from the second clock. The remote pulse has a pulse repetition frequency and spectral characteristics that are known to the local clock. The system also includes a local pulse emitter configured to create a local pulse at the first clock, and optics configured to align the local pulse and the remote pulse. The system further includes an interferometer configured to create an interference pattern between the local pulse and the remote pulse. A controller is provided that is configured to calculate a time delay between the first clock and the second clock based on the interference pattern between the local pulse and the remote pulse.