Edge Emitting Semiconductor Laser Mode Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Broad stripe semiconductor lasers face limitations in beam quality due to excessive peak field strengths causing Catastrophic Optical Mirror Damage (COMD) and deterioration in beam quality from amplification of higher transverse modes, which are not effectively suppressed.
Innovation Solution
An edge emitting semiconductor laser with a structured region in the upper waveguide layer or cladding layer, featuring trenches that selectively dampen higher laser modes while minimizing losses to the fundamental mode, ensuring only the lateral fundamental mode oscillates, thereby enhancing beam quality and output power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the active layer is widened to increase output power, then the output power increases, but the beam quality deteriorates due to amplification of higher transverse modes
Solution Approach 1:
The patent introduces a structured region with periodic refractive index modulations specifically in the edge regions of the waveguide, while the central region maintains uniform properties. This local differentiation creates position-dependent mode discrimination: higher modes experiencing stronger damping in edge regions while the fundamental mode propagates with minimal loss, thus maintaining beam quality at high output powers
Solution Approach 2:
The patent modifies the refractive index distribution by introducing periodic modulations in the structured region, creating a spatially varying parameter profile. This parameter change enables selective coupling suppression for higher modes through resonant interaction with the periodic structure, while the fundamental mode remains uncoupled and propagates efficiently
2Shape
If phase structures are introduced to shape laser modes, then mode selection improves, but device complexity increases
Solution Approach 1:
The patent divides the waveguide into distinct functional regions: a central region with uniform properties for low-loss fundamental mode propagation, and structured edge regions with periodic modulations for higher mode suppression. This segmentation achieves effective mode shaping without requiring complex phase structures throughout the entire waveguide
Solution Approach 2:
The patent extracts the mode-shaping function from the central waveguide region and relocates it to the edge regions through periodic refractive index modulations. This extraction allows the central region to maintain simple, low-loss properties while the edge regions handle the complex mode discrimination function
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 structured region effectively suppresses higher laser modes, achieving high beam quality and efficient coupling into optical fibers with reduced intensity peaks at the side facet, allowing for high output power without COMD, and optimized mode selection.
Implementation Method 1
The lower and upper cladding layers advantageously have a lower refractive index than the waveguide layers into which the active layer is embedded. What is achieved in this way is that the laser radiation is substantially guided in the waveguide core formed from the waveguide layers
Implementation Method 2
The waveguide region advantageously has at least one structured region for mode selection. The structured region is structured in such a way that the lateral fundamental mode of the laser radiation experiences lower losses than the radiation of higher laser modes
Data Source
AI summary
An edge emitting semiconductor laser includes a semiconductor body having a wave guide area. The wave guide area comprises a lower cover layer, a lower wave guide layer, an active layer for generating laser radiation, an upper wave guide layer and an upper cover layer. The wave guide area also includes at least one structured laser radiation scattering area in which a lateral base laser radiation mode experiences less scattering losses than the radiation of higher laser modes.