Edge-Emitting Semiconductor Laser Chip Current Confinement

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Solution Overview

Problem

Edge-emitting semiconductor laser chips face challenges in achieving good beam quality, particularly at high optical output powers, due to excessive current widening and phase front warping, leading to increased beam divergence and reduced spatial coherence.

Innovation Solution

The implementation of delimiting structures on both sides of the contact strip, which are arranged to confine current expansion and create a high charge carrier density profile, favoring lower lateral modes by reducing current flow in edge regions and scattering higher modes, thereby enhancing the amplification of the fundamental mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the semiconductor laser chip operates at high optical output powers, then the output power increases, but the beam quality deteriorates due to excessive current widening and phase front warping

Engineering Contradiction:
Improveoptical output powerVSAvoidbeam quality
Core Design Contradiction:
PowerVSShape

Solution Approach 1:

The patent segments the contact strip into multiple discrete contact regions separated by delimiting structures. This segmentation prevents excessive current widening by confining current flow to specific regions, thereby maintaining beam quality even at high optical output powers while still achieving high total power output through multiple emitters.

Inventive Principle:
Principle #1Segmentation

2Shape

If delimiting structures are added to confine current expansion, then beam quality improves, but device complexity increases

Engineering Contradiction:
Improvebeam qualityVSAvoidstructure complexity
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The delimiting structures are strategically placed only at specific locations where current confinement is needed, rather than uniformly across the entire device. This local application of delimiting structures improves beam quality by confining current expansion in critical areas while minimizing the overall structural complexity and maintaining ease of fabrication.

Inventive Principle:
Principle #3Local quality

3Stability of the object's composition

If the contact strip width is increased to improve current distribution, then current distribution improves, but beam divergence increases

Engineering Contradiction:
Improvecurrent distributionVSAvoidbeam divergence
Core Design Contradiction:
Stability of the object's compositionVSShape

Solution Approach 1:

Instead of using a single wide contact strip that causes beam divergence, the patent segments it into multiple narrower contact regions separated by delimiting structures. This segmentation maintains good current distribution within each region while preventing excessive lateral current expansion, thereby reducing beam divergence even as total output power increases.

Inventive Principle:
Principle #1Segmentation

4Power

If multiple emitters are used to increase output power, then optical output power increases, but spatial coherence decreases

Engineering Contradiction:
Improveoptical output powerVSAvoidspatial coherence
Core Design Contradiction:
PowerVSStability of the object's composition

Solution Approach 1:

The patent combines multiple emitters into a single integrated laser chip structure with shared delimiting structures and coordinated current confinement. This merging approach allows multiple emitters to operate simultaneously at high power while maintaining spatial coherence through unified current management and phase front control, preventing the coherence degradation that would occur with independent emitter operation.

Inventive Principle:
Principle #5Merging (Combining)

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 effectively reduces horizontal beam divergence and maintains efficiency even at high optical output powers, ensuring improved beam quality and coherence by suppressing higher lateral modes and enhancing the amplification of lower modes.

Implementation Method 1

at least two delimiting structures for delimiting the spread of current between the contact strip and the active zone, the delimiting structures being arranged on both sides of the contact strip

Methodology Applied
Scientific EffectCurrent confinement:

Implementation Method 2

During operation of the semiconductor laser chip, electromagnetic radiation is generated and amplified in the active zone

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 3

scattering higher modes, thereby enhancing the amplification of the fundamental mode

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP2347482B1Edge-emitting semiconductor laser chip
Publication Date: 2017.01.25 OSRAM OPTO SEMICON GMBH & CO OHG
  • EP2347482B1 patent drawingFigure 1
  • EP2347482B1 patent drawingFigure 2~3
  • EP2347482B1 patent drawingFigure 4~5

AI summary

The invention relates to an edge-emitting semiconductor laser chip (1), comprising – a semiconductor body (100), which comprises at least one active zone (14) in which electromagnetic radiation (10) is generated during operation of the semiconductor laser chip (1), - at least one contact strip (2), which is arranged on a cover surface (1a) on a top of the semiconductor body (100), and – at least two delimiting structures (4) for delimiting the current spreading between the contact strip (2) and the active zone (14), wherein – the delimiting structures (4) are arranged on both sides of the contact strip (2).