VCSEL Illumination Module Layout for Low-Inductance LIDAR Driving
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Solution Overview
Problem
Existing LIDAR systems with VCSEL arrays face limitations due to high parasitic inductance from numerous wire-bonds, leading to reduced modulation speeds, increased heat generation, and bulkier designs unsuitable for compact applications, along with fragility and integration challenges.
Innovation Solution
The illumination system integrates the optical emitter device and electrical driver on a thermally-conductive ceramic support member, reducing inductance through shorter conductive connections and eliminating the need for extensive wire-bonds, using flip-chip bonding and thermally-conductive materials to enhance heat management and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If numerous wire-bonds are used to connect VCSEL array and electrical driver, then electrical connections are established, but parasitic inductance increases
Solution Approach 1:
The VCSEL array and electrical driver are integrated onto a single ceramic substrate, merging two previously separate components. This integration dramatically shortens the connection paths between electrical contacts, reducing parasitic inductance while maintaining reliable electrical connections through controlled impedance traces on the ceramic substrate.
Solution Approach 2:
The patent transitions from a three-dimensional wire-bonding approach to a planar two-dimensional trace routing on the ceramic substrate. This dimensional change eliminates the need for vertical wire-bonds and replaces them with surface-level conductive paths, significantly reducing inductance while improving thermal management through the substrate plane.
2Speed
If high driving voltage is used to compensate for high parasitic inductance, then modulation speed is maintained, but heat generation increases
Solution Approach 1:
The patent changes the electrical parameters by reducing parasitic inductance through integrated design, which allows operation at lower driving voltages while maintaining the same modulation speed. The controlled impedance traces and shortened connection paths enable high-speed operation with reduced voltage swing, directly lowering power dissipation and heat generation.
3Temperature
If VCSEL array and electrical driver are mounted on separate ceramic sub-mounts, then thermal management is provided, but device footprint increases
Solution Approach 1:
The patent combines the VCSEL array and electrical driver onto a single ceramic substrate, merging their thermal management functions. The unified substrate provides integrated heat sinking for both components, eliminating the need for separate sub-mounts and reducing the overall footprint while maintaining effective thermal dissipation through the ceramic material's high thermal conductivity.
4Ease of operation
If extensive wire-bonds are used for electrical connections, then VCSEL array can be driven, but system fragility increases
Solution Approach 1:
The patent replaces the mechanical wire-bonding system with an integrated circuit trace system fabricated directly on the ceramic substrate. This substitution eliminates fragile wire-bonds that can break under stress, replacing them with robust planar conductors that are mechanically integrated into the substrate structure, significantly improving system robustness while maintaining full driving capability.
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 configuration enhances modulation speed, reduces heat generation, simplifies cooling, and improves reliability, resulting in a more compact and robust LIDAR system with increased range and reduced parasitic inductance.
Implementation Method 1
the support member comprises a thermally-conductive ceramic material
Data Source
AI summary
An illumination module may include an emitter configured to emit light along an optical axis of the illumination module and an optical system located on or over the emitter. The optical system may include a curved surface where the curved surface is tilted in a first direction, such that the optical system introduces optical aberration in the first direction.