Spatial Division Multiplexing Receiver for Turbulent Optical Links

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Optical communications systems operating through turbulent media face challenges in maintaining effectiveness and efficiency due to wavefront distortions and signal degradation, particularly when increasing telescope diameter to collect more power, which can lead to worse performance compared to single mode receivers.

Innovation Solution

The implementation of photonic integrated circuits with spatial division multiplexing and adaptive digital signal processing techniques, utilizing multimode optical amplifiers, local oscillator lasers, and surface grating couplers to separate and process orthogonal spatial modes, and adjust amplitude, phase, and delay to mitigate turbulence effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If telescope diameter is increased to collect more optical power, then signal collection capability is improved, but turbulence-induced wavefront distortions worsen and performance degrades

Engineering Contradiction:

Improveoptical power collectionVSAvoidsignal quality in turbulent media

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent segments the received optical signal into multiple spatial modes using a mode sorter, which separates different spatial modes of light into distinct channels. This allows independent processing of each mode to mitigate turbulence effects while maintaining the benefits of large aperture collection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from single-mode detection to multi-mode spatial division multiplexing, adding a spatial dimension to signal processing. By detecting multiple orthogonal spatial modes simultaneously and processing them independently through digital signal processing, the system achieves turbulence compensation while maintaining high signal collection efficiency.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If single mode receiver is used to avoid turbulence effects, then signal quality is improved, but optical power collection capability is reduced

Engineering Contradiction:

Improvesignal qualityVSAvoidoptical power collection

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The mode sorter segments the incoming optical signal into multiple spatial modes, allowing the system to use multiple single-mode detectors in parallel. Each detector processes one spatial mode with high quality, while the combination of all modes achieves superior total power collection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges multiple single-mode detection channels through spatial division multiplexing and digital signal processing. By coherently combining the signals from multiple spatial modes, the system achieves both high signal quality (from single-mode detection) and high power collection (from multiple modes).

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If spatial division multiplexing is implemented to process multiple modes, then turbulence mitigation is improved, but device complexity increases

Engineering Contradiction:

Improveturbulence compensation performanceVSAvoidphotonic integrated circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The photonic integrated circuit is designed with multi-functional components that perform multiple operations: mode sorting, signal splitting, photodetection, and electrical signal processing. This universal design achieves turbulence mitigation through spatial division multiplexing while minimizing the number of separate components needed.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces complex mechanical mode separation systems with an integrated photonic circuit that uses waveguide-based mode sorting. This substitution integrates multiple functions into a compact, stable platform that reduces mechanical complexity while maintaining turbulence compensation performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhances signal reception by minimizing the impact of turbulent channels, achieving performance comparable to non-turbulent conditions, even with multiple spatial modes, and improves sensitivity and noise ratio in high-speed optical communications.

Implementation Method 1

direct that received light to a multimode optical amplifier which outputs amplified light

Methodology Applied

Scientific EffectOptical amplification:

Implementation Method 2

surface grating couplers to separate and process orthogonal spatial modes

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 3

photonic integrated circuit(s) where it is received and undergoes spatial division multiplexing and photodetection

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 4

combine the received light with local oscillator laser light

Methodology Applied

Scientific EffectLaser coherence: Laser

Data Source

PatentUS9806839B2Optical compensation using a space division multiplexing electro-optic receiver

Publication Date: 2017.10.31 ACACIA TECH INC

AI summary

Disclosed herein are methods, structures, and devices for optical communications systems operating through turbulent media. More specifically, a spatial division multiplexing photonic integrated circuit is used in conjunction with digital signal processing systems to mitigate the effects of the turbulent media.