Optic Signal Receiver Adaptive Optics Feedback Control

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Solution Overview

Problem

Existing optic signal receivers in free-space optical communication systems face inefficiencies due to signal loss and distortion caused by atmospheric turbulence, particularly when using mode splitters like photonic lanterns, which do not effectively utilize the information content of the optical input signal.

Innovation Solution

An optic signal receiver comprising an adaptive optic module, a mode splitting module, and a signal detection module, along with a feedback control unit and estimation unit, which modifies the input signal to optimize its conversion into multi-mode and reduced-mode signals, improving signal detection and control through intensity data measurement and feedback mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mode splitter (photonic lantern) is used to convert multimode optic signals into reduced-mode signals, then atmospheric turbulence effects are mitigated, but signal loss occurs due to mismatch between input optical modes and mode splitter output modes

Engineering Contradiction:
Improvesignal detection accuracyVSAvoidsignal loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements a feedback control system that measures the actual optical modes present in the received signal and dynamically adjusts the mode splitter configuration or selection to match these modes. This feedback mechanism ensures optimal coupling between the received multimode signals and the mode splitter, minimizing signal loss while maintaining the benefits of turbulence mitigation.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically changes operational parameters of the mode splitter based on the detected optical mode distribution. By adjusting parameters such as mode coupling ratios, phase relationships, or selecting different mode splitter configurations, the system optimizes the conversion efficiency from multimode to reduced-mode signals, thereby reducing signal loss while maintaining reliable detection.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If adaptive optics correction is applied to compensate for atmospheric turbulence, then signal focusing is improved, but system complexity increases due to real-time wavefront analysis and deformable mirror control

Engineering Contradiction:
Improvesignal focusing accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system employs self-service mechanisms where the received optical signal itself is used to characterize the atmospheric turbulence and guide the correction process. By analyzing the mode distribution of the incoming signal, the system automatically determines the required adaptive optics compensation without requiring external calibration sources or complex pre-characterization procedures, thereby reducing overall system complexity while maintaining high focusing accuracy.

Inventive Principle:
Principle #25Self-service

3Loss of information

If multiple detection subsections are used to measure different signal components (polarization, wavelength), then information content of detection signal is improved, but device complexity increases

Engineering Contradiction:
Improveinformation contentVSAvoiddetection module complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The detection subsections are designed with multi-functionality, where each subsection can detect multiple signal properties (polarization, wavelength, mode) through configurable optical paths and detection algorithms. This universal design allows a single detection subsection to perform multiple measurement functions, thereby capturing comprehensive signal information while avoiding the need for separate dedicated detectors for each parameter, thus controlling device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 configuration enhances the information content and efficiency of signal detection by minimizing signal loss and distortion, optimizing the conversion of multi-mode signals into reduced-mode signals, thereby improving the signal-to-noise ratio and overall communication efficiency.

Implementation Method 1

The adaptive optic module (111) is to modify a received optic input signal (L) under control of a detection control signal (S) into a multi-mode optic output signal (L')

Methodology Applied
Scientific EffectAdaptive optics wavefront correction:

Implementation Method 2

Atmospheric turbulence influences the state of the optical beam used as the signal carrier

Methodology Applied
Scientific EffectAtmospheric turbulence: Turbulence

Implementation Method 3

The mode splitting module (112) is configured to branch the multi-mode optic output signal (L') off into multiple reduced mode optic signals (L1, L2, ..., Ln)

Methodology Applied
Scientific EffectOptical mode splitting:

Implementation Method 4

The signal detection module (113) is configured to issue a detection signal (I) that comprises a plurality of signal detection sections (113_1, 113_2, ..., 113_n), each of which is configured to measure intensity data of a respective one of the reduced mode optic signals

Methodology Applied
Scientific EffectOptical intensity detection:

Data Source

PatentEP4115541B1Optic signal receiver, optic communication system and optic communication method
Publication Date: 2024.05.15 NEDERLANDSE ORG VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK TNO
  • EP4115541B1 patent drawingFigure 1~2
  • EP4115541B1 patent drawingFigure 3~4
  • EP4115541B1 patent drawingFigure 5~5A

AI summary

An optic signal receiver (1) is provided that comprises an optic signal detection unit (11) an estimation unit (12), and a feedback control unit (13) to provide a detector control signal (S).The optic signal detection unit (11) comprises an adaptive optic module (111), a mode splitting module (112) and a signal detection module (113), wherein the adaptive optic module (111) is to modify a received optic input signal (L) under control of the detector control signal (S) into a multi- mode optic output signal (Ĺ), the mode splitting module (112) is configured to branch the multi-mode optic output signal (Ĺ) off into multiple reduced mode optic signals (L 1 , L 2 ,..., L n ) and the signal detection module (113) is configured to issue a detection signal (I), the signal detection module (113) comprising a plurality of signal detection sections that are each configured to measure an intensity of a respective one of the reduced mode optic signals and to provide a respective indicator (I 1 ,I 2 ,..., I n ) indicative of the measured intensity as a component of the detection signal (I). The feedback control unit (13) is configured to minimize a difference between the detection signal (I) and a detection reference signal (I d ) with the detector control signal (S). The estimation unit (12) is configured to issue a further input signal (CIS) to the feedback control unit (13) based on a model of the optic signal detection unit (11).