Angled Grating DFB Laser for Single-Wavelength Output
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor laser structures with grating structures face challenges in producing a pure single-wavelength laser due to difficulties in using hologram lithography and requiring additional processes, and they often result in multiple-wavelength oscillation when using quantum dots.
Innovation Solution
A semiconductor laser structure is designed where the longitudinal direction of the ridge waveguide is formed at a predetermined angle with the gratings, utilizing destructive interference to achieve a pure single-wavelength laser, with the angle and grating period optimized to satisfy a λ/4 phase shift and an integer multiple of λ/2, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a distributed feedback semiconductor laser structure with gratings is used to obtain a single-wavelength laser beam, then a single-wavelength laser can be obtained, but additional processes and precise lithography adjustments are required
Solution Approach 1:
The patent applies asymmetry by forming the gratings at a predetermined angle (e.g., 45 degrees) relative to the ridge waveguide rather than parallel to it. This asymmetric configuration enables the gratings to selectively reflect specific wavelengths while allowing other wavelengths to pass through, achieving single-wavelength output without requiring complex additional processing steps or precise lithography adjustments. The angled configuration creates a geometric relationship that inherently provides wavelength selection functionality.
2Power
If quantum dots are used in the active layer to achieve sufficient output, then a multilayer structure and long resonant axis are required, but this results in multiple-wavelength oscillation
Solution Approach 1:
The patent applies local quality by introducing gratings with specific angular orientation at particular locations within the laser structure. These locally positioned angled gratings create selective wavelength reflection zones that suppress multiple-wavelength oscillation while maintaining the multilayer quantum dot structure needed for sufficient output power. The gratings are strategically placed to provide wavelength selection without requiring changes to the quantum dot active layer configuration.
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 approach allows for the production of a high-output single-wavelength laser without additional processing steps, reducing costs and improving yield, as it simplifies the fabrication process and eliminates the need for precise lithography adjustments.
Implementation Method 1
utilizing destructive interference to achieve a pure single-wavelength laser
Implementation Method 2
a plurality of gratings formed in at least one of the first and second clad layers, making a predetermined angle with the first ridge waveguide or the second ridge waveguide, and periodically arranged in a longitudinal direction
Data Source
AI summary
Provided is a distributed feedback semiconductor laser structure including: a first clad layer; a first ridge waveguide formed on the first clad layer; an active layer formed on the first ridge waveguide; a second ridge waveguide formed on the active layer; a second clad layer formed on the second ridge waveguide; an ohmic contact layer formed on the second clad layer; and a plurality of gratings formed in at least one of the first and second clad layers, making a predetermined angle with the first ridge waveguide or the second ridge waveguide, and periodically arranged in a longitudinal direction of the first or second ridge waveguide. As a result, a general hologram lithography process capable of mass production is applied to the present invention so that process time can be reduced. Also, a distributed feedback semiconductor laser structure using a quantum-dot active layer that does not require an additional process for obtaining a pure single-wavelength is provided.