Laser Diode Resistance Segmentation for Common-Drive Beam Quality

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Solution Overview

Problem

Conventional trapezoidal and broad stripe laser diodes face issues with hole burning effects, thermal lens formation, and reduced beam quality when operated with common voltage, leading to decreased power and efficiency, especially in high-power applications where separate control of individual sections is complex and costly.

Innovation Solution

The design incorporates a laser diode with a resonator having distinct sections, where the second section features separate resistance elements with higher electrical resistance, allowing for optimal current distribution and reduced current density, thereby minimizing hole burning and thermal lens effects, while maintaining common electrical contacting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If separate control of ridge waveguide region and trapezoidal region is implemented, then beam quality and power output are improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvepower outputVSAvoidcontrol complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The laser diode structure is segmented into a ridge waveguide region and a trapezoidal region with different widths and resistance characteristics. This segmentation allows different current densities to be established in each region through the inherent resistance differences, enabling optimized beam quality and power output without requiring complex external control systems for each segment

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by creating regions with different geometric and electrical properties. The ridge waveguide region has narrower width and lower resistance for high current density operation, while the trapezoidal region has wider width and higher resistance for lower current density operation. This local differentiation optimizes overall performance without requiring active control of each region

Inventive Principle:
Principle #3Local quality

2Device complexity

If common voltage operation is used, then device complexity is reduced, but hole burning effects and thermal lens formation increase

Engineering Contradiction:
Improvecontrol complexityVSAvoidhole burning effects
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces local quality differences through resistance elements with varying specific resistances in different regions of the laser diode. This creates localized current density variations that prevent uniform current distribution, thereby reducing hole burning effects and thermal lens formation while maintaining simple common voltage operation

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the electrical resistance parameter spatially within the device by incorporating resistance elements with different specific resistances. This parameter variation along the laser diode structure modifies the current distribution pattern, preventing the formation of hot spots and thermal lenses that occur with uniform current distribution

Inventive Principle:
Principle #35Parameter changes

3Power

If trapezoidal region is reduced and ridge waveguide region is lengthened, then power and efficiency are improved, but beam quality deteriorates

Engineering Contradiction:
Improvepower outputVSAvoidbeam quality
Core Design Contradiction:
PowerVSShape

Solution Approach 1:

The patent maintains optimal beam quality by preserving the trapezoidal region with its wider geometry, while compensating for potential power losses through the strategic placement of resistance elements. The local quality differences in resistance and geometry work together to optimize both beam quality and power output simultaneously

Inventive Principle:
Principle #3Local quality

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 beam quality and power output by optimizing current distribution, reducing manufacturing costs, and avoiding the need for complex separate control of individual sections, thus improving the overall performance and efficiency of the laser diodes.

Implementation Method 1

the second section has a plurality of separate resistance elements introduced by implantation, the specific electrical resistance of which is greater than the specific electrical resistance of the regions between adjacent resistance elements

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentEP4283802B1Laser diode with improved electrical conduction properties
Publication Date: 2024.12.18 FERDINAND BRAUN INSTITUT GGMBH LEIBNIZ INSTITUT FUR HOCHSTFREQUENZTECHNIK
  • EP4283802B1 patent drawingFigure 1
  • EP4283802B1 patent drawingFigure 2
  • EP4283802B1 patent drawingFigure 3

AI summary

The invention relates to a laser diode with improved electrical conductivity properties and a corresponding diode laser. The object of the present invention is to provide a laser diode with an improved structure that exhibits improved beam quality and performance characteristics when different areas are driven simultaneously.The laser diode (10) has at least one active layer (12) arranged within a resonator (14) and operatively connected to an output coupling element (16), and at least one contact layer (18) for coupling charge carriers into the active layer (12), wherein the resonator (14) has at least one first section (20) and one second section (22), wherein the maximum width (W1) of the active layer (12) in the first section (20) differs from the maximum width (W2) of the active layer (12) in the second section (22), and a projection of the contact layer (18) along a first axis (Z1) extending perpendicular to the active layer (12) overlaps both the first section (20) and the second section (22).According to the invention, it is particularly provided that the second section (22) has a plurality of separate resistance elements (24) introduced by means of implantation, wherein the first section (20) and the second section (22) have a common electrical contact and the ratio between the current component in the first section (20) and the current component in the second section (22) is set via the resistance elements (24).