Emitter Array Impedance Compensation via Localized Structure Variation
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Solution Overview
Problem
In vertical-emitting device arrays, such as VCSELs, impedance variations along the metallization layer lead to non-uniform optical power output, impacting performance, especially in time-of-flight applications, and increasing the metallization layer size is limited by cost and production constraints.
Innovation Solution
The structure of emitters in the array is varied along the sub-array to compensate for impedance differences, including varying current confinement apertures, implant isolation material, and metal contacts, ensuring emitters receive a threshold voltage, reducing voltage drop and potential failures, and conserving resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metallization layer size is increased to reduce impedance variations, then electrical uniformity improves, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent applies local quality by varying the metallization layer geometry (width, thickness, or trace length) at different positions along the array to compensate for position-dependent impedance variations. This localized modification achieves electrical uniformity without requiring a uniform increase in overall metallization layer size, thus resolving the contradiction between reliability and device complexity.
2Reliability
If emitter structures are varied to compensate for impedance differences, then power distribution uniformity improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs parameter changes by systematically varying emitter structure parameters (such as aperture size, contact area, or layer thickness) along the array to match and compensate for impedance variations. This controlled parameter modification achieves uniform power distribution while maintaining manufacturability through systematic design rules, resolving the contradiction between reliability and manufacturing precision.
3Reliability
If the metallization layer is made larger to accommodate all emitters, then electrical connectivity improves, but production cost increases
Solution Approach 1:
The patent applies local quality by optimizing metallization layer properties only where needed along the array rather than uniformly across the entire structure. This targeted approach maintains electrical connectivity and reduces impedance variations while minimizing the overall metallization material usage and associated manufacturing costs, thus resolving the contradiction between reliability and ease of manufacture.
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 approach improves performance by maintaining consistent voltage across emitters, reducing failures, and conserving costs by allowing for smaller, more efficient emitter arrays with uniform power distribution.
Implementation Method 1
a metallization layer to electrically connect the plurality of VCSELs
Implementation Method 2
impedance variations along the metallization layer lead to non-uniform optical power output
Data Source
AI summary
An emitter array may comprise a plurality of emitters and a metallization layer to electrically connect the plurality of emitters. The metallization layer may have a first end and a second end. The plurality of emitters may include a first emitter and a second emitter. The first emitter may be located closer to the first end than the second emitter. The first emitter and the second emitter have differently sized structures to compensate for a first impedance of the metallization layer between the first end and the first emitter and a second impedance between the first end and the second emitter.