DBR Semiconductor Laser with Dielectric Grating Wavelength Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing semiconductor lasers used for wavelength division multiplexing face challenges in accurately controlling oscillation wavelengths due to manufacturing errors in etching compound semiconductors, which affect the depth of diffraction gratings and subsequently the oscillation wavelength of DBR lasers.

Innovation Solution

A semiconductor laser design featuring a first and second distributed-Bragg-reflector region with diffraction gratings made of dielectric material, including recessed portions and convex portions, allowing for precise control of oscillation wavelength by eliminating the need for precise etching control, with the first diffraction grating comprising a dielectric material and the second comprising a semiconductor to adjust reflectivity and threshold gain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If diffraction gratings are formed by etching compound semiconductor at predetermined intervals, then the oscillation wavelength can be controlled, but manufacturing errors cause inaccurate control of the oscillation wavelength

Engineering Contradiction:

Improveetching amount controlVSAvoidoscillation wavelength control

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

A dielectric material layer is introduced as an intermediary between the compound semiconductor substrate and the diffraction grating structure. The dielectric layer serves as a buffer that compensates for etching depth variations, allowing the diffraction grating to maintain its optical function even when the etching amount deviates from the predetermined value, thus decoupling the manufacturing precision requirement from the oscillation wavelength control accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the material parameter of the diffraction grating from pure compound semiconductor to a composite structure involving dielectric material. By adjusting the dielectric layer thickness and refractive index, the system compensates for etching depth variations, transforming the rigid dependency between etching precision and wavelength control into a more flexible system with built-in tolerance

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If the depth of diffraction grating is determined by etching amount, then the manufacturing process is simplified, but the oscillation wavelength deviates from design value due to manufacturing errors

Engineering Contradiction:

Improvediffraction grating formationVSAvoidoscillation wavelength accuracy

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The dielectric material layer is deposited beforehand as a cushioning layer that absorbs the impact of etching depth variations. This layer provides a tolerance buffer that prevents manufacturing errors from directly affecting the diffraction grating's optical performance, ensuring reliable oscillation wavelength control even with simplified manufacturing processes

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The diffraction grating structure is transformed from a single-material compound semiconductor grating to a composite structure involving dielectric material and semiconductor. This composite approach combines the manufacturing ease of dielectric materials with the optical functionality of semiconductor, achieving both simplicity and reliability

Inventive Principle:

Principle #40Composite materials

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 accurately controls the oscillation wavelength of DBR lasers by minimizing manufacturing errors and ensuring the oscillation wavelength remains close to the design value, enhancing the precision and reliability of wavelength multiplexing in high-density applications.

Implementation Method 1

a first diffraction grating including recessed portions formed through a diffraction grating layer formed in the first distributed-Bragg-reflector region and convex portions adjacent to the recessed portions

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

a first distributed-Bragg-reflector region that is formed contiguously with to one side of the active region in a waveguide direction and includes a first diffraction grating

Methodology Applied

Scientific EffectBragg reflection: Bragg Diffraction

Data Source

PatentUS12068579B2Semiconductor laser

Publication Date: 2024.08.20 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

A semiconductor laser includes an active region, a first distributed-Bragg-reflector region disposed contiguously with the active region, and a second distributed-Bragg-reflector region. The first distributed-Bragg-reflector region is formed contiguously with one side of the active region in a waveguide direction and includes a first diffraction grating. The second distributed-Bragg-reflector region is formed contiguously with to the other side of the active region in the waveguide direction and includes a second diffraction grating. The first diffraction grating includes recessed portions formed through a diffraction grating layer formed in the first distributed-Bragg-reflector region and convex portions adjacent to the recessed portions. The diffraction grating layer is made of a dielectric material.