Quantum Cascade Laser Electrode Routing and Cavity Reflectivity
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Solution Overview
Problem
The existing quantum cascade laser arrays face limitations in flexibility and size due to the arrangement of pad electrodes and laser waveguide structures, which restricts the spacing and length of cavities, affecting the characteristics of the lasers.
Innovation Solution
The quantum cascade laser design includes a substrate with distinct regions and a laser structure featuring laser waveguide structures, electrodes, and wiring metal conductors, allowing the pad electrodes to be independently arranged from the waveguide structures, with the wiring conductors acting as high-reflective films to enhance optical cavity reflectivity and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If pad electrodes are arranged close to laser waveguide structures to reduce chip size, then chip size is reduced, but manufacturing precision and alignment difficulty increase
Solution Approach 1:
The patent introduces wiring metal conductors as intermediary elements that connect pad electrodes to laser waveguide structures. These conductors act as buffer zones that decouple the positional relationship between pad electrodes and waveguide structures, allowing pad electrodes to be positioned away from the optical axis while still providing electrical connection. This intermediary structure resolves the contradiction by enabling both compact chip size and manufacturing precision.
Solution Approach 2:
The patent utilizes the third dimension (vertical layering) to resolve the spatial conflict. By arranging pad electrodes, wiring conductors, and laser waveguide structures in different vertical layers with controlled spacing, the design allows horizontal separation between pad electrodes and waveguide structures while maintaining electrical connection through vertical conductor paths. This dimensional separation enables both reduced chip footprint and improved alignment tolerance.
2Productivity
If spacing between laser waveguide structures is reduced to increase array density, then productivity increases, but optical coupling efficiency and lasing characteristics deteriorate
Solution Approach 1:
The patent applies different structural characteristics to different regions of the laser array. The laser waveguide structures maintain optimized spacing and optical cavity dimensions for reliable lasing, while the pad electrode regions are independently positioned for electrical connection. This local differentiation allows high-density arrays to maintain optimal optical characteristics in the laser regions while achieving high productivity through compact overall布局.
3Area of stationary object
If cavity length is shortened to reduce chip size, then chip size is reduced, but optical reflectivity and lasing efficiency worsen
Solution Approach 1:
The patent introduces distributed Bragg reflectors (DBRs) as intermediary optical structures that provide high reflectivity without requiring long optical cavities. The DBRs are positioned at the ends of the optical cavities and act as optical mirrors with reflectivity exceeding 99%, enabling short-cavity designs to achieve efficient lasing. This intermediary reflective structure resolves the contradiction between compact size and lasing efficiency.
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 enables independent arrangement of pad electrodes and waveguide structures, reducing chip size and power consumption, while improving lasing characteristics by increasing reflectivity and mechanical strength, making it suitable for applications like environmental gas analysis and medical diagnosis.
Implementation Method 1
the wiring conductors acting as high-reflective films to enhance optical cavity reflectivity
Data Source
AI summary
A quantum cascade laser includes a laser structure including laser waveguide structures and a first terrace region; first electrodes; pad electrodes; and wiring metal conductors. The laser structure includes first, second and third regions arranged in a direction of a first axis. The third region is disposed between the first and second regions. The first region has a first end facet disposed at a boundary between the first and third regions. The first end facet extends in a direction intersecting with the first axis. The second region has a second end facet disposed at a boundary between the second and third regions. The second region includes the laser structure. The pad electrodes are disposed on the first terrace region. The first electrodes are disposed on the laser waveguide structures. Each of the pad electrodes is connected to one of the first electrodes through one of the wiring metal conductors.