Pulsed Laser Repetition Rate Control Using Intensity Cross-Correlation

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Solution Overview

Problem

Existing methods for controlling the pulse repetition rate of pulsed laser oscillators suffer from high phase noise, dependency on intensity noise, and are susceptible to backscattering in optical fibers, requiring complex and expensive setups.

Innovation Solution

A method and apparatus that split the pulsed laser beam into two paths, time-delay one path relative to the other, generate a timing baseband signal using an intensity cross-correlator, and apply a feedback signal to control the pulse repetition rate, reducing phase noise and eliminating the need for external modulators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If interferometric techniques are used to detect timing jitter, then measurement precision is improved, but device complexity increases and requires external modulators

Engineering Contradiction:

Improvetiming jitter detection sensitivityVSAvoidcomplexity of electronics and optical components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the timing information from the optical pulse train by using an intensity cross-correlator that directly measures pulse arrival times, eliminating the need for complex interferometric setups and external modulators while maintaining high measurement precision

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical and optical complexity of interferometric systems with a simpler intensity-based detection scheme using photodetectors and electronic cross-correlation, substituting complex optical modulation mechanisms with direct intensity measurement

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If broad optical bandwidth is used to achieve high noise detection sensitivity, then measurement precision is improved, but loss of energy increases

Engineering Contradiction:

Improvenoise detection sensitivityVSAvoidoptical signal level sacrifice

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent extracts only the necessary timing information from the optical pulses using intensity detection, avoiding the need to process the entire broad optical bandwidth and thereby reducing energy loss while maintaining high noise detection sensitivity through direct pulse timing measurement

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If interferometric techniques are used, then measurement precision is improved, but object-generated harmful factors increase due to backscattering and relative intensity noise

Engineering Contradiction:

Improvephase noise detection capabilityVSAvoidbackscattering noise and intensity noise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the interferometric measurement mechanism with direct intensity cross-correlation of pulse trains, eliminating the sensitivity to backscattering and relative intensity noise that plagues interferometric techniques while maintaining high phase noise detection capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an electronic cross-correlation process as an intermediary between the optical pulse train and the timing measurement, which filters out harmful noise sources like backscattering and intensity noise while preserving the timing information

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Achieves precise control of pulse repetition rate with reduced noise, simplified electronics, and improved signal-to-noise ratio, enabling stable microwaves and ultralow jitter optical pulses.

Implementation Method 1

time-delaying the first pulsed split beam relative to the second pulsed split beam by an optical delay device

Methodology Applied

Scientific EffectOptical path delay:

Implementation Method 2

generating a timing baseband signal based on the time-delayed first pulsed split beam and the second pulsed split beam by a timing detector device

Methodology Applied

Scientific EffectOptical intensity cross-correlation:

Implementation Method 3

a piezoelectric transducer for adjusting a resonator length of a resonator included in the pulsed laser oscillator

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12444899B2Method and apparatus for controlling a pulse repetition rate of a pulsed laser beam, and pulsed laser oscillator with stabilized pulse repetition rate

Publication Date: 2025.10.14 CYCLE GMBH

AI summary

A method is disclosed for controlling a pulse repetition rate of pulsed laser beam 1 created by pulsed laser oscillator 100, includes generating beam 1 by oscillator 100, splitting beam 1 into first pulsed split beam 1a and second pulsed split beam 1b, time-delaying split beam 1a relative to split beam 1b by optical delay device 220, generating timing baseband signal Sc including a timing jitter of the pulse repetition rate based on split beam 1a and second split beam 1b by timing detector device 230, generating feedback signal Sf based on timing baseband signal Sc, and applying feedback signal Sf on oscillator 100 and controlling the pulse repetition rate of beam 1 based on the feedback signal Sf. Furthermore, repetition rate control apparatus 200 for controlling a pulse repetition rate of pulsed laser oscillator 100 and pulsed laser oscillator 100, comprising repetition rate control apparatus 200 are described.