Semiconductor Laser Waveguide Width Variation for Coupling and Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor laser devices face challenges in reducing the radiation angle of laser light emitted from facets while maintaining optical coupling efficiency, particularly in multi-mode applications where high power is required, and excessive waveguide width reduction leads to reduced optical coupling efficiency.
Innovation Solution
The semiconductor laser device features a waveguide with varying widths along its facets, where the width is narrower between the emission direction front and rear facets, allowing for reduced radiation angles and suppressed higher order modes, while maintaining constant optical coupling efficiency by adjusting the current injection region and coverage width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the waveguide width is increased to reduce optical density at the front facet, then reliability is improved, but optical coupling efficiency to multi-mode fiber is reduced
Solution Approach 1:
The waveguide is designed with different widths at different locations: a wider first waveguide portion at the front facet for reduced optical density and improved reliability, and a narrower second waveguide portion for better optical coupling efficiency. This local variation in geometry allows simultaneous optimization of both reliability and coupling efficiency.
Solution Approach 2:
The waveguide is divided into multiple segments (first waveguide portion and second waveguide portion) with different width characteristics. The first portion has width W1 and the second portion has width W2 where W1 > W2, creating distinct functional zones that resolve the contradiction between reliability and coupling efficiency.
2Reliability
If the waveguide width is excessively increased to improve reliability, then facet damage resistance is improved, but optical coupling efficiency is reduced
Solution Approach 1:
The waveguide implements local quality variation by having a wider first waveguide portion at the front facet for reliability and a narrower second waveguide portion for energy-efficient coupling, avoiding excessive width increase throughout the entire waveguide.
Solution Approach 2:
The waveguide is segmented into portions with different widths, where the first portion (width W1) handles reliability requirements and the second portion (width W2) handles coupling efficiency, preventing unnecessary width increase in the coupling region.
3Ease of manufacture
If the radiation angle is reduced to enable wider waveguide width, then optical coupling efficiency is maintained, but device complexity increases due to anti-waveguiding layer
Solution Approach 1:
The radiation angle is reduced through local geometric modification of the waveguide portions rather than adding complex anti-waveguiding layers, maintaining simplicity while achieving the desired radiation characteristics for efficient coupling.
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 reduces the radiation angle of laser light, enhances reliability by minimizing facet damage, and maintains optical coupling efficiency, improving the semiconductor laser device's performance in multi-mode applications.
Implementation Method 1
a waveguide, in a horizontal direction, is at least partially narrower than a width of the first facet between a first facet of the waveguide on an emission direction front side and a second facet of the waveguide on an emission direction rear side
Data Source
AI summary
A semiconductor laser device of an edge emission type, where a waveguide mode is multi-mode, is provided. The semiconductor laser device includes a first facet of the waveguide on an emission direction front side, the first facet having a first width in a horizontal direction perpendicular to a longitudinal direction of the waveguide; and a second facet of the waveguide on an emission direction rear side, the second facet having the first width, wherein a width of the waveguide, in the horizontal direction, is at least partially narrower than the first width, between the first facet and the second facet.