Quantum-Cascade Laser Metal Layer Placement for Heat and Mode Control

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Solution Overview

Problem

Quantum-cascade laser elements face challenges in stabilizing light output by suppressing high-order mode oscillation while improving heat dissipation and yield rate.

Innovation Solution

The quantum-cascade laser element incorporates a semiconductor substrate with a semiconductor laminate featuring a ridge portion, an embedding layer with specific side and edge portions, and a metal layer directly formed on the ridge portion and side surfaces, enhancing heat dissipation and suppressing high-order mode oscillation by strategic placement and direct contact with the active layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a metal layer is formed on the top surface of the ridge portion and insulating layer, then heat dissipation is improved, but high-order mode oscillation cannot be suppressed

Engineering Contradiction:

Improveheat dissipationVSAvoidlight mode stability

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by differentiating the metal layer configuration in different regions: the first metal layer is formed only on the top surface of the ridge portion to suppress high-order mode oscillation, while the second metal layer is formed on the top surface of the insulating layer to enhance heat dissipation. This regional differentiation allows each metal layer to perform its specific function without interfering with the other, resolving the contradiction between heat dissipation and mode stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the metal layer into two distinct parts: a first metal layer on the ridge portion and a second metal layer on the insulating layer. This segmentation allows independent optimization of each layer's function - the first layer for optical mode control and the second layer for thermal management - thereby resolving the technical contradiction between suppressing high-order mode oscillation and improving heat dissipation.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If the metal layer is positioned far from the active layer, then manufacturing is easier, but high-order mode oscillation cannot be effectively suppressed

Engineering Contradiction:

Improvemetal layer positioningVSAvoidhigh-order mode suppression

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by positioning the first metal layer specifically on the top surface of the ridge portion where it can effectively suppress high-order mode oscillation through proximity to the active layer, while the second metal layer is positioned on the insulating layer for heat dissipation. This localized positioning strategy ensures effective high-order mode suppression without compromising manufacturing feasibility.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If additional layers are formed between the metal layer and the ridge portion, then manufacturing flexibility is improved, but yield rate decreases due to manufacturing errors

Engineering Contradiction:

Improvemanufacturing flexibilityVSAvoidyield rate

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent extracts the essential function of suppressing high-order mode oscillation by forming the first metal layer directly on the top surface of the ridge portion, eliminating the need for additional intermediate layers. This direct formation approach removes potential sources of manufacturing errors while maintaining the critical optical function, thereby improving yield rate without sacrificing manufacturing flexibility for the thermal management function performed by the second metal layer.

Inventive Principle:

Principle #2Taking out (Extraction)

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 balances heat dissipation and high-order mode suppression, improving yield rate and stability by ensuring the metal layer is close to the active layer, reducing manufacturing errors' impact, and enhancing bond strength.

Implementation Method 1

the oscillation of the high-order mode can be effectively suppressed by light absorption of the metal layer

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

heat generated in the active layer can be effectively dissipated

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentUS20230139139A1Quantum-cascade laser element and quantum-cascade laser device

Publication Date: 2023.05.04 HAMAMATSU PHOTONICS KK

AI summary

A quantum-cascade laser element includes: an embedding layer including a first portion formed on a side surface of a ridge portion, and a second portion extending from an edge portion of the first portion on a side of a semiconductor substrate along a width direction of the semiconductor substrate; and a metal layer formed at least on a top surface of the ridge portion and on the first portion. A surface of the second portion on a side opposite to the semiconductor substrate is located between a surface of an active layer on a side opposite to the semiconductor substrate and a surface of the active layer on a side of the semiconductor substrate. When viewed in the width direction of the semiconductor substrate, a part of the metal layer on the first portion overlaps the active layer. The metal layer is directly formed on the first portion.