VCSEL Emitter Array Layout for Reduced Emitter Spacing
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Solution Overview
Problem
The spacing between adjacent emitters in vertical cavity surface emitting lasers (VCSELs) cannot be further reduced due to structural limitations, hindering the miniaturization of these devices.
Innovation Solution
The VCSEL design includes a substrate with emitters arranged in an m×n array and a first ohmic metal layer positioned on the surface, where the metal layer is placed in non-light-emitting regions without overlapping with connecting lines between emitters, allowing for reduced spacing between adjacent emitters by using specific mathematical models to optimize the placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the spacing between adjacent emitters is reduced to achieve miniaturization, then the overall dimension of the VCSEL is reduced, but the structural arrangement prevents further reduction of the spacing
Solution Approach 1:
The patent repositions the ohmic metal layer from a conventional planar arrangement to a three-dimensional configuration above the DBR structure. By placing the metal layer at a higher elevation (on the surface of the first DBR) and using diagonal positioning relative to the emitter array, the design exploits the third dimension (vertical height) to resolve the spacing conflict, allowing closer emitter spacing without compromising electrical connection functionality.
Solution Approach 2:
The patent pre-establishes the optimal positioning of the ohmic metal layer during the design phase by defining its projection constraints relative to the connecting lines of emitter centers. This preliminary configuration ensures that the metal layer is positioned to minimize interference with adjacent emitters before the actual device fabrication, enabling the use of smaller spacing from the outset.
2Productivity
If the emitters are arranged in a dense m×n array to improve productivity, then the light-emitting density increases, but the non-light-emitting regions become insufficient for proper metal layer placement
Solution Approach 1:
The patent moves the ohmic metal layer into the vertical dimension by positioning it on the surface of the first DBR at a height above the substrate plane. This elevation allows the metal layer to occupy space that would otherwise be unavailable in the planar non-light-emitting regions, enabling dense emitter arrays while maintaining adequate separation for metal layer placement.
Solution Approach 2:
The patent utilizes the thin film structure of the DBR (Distributed Bragg Reflector) as a platform to support the ohmic metal layer. By placing the metal layer on the DBR surface rather than directly on the substrate, the design effectively uses the DBR thin film structure to provide the necessary spacing and support, allowing dense emitter configurations without compromising the functionality of non-light-emitting regions.
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 effectively reduces the spacing between adjacent emitters, thereby minimizing the overall dimension of the VCSEL, improving its compactness and performance.
Implementation Method 1
Each of the emitters includes a first distributed Bragg reflection (DBR) disposed on the surface of the substrate, an active layer disposed on a side of the first DBR facing away from the substrate, and a second DBR disposed on a side of the active layer facing away from the substrate
Data Source
AI summary
Provided VCSEL including substrate, emitters arranged in m×n array, and first ohmic metal layer. Surface of substrate includes light-emitting regions in array of m rows and n columns and non-light-emitting region surrounding each light-emitting region, m×n≥2. Each emitter includes first DBR on surface of substrate, active layer on side of first DBR away from substrate, and second DBR on side of active layer away from substrate, at least part of first DBR disposed in respective light-emitting region, active layer and second DBR disposed in respective light-emitting region. First ohmic metal layer disposed on surface of first DBR away from substrate and disposed in non-light-emitting region, projection of first ohmic metal layer on substrate doesn't overlap projections of first and second connecting lines on substrate, first and second connecting lines respectively connects centers of emitters in same row, connects centers of emitters in same column.