Optical Fiber Alignment Using Amplified Spontaneous Emission

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Solution Overview

Problem

Existing systems for injecting a radiation beam into an optical fiber face challenges in alignment due to the small diameter of the fiber relative to the radiation beam, requiring additional light sources for visibility and frequent adjustments to compensate for thermal variations and mechanical disturbances, which increases size, weight, and energy consumption.

Innovation Solution

A system that uses amplified spontaneous emission radiation from a laser amplifier integrated within the optical fiber to both align and amplify the radiation beam, eliminating the need for an external alignment source and reducing system weight, size, and energy consumption by utilizing the same amplifier for both purposes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an external light source is added to illuminate the end of the optical fiber for visibility during alignment, then the fiber end becomes visible in camera images, but the system size, weight, and cost increase

Engineering Contradiction:
Improvealignment visibilityVSAvoidsystem weight
Core Design Contradiction:
Measurement precisionVSWeight of stationary object

Solution Approach 1:

The patent makes the optical fiber serve multiple functions: it acts as both the transmission medium for the radiation beam and as a light source for alignment visualization. The fiber end emits light that illuminates itself, enabling camera-based alignment without requiring separate external illumination devices, thereby reducing system weight and complexity

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

Solution Approach 2:

The optical fiber illuminates itself by emitting light from its end that reflects off the fiber end face and makes it visible to the camera. This self-illumination capability eliminates the need for external light sources, allowing the system to achieve alignment visibility using only the fiber's own optical properties

Inventive Principle:
Principle #25Self-service

2Measurement precision

If an external light source is added to illuminate the end of the optical fiber for visibility during alignment, then the fiber end becomes visible in camera images, but the system complexity and cost increase

Engineering Contradiction:
Improvealignment visibilityVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The optical fiber is designed to perform dual functions: transmitting the radiation beam and providing illumination for alignment visualization. By making the fiber itself the light source, the system eliminates separate illumination components, reducing device complexity while maintaining alignment visibility

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

Solution Approach 2:

The fiber end automatically illuminates itself through emitted light that reflects off its surface, enabling the camera to capture alignment information without requiring external illumination equipment. This self-service approach simplifies the overall system architecture

Inventive Principle:
Principle #25Self-service

3Measurement precision

If the alignment system is designed to compensate for thermal variations and mechanical disturbances, then alignment accuracy is maintained, but the system requires frequent adjustments and becomes more complex

Engineering Contradiction:
Improvealignment accuracyVSAvoidadjustment system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the camera continuously monitors the position of the fiber end, and this information is used to adjust the alignment in real-time. This closed-loop system automatically compensates for thermal variations and mechanical disturbances, maintaining alignment accuracy without requiring complex manual adjustment mechanisms

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The alignment system is designed to be dynamic rather than static, allowing continuous adaptation to changing conditions. The ability to frequently adjust alignment based on real-time feedback enables the system to maintain precision under varying thermal and mechanical conditions without requiring overly complex preventive mechanisms

Inventive Principle:
Principle #15Dynamics

4Use of energy by moving object

If a low-power system is used for alignment on board a satellite, then weight and energy consumption are reduced, but alignment capability may be compromised

Engineering Contradiction:
Improveenergy consumptionVSAvoidalignment capability
Core Design Contradiction:
Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The optical fiber provides its own illumination for alignment by emitting light from its end, eliminating the need for separate power-consuming light sources. This self-illumination capability enables the system to maintain full alignment functionality while operating with minimal or no additional power, making it ideal for satellite applications where energy is constrained

Inventive Principle:
Principle #25Self-service

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 allows for precise alignment and amplification of the radiation beam within the optical fiber, reducing the need for additional components and minimizing energy and resource usage while maintaining alignment accuracy across varying conditions.

Implementation Method 1

an optical detection assembly (2), arranged to detect the position of the end (E) of the optical fiber (1), by receiving a beam of secondary radiation (FS)

Methodology Applied
Scientific EffectOptical detection: Photoelectric Effect

Implementation Method 2

the source of the secondary radiation (FS) being the laser amplifier itself

Methodology Applied
Scientific EffectAmplified spontaneous emission: Laser

Data Source

PatentEP3752874B1Injection of a beam of radiation into an optical fibre
Publication Date: 2024.03.06 AIRBUS DEFENCE & SPACE SAS
  • EP3752874B1 patent drawingFigure 1
  • EP3752874B1 patent drawingFigure 2
  • EP3752874B1 patent drawingFigure 3

AI summary

A system for injecting a beam of useful radiation into an optical fibre (1) comprises a secondary radiation source, which is connected to the optical fibre so that a beam (Fs) of the secondary radiation exits via an end (E) of the optical fibre. It also comprises a variable deviation device (4), for deviating the beam (Fn) of useful radiation toward the end of the optical fibre, an optical detection assembly (2), for identifying a direction of the beam (Fs) of secondary radiation, and an injection controller (5), for controlling the variable deviation device (4) depending on the direction of the beam of the secondary radiation. The secondary radiation may consist of a spontaneous emission amplified by a laser amplifier that is used to amplify the useful radiation. The injecting system may advantageously be used in an optical telecommunication terminal by laser signals.