Spatial Optical Transmitter Polarization Diversity

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Solution Overview

Problem

In spatial optical communication, the increase in system scale due to the need for multiple tracking sensors and mirrors to compensate for directional deviations in optical receivers limits the stability and efficiency of communication, especially when multiple optical systems are involved.

Innovation Solution

The solution involves modulating an optical signal into two orthogonal polarizations, which are then transmitted, allowing for stable communication without the need for complex direction control, thereby reducing system scale and maintaining diversity effects similar to having multiple optical systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple optical systems are used in the optical receiver to compensate for wavefront distortion, then communication stability is improved, but system scale increases

Engineering Contradiction:
Improvecommunication stabilityVSAvoidsystem scale
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Instead of using multiple optical systems at the receiver side to achieve diversity, the patent inverts the approach by transmitting multiple optical signals with different polarizations from a single optical system at the transmitter side. This allows the receiver to achieve diversity effect with a single optical system, resolving the contradiction between communication stability and system scale.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces polarization dimension to the optical signal transmission. By modulating optical signals with different polarizations (e.g., horizontal and vertical, or left and right circular polarization), the system achieves diversity in the polarization domain rather than requiring multiple spatial optical systems, thus maintaining stability while reducing system complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If tracking sensors and tracking mirrors are provided for each optical system to compensate directional deviation, then directional accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvedirectional accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes a single tracking sensor and tracking mirror serve multiple functions by using them to track and control a single optical system that transmits multiple polarization-diverse signals. This universal approach eliminates the need for separate tracking systems for each optical path, reducing device complexity while maintaining directional accuracy through the polarization diversity already embedded in the transmitted signals.

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

3Reliability

If multiple optical systems are used to achieve diversity effect, then communication reliability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent inverts the conventional approach by achieving diversity at the transmitter side through polarization modulation rather than using multiple receiver optical systems. This reduces the number of optical components that need to be manufactured and assembled, thereby lowering manufacturing costs while maintaining communication reliability through the polarization diversity effect.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the polarization parameter of the optical signal to create diverse transmission paths. By modulating the polarization state of light from a single optical system, the patent achieves diversity effect without needing to manufacture and deploy multiple identical optical systems, thus reducing manufacturing complexity and cost.

Inventive Principle:
Principle #35Parameter changes

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 enables stable spatial optical communication with reduced system complexity and increased efficiency by utilizing orthogonal polarizations to maintain signal integrity and diversity without the need for extensive direction control or multiple optical systems.

Implementation Method 1

polarizations of the two divided optical signals are rotated, and the two divided optical signals are transmitted to space as optical signals of two orthogonal polarizations

Methodology Applied
Scientific EffectPolarization rotation: Polarisation

Data Source

PatentEP3926857B1Spatial optical transmitter and spatial optical communication system
Publication Date: 2023.11.15 MITSUBISHI ELECTRIC CORP
  • EP3926857B1 patent drawingFigure 1~2
  • EP3926857B1 patent drawingFigure 3~4
  • EP3926857B1 patent drawingFigure 5~7

AI summary

A spatial optical transmitter (1) modulates an optical signal of a single wavelength in accordance with a signal to be transmitted, divides the modulated optical signal into two, rotates polarizations of the two divided optical signals, and transmits the two optical signals as optical signals of two orthogonal polarizations to space.