Transceiver Double Phase Conjugate Mirror Wavefront Correction

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Solution Overview

Problem

Existing optical frequency transmission systems fail to perform wavefront correction when signal light is incident from only one direction, preventing coupling of signal light to an optical fiber and wavefront distortion correction.

Innovation Solution

A transceiver system that includes a guide light source and a photorefractive crystal, where a first double phase conjugate mirror is formed by scattering reference signal light and guide light incident in opposite directions, allowing phase-conjugate light to be coupled to an optical fiber for wavefront correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If signal light is transmitted through space for optical frequency transmission, then the application range is expanded, but wavefront distortion occurs due to atmospheric fluctuations

Engineering Contradiction:

Improveapplication rangeVSAvoidwavefront distortion

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A photorefractive crystal is introduced as an intermediary substance between the transmitted signal light and the atmosphere. The crystal forms a phase conjugate mirror that corrects wavefront distortions by compensating for atmospheric fluctuations, thereby maintaining reliable frequency transmission while preserving the expanded application range of spatial transmission

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a double phase conjugate mirror is formed by photorefractive crystal for wavefront correction, then wavefront distortion is eliminated, but light must be incident from opposite directions which limits system configuration

Engineering Contradiction:

Improvewavefront correctionVSAvoidsystem configuration flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent inverts the traditional approach by having the photorefractive crystal located at the receiving end rather than the transmitting end. The crystal forms a phase conjugate mirror that sends corrected light back through the atmosphere, which then returns to the receiver already corrected. This inversion allows wavefront correction with single-directional incident light, resolving the configuration limitation

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If photorefractive crystal is used for wavefront correction, then atmospheric fluctuation effects are canceled, but the system requires complex double phase conjugate mirror formation

Engineering Contradiction:

Improveatmospheric fluctuation compensationVSAvoidmirror formation complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and utilizes only the essential wavefront correction function of the photorefractive crystal, simplifying the system by eliminating the need for complex double phase conjugate mirror formation. The crystal directly forms a phase conjugate mirror that provides sufficient wavefront correction for single-directional light incidence, reducing overall system complexity while maintaining atmospheric fluctuation compensation

Inventive Principle:

Principle #2Taking out (Extraction)

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 signal light from one direction to be coupled to an optical fiber and performs wavefront correction, ensuring reliable transmission by canceling out wavefront distortions caused by atmospheric fluctuations.

Implementation Method 1

The photorefractive crystal has a medium such as BaTiO3 (barium titanate) that produces a photorefractive effect in which the refractive index changes depending on the intensity of light irradiation

Methodology Applied

Scientific EffectPhotorefractive effect:

Implementation Method 2

when two light waves 1 and 2 are incident on a photorefractive crystal 22a from opposite directions, scattered light 1j and 2j is generated due to the beam fanning effect

Methodology Applied

Scientific EffectBeam fanning effect:

Implementation Method 3

the scattered light 1j and 2j forms a double phase conjugate mirror 22m (also referred to as a mirror 22m) which is a diffraction grating

Methodology Applied

Scientific EffectDiffraction grating: Diffraction Grating

Implementation Method 4

the phase-conjugate light 1c having the wavefront distortion passes through the same atmospheric fluctuation in the reverse direction to that of the light wave 1, the wavefront distortion of the phase-conjugate light 1c due to the atmospheric fluctuation is canceled out

Methodology Applied

Scientific EffectWavefront correction:

Data Source

PatentUS11881900B2Transceiver, spatial light frequency transmission system and spatial light frequency transmission method

Publication Date: 2024.01.23 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

A second transceiver (22) includes a guide light source (22c), a photorefractive crystal (22a), and a frequency control unit (22e). The guide light source (22c) emits guide light (Y3). A double phase conjugate mirror (22m) is formed in a crystal (22a) by scattering of reference signal light (Y1), which has a frequency different from that of the guide light and is incident on the crystal via space (15) after being transmitted from a first transceiver (21) which is a transceiver on the other side, and the guide light that is incident on the crystal in a reverse direction to that of the reference signal light. A frequency control unit (22e) couples the reference signal light emitted from the crystal (22a), which is phase-conjugate light of the guide light generated by the mirror (22m), to an optical fiber (13b).