Photonic-crystal surface emitting laser

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Solution Overview

Problem

Existing photonic-crystal surface emitting lasers face issues with increased threshold current, device resistance, and decreased efficiency, making it difficult to oscillate in a single mode.

Innovation Solution

A photonic-crystal surface emitting laser design featuring a second electrode with a central portion and outer periphery portion, where the central portion has a solid structure with no dielectric film and the outer periphery portion has a mesh structure with dielectric film, creating a refractive index difference to control threshold gain and phase difference, allowing for single-mode oscillation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a conventional photonic-crystal surface emitting laser structure is used, then the device can operate, but the threshold current increases and efficiency decreases

Engineering Contradiction:

Improvethreshold currentVSAvoidefficiency

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The second electrode is designed with spatially varying properties: the central portion has no dielectric film (direct contact with second semiconductor layer) while the outer periphery portion has a dielectric film between the electrode and semiconductor layer. This local quality differentiation creates position-dependent threshold gain, lowering it in the center to favor fundamental mode oscillation and reduce threshold current, while maintaining overall device efficiency.

Inventive Principle:

Principle #3Local quality

2Reliability

If a conventional electrode structure is used, then the device can be manufactured, but higher order modes are not suppressed and single-mode oscillation is difficult to achieve

Engineering Contradiction:

Improvesingle-mode oscillationVSAvoidelectrode structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The electrode structure implements local quality by creating two distinct regions: a central portion with direct electrode-semiconductor contact and an outer periphery portion with dielectric film insulation. This structural differentiation creates corresponding threshold gain differences that suppress higher order modes while maintaining manufacturability through standard fabrication processes.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The dielectric film acts as an intermediary element that selectively insulates the outer periphery portion of the second electrode from the second semiconductor layer. This intermediary creates the necessary threshold gain difference to suppress higher order modes without requiring complete structural redesign, enabling single-mode oscillation while keeping the device manufacturable.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the second electrode is uniformly structured, then manufacturing is simple, but threshold gain cannot be controlled to suppress higher order modes

Engineering Contradiction:

Improvethreshold gain controlVSAvoidelectrode fabrication

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

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

The design effectively suppresses higher order modes and enhances efficiency by ensuring the fundamental mode dominates, reducing threshold current and resistance while maintaining high light intensity.

Implementation Method 1

The photonic crystal layer has a first region and a plurality of second regions each having a refractive index different from a refractive index of the first region

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

At the non-contact portion, the dielectric film is provided between the second electrode and the second semiconductor layer, and the second electrode is separated from the second semiconductor layer

Methodology Applied

Scientific EffectDielectric insulation: Dielectric

Data Source

PatentUS20260018860A1Photonic-crystal surface emitting laser

Publication Date: 2026.01.15 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

A photonic-crystal surface emitting laser includes a first semiconductor layer, an active layer, a photonic crystal layer, a second semiconductor layer, a first electrode, a second electrode and a dielectric film. The photonic crystal layer has a first region and a plurality of second regions. The first electrode has an opening. The second electrode overlaps the opening in a direction. One of a central portion and an outer periphery portion of the second electrode has a contact portion and a non-contact portion. The second electrode is in contact with the second semiconductor layer in the contact portion. In the non-contact portion, the dielectric film is provided between the second electrode and the second semiconductor layer, and in another of the central portion and the outer periphery portion, the second electrode is in contact with the second semiconductor layer.