Waveguide Structure for Mid-IR Multiwavelength DFB Laser
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Solution Overview
Problem
Concatenated DFB quantum cascade lasers suffer from high losses when unused laser sections are unbiased and high power usage when biased, limiting their power efficiency and wavelength tunability.
Innovation Solution
A waveguide structure that passively guides light out of the gain region and into an adjacent waveguide layer, using non-physically linked optical waveguides to reduce losses and maintain unbiased sections, combined with a superlattice gain material and phase-shifted gratings for enhanced wavelength tunability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If unused laser sections are biased to reduce losses, then wavelength tunability is improved, but power consumption increases
Solution Approach 1:
The laser device is divided into multiple independently controllable laser sections, each capable of operating at different wavelengths. This segmentation allows selective biasing of only the sections needed for current operation, rather than biasing all sections, thereby reducing power consumption while maintaining wavelength tunability across the full spectral range.
Solution Approach 2:
The biasing state of each laser section is dynamically adjusted based on operational requirements. Sections that are currently active are biased to reduce losses, while unused sections remain unbiased to save power. This dynamic control enables the system to adapt power consumption to actual operational needs while maintaining full wavelength tunability.
2Use of energy by moving object
If unused laser sections are left unbiased to reduce power usage, then power efficiency is improved, but losses increase
Solution Approach 1:
By segmenting the laser into independent sections with separate bias control, the invention allows optical losses to be localized only to the necessary active sections rather than affecting the entire device. This segmentation enables unbiased sections to be truly inactive and loss-free while maintaining overall system performance.
Solution Approach 2:
Different biasing conditions are applied to different sections based on their operational status. Active sections receive bias to minimize optical losses, while unused sections remain unbiased to maximize power efficiency. This local differentiation of quality (biasing state) optimizes the trade-off between losses and power efficiency for each section individually.
3Adaptability or versatility
If multiple DFB lasers are concatenated to expand wavelength range, then wavelength tunability is improved, but device complexity increases
Solution Approach 1:
Multiple DFB laser sections are merged into a single integrated device structure with shared common elements such as waveguides, gratings, and substrate. This merging approach achieves the expanded wavelength range of multiple lasers while reducing overall device complexity compared to separate laser devices, as the concatenated structure shares infrastructure and can be fabricated as a single unit.
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 design reduces loss and power consumption while maintaining expanded wavelength tunability, enabling efficient operation and broader spectral coverage for mid-IR applications, such as chemical analysis via infrared spectroscopy.
Implementation Method 1
Distributed feedback ('DFB') lasers are a solid state diode laser technology that incorporates a diffraction grating into the active region of the laser
Implementation Method 2
each lasing section comprises gratings have non-equivalent periods or Bragg wavelengths
Implementation Method 3
the gain material generates photons by intersubband or interband transitions
Implementation Method 4
the gain material generates photons by intersubband or interband transitions
Implementation Method 5
a passive waveguide, wherein each bridge is spatially located between the active waveguide and passive waveguide
Data Source
Figure 1~2
Figure 3~5
Figure 6~6B
AI summary
Concatenated distributed feedback lasers having novel waveguides are disclosed. The waveguides allow for coupling of the laser beam between active and passive waveguide structures and improved device design and output efficiency. Methods of making along with methods of using such devices are also disclosed.