Surface-Emitting Laser Step Structure Without Oxidation Variability

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Solution Overview

Problem

Conventional surface emitting lasers face challenges in controlling oxidation, leading to variations in current and beam characteristics due to the difficulty in maintaining a consistent structure for current injection and light confinement.

Innovation Solution

A surface emitting laser and array design featuring a substrate with convex parts and a vertical resonator structure, where the first semiconductor layer has a step structure conforming to the convex parts and a current blocking layer with openings, allowing for controlled current injection and optical confinement through refractive index differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If oxidation is used to form current injection and light confinement structure, then current injection and light confinement are achieved, but oxidation control is difficult and variation in current and beam characteristics occurs

Engineering Contradiction:

Improvecurrent characteristics stabilityVSAvoidoxidation control difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the fundamental parameter of the current blocking layer from oxidized AlAs/AlGaAs to non-oxidized AlGaAs with different conductivity type. This parameter change eliminates oxidation control difficulties while maintaining current blocking and optical confinement functions through conductivity type differences and refractive index variations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extracts the oxidation process from the structure formation methodology. By removing the oxidation step entirely and using direct epitaxial growth of AlGaAs layers with different conductivity types, the patent eliminates the source of variation while achieving the same functional outcomes through alternative physical mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

2Manufacturing precision

If oxidation is used to form current injection and light confinement structure, then current injection and light confinement are achieved, but variation in current and beam characteristics occurs

Engineering Contradiction:

Improvestructure consistencyVSAvoidcurrent characteristics variation

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent changes the material parameter from oxidized semiconductor to non-oxidized semiconductor with conductivity type differentiation. This eliminates the variability introduced by oxidation while maintaining structural consistency through controlled epitaxial growth and precise conductivity type assignment in AlGaAs layers.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If conventional oxidation method is used, then current blocking is achieved, but oxidation control is not easy and variation occurs

Engineering Contradiction:

Improvecurrent blocking performanceVSAvoidoxidation process control

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent removes the oxidation process entirely from the manufacturing sequence. Current blocking is achieved through the inherent properties of the AlGaAs material system with different conductivity types, eliminating the need for oxidation control while maintaining effective current blocking performance.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the chemical oxidation process with a physical/structural approach using conductivity type differences and refractive index variations in AlGaAs layers. This replacement eliminates chemical control difficulties while achieving the same functional outcome through material property differentiation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 design effectively narrows current injection and suppresses variations in current and beam characteristics, enhancing the stability and performance of the surface emitting laser and array.

Implementation Method 1

because the step structure part is of the first conductivity type and the current blocking layer is of the second conductivity type different from the first conductivity type, it is possible to perform optical confinement in a lamination in-plane direction owing to a difference in refractive index due to the difference in conductivity type

Methodology Applied

Scientific EffectRefractive index difference: Refraction

Data Source

PatentUS20240022040A1Surface emitting laser and surface emitting laser array

Publication Date: 2024.01.18 SONY GROUP CORP

AI summary

A surface emitting laser according to one embodiment of the present disclosure includes: a substrate having a convex part provided on a surface thereof; and a vertical resonator structure formed on the substrate, and including an active layer, a first semiconductor layer, and a current blocking layer. The first semiconductor layer is a semiconductor layer of a first conductivity type having a step structure part having a shape conforming to the convex part at a location facing the convex part. The current blocking layer is a semiconductor layer of a second conductivity type different from the first conductivity type and having an opening in which an inner peripheral surface is in contact with an outer peripheral surface of the step structure part.