VCSEL Array Layout With Isolated Cathodes and Common Anode

Solution Overview

Problem

Existing VCSEL arrays face challenges in achieving high-density emitter configurations with efficient electrical connections, particularly when using p-type substrates, which result in higher defect density, optical loss, and increased fabrication complexity, limiting their performance and manufacturability.

Innovation Solution

A VCSEL array design featuring an n-type substrate as a common anode and isolated cathodes for each emitter group, incorporating a tunnel junction within the bottom mirror structure to reverse carrier type, allowing for independent electrical connections and reducing voltage drop, thus improving electrical and optical efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If p-type substrates are used in VCSEL arrays, then conventional fabrication can be maintained, but defect density increases and optical loss increases

Engineering Contradiction:

Improveconventional fabricationVSAvoiddefect density

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent inverts the conventional VCSEL structure by using an n-type substrate instead of a p-type substrate. This inversion allows the n-type substrate to serve as the common anode, fundamentally changing the doping type and carrier polarity in the bottom mirror structure and active region, thereby reducing defect density and optical loss while maintaining fabrication feasibility

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If p-type substrates are used in VCSEL arrays, then conventional fabrication can be maintained, but optical loss increases

Engineering Contradiction:

Improveconventional fabricationVSAvoidoptical loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent inverts the conventional VCSEL structure by using an n-type substrate instead of a p-type substrate. This inversion allows the n-type substrate to serve as the common anode, fundamentally changing the doping type and carrier polarity in the bottom mirror structure and active region, thereby reducing defect density and optical loss while maintaining fabrication feasibility

Inventive Principle:

Principle #13The other way round (Inversion)

3Device complexity

If common anode configuration is implemented, then fabrication complexity is reduced, but voltage drop increases

Engineering Contradiction:

Improvefabrication complexityVSAvoidvoltage drop

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent inverts the conventional VCSEL structure by using an n-type substrate instead of a p-type substrate. This inversion allows the n-type substrate to serve as the common anode, fundamentally changing the doping type and carrier polarity in the bottom mirror structure and active region, thereby reducing defect density and optical loss while maintaining fabrication feasibility

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the electrical parameters by introducing a tunnel junction with specific resistance characteristics (e.g., 0.1-10 ohms) to compensate for the voltage drop in the common anode configuration, thereby maintaining efficient current injection while preserving the simplified fabrication benefits

Inventive Principle:

Principle #35Parameter changes

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

The design enables high-density VCSEL arrays with reduced voltage drop and fabrication complexity, enhancing performance and manufacturability, while allowing for independent driving of emitter groups, suitable for applications like 3D sensing and data communication.

Implementation Method 1

a tunnel junction to reverse a carrier type within the bottom mirror structure

Methodology Applied

Scientific EffectTunnel junction:

Implementation Method 2

an oxidation layer to provide optical and electrical confinement of VCSELs of the VCSEL array

Methodology Applied

Scientific EffectOptical confinement:

Data Source

PatentUS12418160B2Vertical-cavity surface-emitting laser array with isolated cathodes and a common anode

Publication Date: 2025.09.16 WELLS FARGO BANK NA

AI summary

A vertical-cavity surface-emitting laser (VCSEL) array may include an n-type substrate layer and an n-type metal on a bottom surface of the n-type substrate layer. The n-type metal may form a common anode for a group of VCSEL. The VCSEL array may include a bottom mirror structure on a top surface of the n-type substrate layer. The bottom mirror structure may include one or more bottom mirror sections and a tunnel junction to reverse a carrier type within the bottom mirror structure. The VCSEL array may include an active region on the bottom mirror structure and an oxidation layer to provide optical and electrical confinement. The VCSEL array may include an n-type top mirror on the active region, a top contact layer over the n-type top mirror, and a top metal on the top contact layer. The top metal may form an isolated cathode for the VCSEL array.