Series-Connected VCSEL Array Reduces Parasitic Capacitance
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Solution Overview
Problem
Current VCSEL arrays face limitations in achieving high optical power due to aperture size constraints and additive bulk capacitance in parallel configurations, which can lead to inefficiencies and increased costs in series-connected configurations, particularly in applications requiring precise alignment and wavelength control.
Innovation Solution
A series-connected, single-chip VCSEL array design is implemented, featuring a semiconductor substrate with etched or ion-implanted non-conductive regions to create electrically separate areas, allowing for series connections between VCSEL elements on the same chip, which enhances optical power output and reduces manufacturing and packaging costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If VCSELs are connected in parallel on a common substrate, then the aperture size can be increased, but additive bulk capacitance limits the modulation bandwidth and operational efficiency
Solution Approach 1:
The patent divides the VCSEL array into multiple electrically separate regions on a single chip, with each region containing VCSEL elements that can be independently controlled. This segmentation allows the array to achieve large aperture size while avoiding the bulk capacitance problem of parallel connections by enabling series or independent operation of regions.
Solution Approach 2:
The patent transitions from traditional parallel connection topology to series connection topology, fundamentally changing the electrical configuration dimension. By connecting VCSEL regions in series rather than parallel, the system achieves large aperture size without the additive bulk capacitance that plagues parallel configurations.
2Power
If VCSELs are connected in series using multiple chips tiled on a sub-mount, then the optical power output is enhanced, but the alignment precision and manufacturing complexity increase
Solution Approach 1:
The patent merges multiple VCSEL regions onto a single chip substrate, eliminating the need for tiling multiple chips together. This integration maintains the series connection advantage of high optical power while removing the alignment precision problems associated with multi-chip assemblies.
Solution Approach 2:
The patent introduces etched or ion-implanted non-conductive regions as intermediaries to electrically isolate and series-connect VCSEL regions on the same chip. This intermediary approach enables series connection without requiring physical separation into multiple chips, thereby avoiding alignment issues.
3Power
If VCSELs are connected in series using multiple chips, then the optical power is increased, but the device area and packaging costs increase
Solution Approach 1:
The patent combines multiple VCSEL regions that would traditionally require separate chips into a single integrated chip structure. This merging achieves the high optical power of series connections while minimizing device area by eliminating redundant chip substrates, bonding interfaces, and packaging structures.
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 achieves higher peak optical power from a given current source, reduces parasitic capacitance, and minimizes alignment issues, making it suitable for applications like LiDAR and NIR illumination while maintaining wavelength control and cost-effectiveness.
Implementation Method 1
The conductive layer includes one or more non-conductive regions, formed by etching through the conductive layer or by ion implantation, which create a plurality of electrically separate regions on the conductive layer.
Data Source
AI summary
Methods, devices and systems are described for enabling a series-connected, single chip vertical-cavity surface-emitting laser (VCSEL) array. In one aspect, the single chip includes one or more non-conductive regions one the conductive layer to produce a plurality of electrically separate conductive regions. Each electrically separate region may have a plurality of VCSEL elements, including an anode region and a cathode region connected in series. The chip is connected to a sub-mount with a metallization pattern, which connects each electrically separate region on the conductive layer in series. In one aspect, the metallization pattern connects the anode region of a first electrically separate region to the cathode region of a second electrically separate region. The metallization pattern may also comprise cuts that maintain electrical separation between the anode and cathode regions on each conductive layer region, and that align with the etched regions.