Metal Pull-Back DBR Grating for Higher-Bandwidth DFB Lasers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing DFB semiconductor lasers lack improved slope efficiency and modulation bandwidth, and their construction is often complex due to varying active layer configurations.
Innovation Solution
The implementation of a metal pull-back grating structure with both pumped and unpumped regions, where unpumped regions act as DBR reflectors and pumped regions act as DFB gratings, along with an identical quantum well active layer extending the device length, simplifying construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional DFB semiconductor laser structure is used, then the device can operate as a laser, but the slope efficiency is limited and modulation bandwidth is restricted
Solution Approach 1:
The laser device is divided into multiple sections along the waveguide: pumped sections containing DFB gratings and unpumped sections acting as DBR reflectors. This segmentation allows different regions to perform specialized functions - the pumped DFB sections provide lasing action with improved slope efficiency, while the unpumped DBR sections provide wavelength selection and feedback, collectively enhancing modulation bandwidth
Solution Approach 2:
Different sections of the waveguide are assigned different functional qualities: pumped regions with DFB gratings for light generation and unpumped regions with DBR gratings for reflection. This local differentiation optimizes each region's performance contribution, with the pumped DFB sections maximizing efficiency and the unpumped DBR sections extending bandwidth capabilities
2Reliability
If a Bragg grating structure is arranged along the waveguide to suppress multiple longitudinal modes, then single mode enhancement is achieved, but the interaction with electromagnetic radiation does not effectively improve slope efficiency
Solution Approach 1:
The grating structure is segmented into DFB gratings in pumped sections and DBR gratings in unpumped sections. The DFB gratings in pumped regions provide distributed feedback for single mode enhancement, while the DBR gratings in unpumped regions provide additional wavelength-selective reflection, together improving both mode purity and slope efficiency
Solution Approach 2:
The unpumped sections with DBR gratings act as intermediary reflective elements between the pumped DFB sections. These DBR sections provide additional feedback pathways that enhance the overall laser efficiency without interfering with the single mode selection function of the DFB gratings
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 enhances slope efficiency and modulation bandwidth while simplifying the manufacturing process of DFB semiconductor lasers.
Implementation Method 1
unpumped regions act as DBR reflectors
Implementation Method 2
DBR reflectors
Implementation Method 3
pumped regions act as DFB gratings
Implementation Method 4
Bragg grating structure
Implementation Method 5
quantum well active layer that extends the length of the device
Data Source
AI summary
Aspects of the present disclosure describe semiconductor DFB laser structures including both pumped and unpumped regions/sections wherein unpumped regions act as DBR reflector(s) while pumped regions act as DFB gratings. Semiconductor DFB laser devices according to aspects of the present disclosure include an active layer that extends the length of the device that is identical in both pumped and unpumped regions/sections.