Optical Frequency Control via Beat Detection and Frequency Division

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Solution Overview

Problem

Existing optical frequency control devices require a frequency synthesizer to change the frequency difference between controlled output light and reference light over a wide band, leading to increased circuit complexity and device size due to the need for filters to suppress unnecessary frequencies.

Innovation Solution

An optical frequency control device that modulates first light with a local oscillation signal, detects a differential beat signal, and frequency-divides it to adjust the second light's frequency using a phase error signal, eliminating the need for a frequency synthesizer by setting appropriate frequency division numbers based on the desired frequency difference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a frequency synthesizer is used to change the frequency difference between controlled output light and reference light over a wide band, then the frequency control range is improved, but the device complexity and size increase due to the need for filters to suppress unnecessary frequencies

Engineering Contradiction:

Improvefrequency control rangeVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the frequency synthesizer and its associated filters from the optical frequency control device. By using a different technical approach that does not require frequency synthesis, the patent removes the source of circuit complexity and device size increase while maintaining wide band frequency control capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the traditional frequency synthesizer mechanism with an alternative approach using optical mixing and frequency division. This substitution eliminates the need for complex filter circuits while achieving the same frequency control function, thereby reducing device complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a frequency synthesizer with filters is used to suppress unnecessary frequencies, then the frequency control accuracy is improved, but the device size becomes larger

Engineering Contradiction:

Improvefrequency control accuracyVSAvoiddevice size

Core Design Contradiction:

Measurement precisionVSVolume of stationary object

Solution Approach 1:

The invention extracts and removes the filter components from the device architecture. By achieving frequency control through alternative means (optical mixing and frequency division), the patent eliminates the space-consuming filters while maintaining frequency control accuracy

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses optical copying/mixing approaches where optical signals are mixed and frequency-divided to achieve the desired frequency control. This optical-domain approach replaces the need for electrical filters, reducing device size while maintaining precision

Inventive Principle:

Principle #26Copying

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

Enables changing the frequency difference between the first and second light frequencies without a frequency synthesizer, reducing device complexity and size while maintaining precise frequency control.

Implementation Method 1

modulate the first light with a local oscillation signal oscillated by a first local oscillation signal source, and detect a differential beat signal including a differential frequency between a frequency of sideband light included in the first light, which is modulated

Methodology Applied

Scientific EffectOptical modulation: Phase Modulation

Implementation Method 2

detect a differential beat signal including a differential frequency between a frequency of sideband light included in the first light, which is modulated, and the second frequency

Methodology Applied

Scientific EffectBeat signal detection: Beat (acoustics)

Implementation Method 3

frequency-dividing a differential beat signal detected by the detection circuit with a first frequency division number, by frequency-dividing a reference signal oscillated by a reference signal source with a second frequency division number

Methodology Applied

Scientific EffectFrequency division:

Data Source

PatentUS11835844B2Optical frequency control device, optical oscillation device, frequency conversion device, and radio wave generation device

Publication Date: 2023.12.05 MITSUBISHI ELECTRIC CORP

AI summary

An optical frequency control device includes: a detection circuit to receive first light including a first frequency, receive second light including a second frequency, modulate the first light with a local oscillation signal, and detect a differential beat signal between the frequency of sideband light included in the modulated first light and the second frequency; a light source control circuit to change the second frequency by frequency-dividing the differential beat signal with a first frequency division number, by frequency-dividing a reference signal with a second frequency division number, and by outputting a phase error signal indicating a phase difference between the frequency-divided differential beat signal and the frequency-divided reference signal; and a signal processing unit to set each of the first frequency division number and the second frequency division number according to the set value of a frequency difference between the first frequency and the second frequency.