VCSEL Nanostructure Reflector Thermal Management

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Solution Overview

Problem

Vertical cavity surface emitting lasers (VCSELs) face challenges with light control and light emission characteristics due to the limitations of distributed Bragg reflectors (DBRs), which have high thermal resistance and require a lamination structure of multiple layers, leading to inefficiencies in light control and emission.

Innovation Solution

The implementation of a nanostructure reflector with sub-wavelength dimensions, integrated with a distributed Bragg reflector and a gain layer, allows for improved light emission and control characteristics by enhancing reflectance and adjusting the optical properties of VCSELs, enabling selective driving of VCSELs through a network of wiring patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a distributed Bragg reflector (DBR) is used to constitute a laser resonator, then high reflectivity (98% or more) is achieved, but thermal conductivity is reduced due to phonon scattering at material interfaces

Engineering Contradiction:

ImprovereflectivityVSAvoidthermal conductivity

Core Design Contradiction:

Illumination intensityVSTemperature

Solution Approach 1:

The DBR is divided into multiple pairs of layers with different refractive indices. Each interface between layers creates phonon scattering that reduces thermal conductivity, while the collective effect of all interfaces achieves high reflectivity through constructive interference of reflected light waves.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The DBR uses composite structure with alternating layers of materials having different refractive indices (e.g., AlGaAs and GaAs). This composite approach enables high reflectivity through optical interference while the material interfaces inherently create thermal resistance due to phonon scattering.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If a DBR with multiple layered structure is used to achieve high reflectivity, then light emission characteristics are improved, but device complexity increases due to lamination of several tens of layers

Engineering Contradiction:

Improvelight emission characteristicsVSAvoidlamination structure

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The complex multi-layer DBR structure is segmented into repeating units of layer pairs. Each pair contributes equally to the overall reflectivity, allowing the complex structure to be understood and manufactured as repeated simple patterns rather than a single complex assembly.

Inventive Principle:

Principle #1Segmentation

3Productivity

If VCSELs are integrated into an array with wiring patterns for selective driving, then operational flexibility and speed are improved, but manufacturing complexity increases

Engineering Contradiction:

Improveoperational speedVSAvoidwiring pattern integration

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

Multiple wiring patterns (first and second wiring patterns extending in different directions) are merged into a single integrated network that provides both row and column selection capabilities. This combined wiring structure enables selective driving of individual VCSELs while using a unified manufacturing process rather than separate wiring layers.

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 enhances the light emission and control capabilities of VCSELs, improving their efficiency and operational speed while reducing power consumption, making them suitable for various electronic and optical applications.

Implementation Method 1

the nanostructure reflector includes a plurality of nanostructures having a sub-wavelength dimension

Methodology Applied

Scientific EffectSub-wavelength structure effect: Photonic Crystal

Implementation Method 2

The VCSEL includes a distributed Bragg reflector (DBR) having a relatively high reflectivity of about 98% or more for constituting a laser resonator. As the DBR consists of pairs of two materials with different refractive indices

Methodology Applied

Scientific EffectBragg reflection: Bragg Diffraction

Implementation Method 3

Vertical cavity surface emitting lasers (VCSELs) have lower power consumption than edge emitting lasers (EELs) because of a short optical gain length

Methodology Applied

Scientific EffectStimulated emission: Laser

Data Source

PatentUS10938179B2Addressable laser array device including vertical cavity surface emitting lasers adopting nanostructure reflector disposed at intersections of plural wiring patterns

Publication Date: 2021.03.02 SAMSUNG ELECTRONICS CO LTD

AI summary

Provided are an addressable laser array device and an electronic apparatus including the addressable laser array device. The addressable laser array device includes a plurality of VCSELs, each including a distributed Bragg reflector (DBR), a nanostructure reflector including a plurality of nanostructures having a sub-wavelength dimension, and a gain layer disposed between the DBR and the nanostructure reflector; a plurality of first wiring patterns extending in a first direction and being electrically connected to the plurality of VCSELs, respectively; and a plurality of second wiring patterns extending in a second direction intersecting the first direction and being electrically connected to the plurality of VCSELs, respectively, wherein the plurality of VCSELs are disposed at intersections of the plurality of first wiring patterns and the plurality of second wiring patterns, and the addressable VCSEL array device is configured to selectively drive at least some of the plurality of VCSELs.