DFB Laser Grating and Facet Alignment for Stable Phase Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor laser fabrication processes face challenges in achieving stable single-mode output, high yield, and reduced manufacturing complexity and cost, particularly due to issues with precise control of reflective surface phases and grating structures in distributed feedback lasers.
Innovation Solution
A method for fabricating a laser structure involving an epitaxial structure with a substrate, doped dielectric layers, and a multiple quantum well active layer, where a grating structure with periodic grooves and a reflective surface is formed to control the phase of light reflected back to the laser cavity, reducing process complexity and improving stability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional multi-step fabrication processes are used to form grating structures and reflective surfaces, then manufacturing precision can be maintained, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the formation of grating structures and reflective surfaces into a single lithography step by defining both features simultaneously in one photoresist layer. This merging of previously separate fabrication steps reduces process complexity while maintaining the precision needed for phase control, as both structures are patterned together with a single exposure and development cycle.
Solution Approach 2:
The photoresist layer serves multiple functions: it defines both the grating structure pattern and the reflective surface pattern, acts as a mask for subsequent etching steps, and determines the relative positioning of both features. This multi-functionality reduces the number of separate lithography steps needed while maintaining manufacturing precision through unified pattern definition.
2Productivity
If multiple lithography steps are used to define grating grooves and reflective surfaces separately, then manufacturing precision can be maintained, but productivity decreases
Solution Approach 1:
The patent merges the definition of grating grooves and reflective surfaces into a single lithography step, where one photoresist layer defines both features simultaneously. This eliminates the need for separate lithography steps, thereby increasing fabrication throughput while maintaining positioning precision through unified pattern definition in a single exposure process.
3Ease of manufacture
If separate formation steps for grating structures and reflective surfaces are used, then manufacturing flexibility is maintained, but manufacturing cost increases
Solution Approach 1:
The patent combines the formation of grating structures and reflective surfaces into a single lithography and etching sequence, reducing the total number of fabrication steps and associated costs. The unified approach maintains flexibility by allowing both structures to be defined in one mask layer, enabling easy adjustment of their relative positions and dimensions through single-step parameter changes.
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 method enhances the performance and stability of semiconductor lasers by ensuring precise phase control, reducing manufacturing costs, and improving yield and reliability through the formation of a grating structure and reflective surface in a single lithography step, allowing for tailored gain and refractive index modulation.
Implementation Method 1
light reflected back to a laser cavity by the reflective surface having a preset phase
Implementation Method 2
grating structure comprising a plurality of grating grooves periodically spaced along a waveguide direction
Implementation Method 3
the top electrode layer forming an ohmic contact with at least a top surface of each of the preset conductive regions, enabling carriers injected through the top electrode layer to flow through the preset conductive regions
Implementation Method 4
Distributed feedback (DFB) semiconductor lasers are widely deployed in optical communication systems due to their dynamic single mode
Data Source
AI summary
Disclosed are a laser structure and a method for fabricating the laser structure. The method includes: providing an epitaxial structure, the epitaxial structure including a substrate, a first doped dielectric layer, a multiple quantum well active layer and a ridge-shaped doped dielectric layer stacked in sequence; forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflective surface on one end of the grating structure, the reflective surface and the grating structure are defined by a same lithography mask, and the mask is protected in a semiconductor etching process selectively, ensuring that relative positions of the reflective surface and the grating structure are not changed, so that light reflected from the reflective surface back to laser cavity has a predetermined phase defined by design, therefore improves performance and stability of the laser, reduces complexity and cost of the fabrication process, and increases yield and reliability.