Optimized Bragg Reflector Laser Design for Reduced Losses
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Summary
Problems
The performance of quantum cascade lasers with lateral DFB structuring is limited by increased optical losses and reduced electron injection efficiency due to imperfect passivation of lateral flanks and non-radiative recombinations, leading to higher laser thresholds and reduced sensitivity in applications like chemical and biological detection.
Innovation solutions
The laser design features lateral Bragg mirror structuring only above the active region, with periodic corrugations extending from the upper face and a metallic electrode covering the corrugations to enhance optical feedback and electron injection, while maintaining the active region intact, thereby improving reflectivity and injection efficiency.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If lateral DFB structuring is implemented in quantum cascade lasers, then optical feedback and single-mode operation are improved, but optical losses increase and electron injection efficiency decreases
Why choose this principle:
The waveguide is segmented into two distinct zones: an upper section with lateral DFB corrugations for optical feedback and a lower section without corrugations for efficient electron injection. This spatial segmentation allows each zone to optimize its function independently, resolving the contradiction between optical feedback quality and injection efficiency.
Principle concept:
If lateral DFB structuring is implemented in quantum cascade lasers, then optical feedback and single-mode operation are improved, but optical losses increase and electron injection efficiency decreases
Why choose this principle:
Different regions of the waveguide are assigned different structural qualities: the upper region has periodic corrugations with specific geometry optimized for Bragg reflection, while the lower region maintains a smooth profile optimized for electron transport. This local differentiation enables simultaneous optimization of optical and electrical performance.
Application Domain
Data Source
AI summary:
The laser design features lateral Bragg mirror structuring only above the active region, with periodic corrugations extending from the upper face and a metallic electrode covering the corrugations to enhance optical feedback and electron injection, while maintaining the active region intact, thereby improving reflectivity and injection efficiency.
Abstract
The invention relates to a laser comprising a distributed Bragg mirror, said laser being intended to emit monochromatic light radiation along a longitudinal direction (x) and comprising, along a first transverse direction (z) normal to the longitudinal direction (x), a stack (10) of layers based on III-V materials comprising at least one active region configured to emit said monochromatic light radiation, said mirror being formed by periodic lateral corrugations of period Λ along (x), said lateral corrugations extending mainly along (z) and having a dimension d along a second transverse direction (y) normal to the longitudinal direction (x),said laser being characterized in that the lateral corrugations of the Bragg mirror extend from the upper face (110) of the waveguide pattern along the first transverse direction (z) to a height h' strictly less than a depth ha at which at least one active region (13) is located, starting from the upper face (110) of the waveguide pattern, such that a portion (103, 104) of the lateral sides (101, 102) of the waveguide is devoid of lateral corrugations (56) at the level of at least one active region (13). The invention also relates to a method for implementing such a laser.