Stacked VCSEL Module Layout for Faster Pulse Current Switching
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Solution Overview
Problem
Current VCSEL modules lack integration of a switching element and a VCSEL in a miniaturized form, which affects the rising and falling times of the pulse current, impacting the accuracy and efficiency of range finding devices.
Innovation Solution
A VCSEL module with a three-stage stacked structure, including a VCSEL, a switching element, and a substrate, where the switching element and VCSEL are integrated with a current control element, and a capacitor for improved current flow and reduced inductance, enabling faster rising and falling times of the pulse current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional VCSEL module structure is used, then the module size is larger, but the rising and falling times of pulse current are longer which reduces range finding accuracy
Solution Approach 1:
The patent combines the VCSEL and switching element into a single integrated module structure, where the VCSEL is mounted directly on the switching element in a stacked configuration. This merging eliminates separate mounting structures and reduces the overall current path length, thereby minimizing inductance and achieving rising/falling times of 1 nanosecond or less while maintaining compact size.
Solution Approach 2:
The patent transitions from a planar layout to a three-dimensional stacked structure, arranging the VCSEL and switching element vertically in multiple layers. This dimensional change allows for shorter current paths and reduced inductance while maintaining a compact footprint, directly addressing the time loss issue without increasing module size.
2Speed
If the VCSEL and switching element are separated, then the module structure is simpler, but the inductance increases causing slower pulse current response
Solution Approach 1:
The VCSEL and switching element are merged into a single integrated package with direct electrical and thermal coupling. The VCSEL is mounted directly on the switching element's surface, creating a compact structure where the current path is minimized, thereby achieving nanosecond-level rising and falling times despite the increased structural integration.
Solution Approach 2:
The patent employs a nested stacked structure where the VCSEL is positioned on top of the switching element, with both components sharing a common substrate and thermal management structure. This nesting arrangement minimizes the distance between components and reduces overall inductance while maintaining a manageable structural complexity through modular design.
3Loss of time
If a miniaturized integrated structure is used, then the rising and falling times are reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent segments the integrated module into distinct functional layers (substrate, switching element, VCSEL) that can be manufactured and tested separately before final assembly. This segmentation allows each component to be optimized independently while maintaining the compact stacked structure, thereby reducing rising/falling times without excessively complicating the overall manufacturing process.
Solution Approach 2:
The switching element and VCSEL are prepared and positioned in advance during the manufacturing process, with pre-formed electrical connections and mounting structures. This preliminary preparation enables the final assembly to be completed efficiently, achieving the miniaturized integrated structure with minimized inductance while keeping the manufacturing process manageable through standardized procedures.
Data Source
AI summary
A VCSEL module includes a VCSEL, a switching element disposed below the VCSEL and electrically connected to the VCSEL, and a substrate disposed below the switching element, and electrically connected to the switching element.