Dual Output Laser Diode for Stable Pump Light Distribution

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Solution Overview

Problem

Doped fiber amplifiers face pump instability due to coherent interactions when pump light is split externally from a single laser diode, leading to increased optical power density and reduced reliability.

Innovation Solution

A dual output laser diode with low reflectivity end facets allows internal splitting of pump light, eliminating the need for external components and reducing optical power density by configuring each end facet to transmit a majority of the pump light, thereby reducing coherent interactions and enhancing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pump light is split externally from a single laser diode, then a single light source is used, but coherent interactions cause pump instability and increased optical power density

Engineering Contradiction:

Improvepump stabilityVSAvoidcoherent interactions

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the single laser diode into two separate laser diodes, each with its own end facet. This segmentation eliminates coherent interactions between the two pump light paths while maintaining a compact dual-output configuration. Each laser diode independently generates pump light for separate doped fiber amplifiers, resolving the pump instability caused by external splitting.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts the problematic external splitting component and replaces it with internal generation of two separate pump light paths. By taking out the external beam splitter and its associated coherent interaction problems, the system achieves stable pumping through two independent laser diodes with low reflectivity end facets.

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If external splitting components are used, then pump light can be distributed, but device complexity increases and reliability decreases

Engineering Contradiction:

Improvepump light distributionVSAvoidexternal splitting components

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of pump light generation and distribution into a single integrated structure. Two laser diodes are positioned with their end facets facing each other, creating an inherent distribution mechanism without external splitting components. This merging eliminates the need for separate beam splitters, mirrors, and alignment mechanisms, reducing device complexity while maintaining pump light distribution capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The dual-output laser diode structure serves multiple functions simultaneously: it generates pump light, distributes it to two separate paths, and provides low reflectivity end facets for efficient coupling into doped fiber amplifiers. This multi-functionality eliminates the need for additional external components, simplifying the overall system architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If high reflectivity end facets are used, then light is confined within the laser diode, but optical power density increases and reliability decreases

Engineering Contradiction:

Improvelaser diode reliabilityVSAvoidoptical power density

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Instead of using high reflectivity end facets to confine light, the patent inverts the approach by using low reflectivity end facets. This allows light to escape more easily from each end facet, reducing the optical power density buildup within the laser diode structure. The low reflectivity facets enable efficient coupling of pump light into the doped fiber amplifiers while maintaining reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

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 stabilizes pump light distribution, reduces maximum optical power density by half, and increases the reliability of the laser diode by allowing equal or unequal pump light power output from each end facet, minimizing the need for external splitting components.

Implementation Method 1

The active section is configured to generate light that propagates toward each of the first and second end facets in response to injection of an electrical drive signal into the active section

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

The first end facet is configured to transmit a majority of the light that reaches the first end facet through the first end facet. The second end facet is configured to transmit a majority of the light that reaches the second end facet through the second end facet

Methodology Applied

Scientific EffectLight transmission through low reflectivity interface: Reflection

Data Source

PatentUS11652332B2Dual output laser diode

Publication Date: 2023.05.16 II VI DELAWARE INC

AI summary

A dual output laser diode may include first and second end facets and an active section. The first and second end facets have low reflectivity. The active section is positioned between the first end facet and the second end facet. The active section is configured to generate light that propagates toward each of the first and second end facets. The first end facet is configured to transmit a majority of the light that reaches the first end facet through the first end facet. The second end facet is configured to transmit a majority of the light that reaches the second end facet through the second end facet.