Lidar Receiver Die Isolation Trenches for Stray Light Rejection
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Solution Overview
Problem
LIDAR systems face reduced detection accuracy due to stray light incident on photodetectors from misaligned couplings and leakages, which can be picked up by light-sensitive devices, leading to reduced fidelity and increased power consumption.
Innovation Solution
The implementation of optical isolation trenches, such as airgap and filled trenches, is introduced to absorb, block, or reflect stray light, forming spatial relationships with light-sensitive devices to prevent direct light paths, thereby reducing stray light incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical isolation trenches are implemented to block stray light, then detection fidelity is improved, but device complexity increases
Solution Approach 1:
The optical isolation structure is segmented into multiple trenches arranged in a pattern around the photodetector. Each trench acts as an independent light-blocking element, and collectively they form a comprehensive isolation barrier. This segmentation allows the system to achieve effective stray light rejection while maintaining a manageable structural complexity through modular design.
Solution Approach 2:
The optical isolation trenches serve as intermediary structures between the signal path and stray light sources. These trenches act as mediators that intercept and block stray light before it reaches the photodetector, thereby protecting the detection system without requiring direct modification of the photodetector itself or complete system redesign.
2Measurement precision
If optical isolation trenches are added to reduce stray light, then detection accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The optical isolation trenches are formed as part of the preliminary fabrication steps during semiconductor manufacturing. By integrating the trench formation into the existing manufacturing process flow rather than adding it as a separate post-processing step, the system achieves effective stray light isolation without significantly increasing overall manufacturing complexity or cost.
Solution Approach 2:
The optical isolation effect is achieved by controlling specific parameters of the trenches such as their depth, width, spacing, and fill material properties. By optimizing these geometric and material parameters, the system achieves effective stray light blocking using standard manufacturing capabilities, avoiding the need for exotic or highly complex fabrication techniques.
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 enhances detection fidelity and reduces power consumption by minimizing stray light interference, allowing for improved detection accuracy and efficient operation of LIDAR systems.
Implementation Method 1
The trenches can prevent a direct path for light through the receiver die
Implementation Method 2
The trenches may be an airgap trench (e.g., filled with air, or alternatively a vacuum or other substance immediately surrounding the substrate), or a filled trench filled with some light-absorbing material
Data Source
AI summary
A LIDAR system for a vehicle can include a receiver die having one or more light sensitive components and one or more optical isolation trenches configured to optically isolate the one or more light sensitive components on the receiver die; wherein the one or more optical isolation trenches are arranged such that light does not pass in a direct path through the receiver die.