Monolithic SiPM Array Isolation for Low Cross-Talk Receiver Channels
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Solution Overview
Problem
Existing optical systems, such as LIDAR devices, face challenges in efficiently integrating and aligning multiple silicon photomultipliers (SiPMs) with aperture arrays to form receiver channels, which can lead to increased complexity and potential cross-talk between SiPMs.
Innovation Solution
The optical system integrates multiple SiPMs monolithically on a single substrate, with each SiPM comprising numerous single photon avalanche diodes (SPADs). The system includes an aperture array aligned with the SiPMs to define receiver channels, and additional features like isolation trenches and a baffle structure provide electrical and optical isolation to reduce cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple SiPMs are integrated on a single substrate, then device complexity is reduced and manufacturing is simplified, but cross-talk between SiPMs increases
Solution Approach 1:
The substrate is divided into multiple discrete SiPM regions separated by isolation trenches. Each SiPM is electrically and optically isolated from others through these trenches, allowing multiple photomultipliers to coexist on a single substrate without significant cross-talk. This segmentation enables simplified integration while maintaining signal integrity between individual SiPMs.
Solution Approach 2:
Optical elements such as microlenses and aperture arrays are positioned between the SiPMs and the target object to control light paths. These intermediary elements ensure that light reaching each SiPM comes only from its designated field of view, preventing optical cross-talk between adjacent SiPMs while maintaining the benefits of monolithic integration.
2Productivity
If aperture array is aligned with SiPM array to define receiver channels, then receiver channel efficiency is improved, but alignment precision requirements increase
Solution Approach 1:
The aperture array and SiPM array are designed with pre-established geometric relationships and registration features that guide alignment during assembly. By preparing alignment marks and defining channel geometries in advance, the system achieves efficient receiver channels without requiring extremely high precision alignment procedures during manufacturing.
Solution Approach 2:
The system optimizes parameters such as aperture size, SiPM pitch, and focal lengths to create a robust alignment tolerance window. By carefully selecting these parameters, the design achieves high receiver channel efficiency while maintaining relaxed alignment requirements that are practical for manufacturing.
3Object-generated harmful factors
If isolation trenches are added between SiPMs, then cross-talk is reduced, but device complexity and manufacturing steps increase
Solution Approach 1:
The isolation trenches serve dual purposes: they provide electrical isolation between SiPMs and simultaneously act as structural support elements for the substrate. By combining multiple functions into a single feature, the design reduces cross-talk without proportionally increasing device complexity. The trenches are integrated into the substrate fabrication process rather than added as separate complex 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 approach simplifies the fabrication of optical systems by integrating multiple SiPMs on a single substrate, reduces cross-talk between SiPMs through isolation techniques, and enhances the efficiency of receiver channels, leading to improved performance in optical systems like LIDAR devices.
Implementation Method 1
Each SiPM includes a plurality of single photon avalanche diodes (SPADs)
Implementation Method 2
A monolithic SiPM array includes a plurality of silicon photomultipliers (SiPMs) monolithically integrated with the substrate... at least one isolation trench in the substrate, wherein the at least one isolation trench is arranged between neighboring SiPMs
Implementation Method 3
additional features like isolation trenches and a baffle structure provide electrical and optical isolation to reduce cross-talk
Data Source
AI summary
An optical system may include a substrate and a plurality of silicon photomultipliers (SiPMs) monolithically integrated with the substrate. Each SiPM may include a plurality of single photon avalanche diodes (SPADs). The optical system also includes an aperture array having a plurality of apertures. The plurality of SiPMs and the aperture array are aligned so as to define a plurality of receiver channels. Each receiver channel includes a respective SiPM of the plurality of SiPMs optically coupled to a respective aperture of the plurality of apertures.