Silicon Photonics Coupler Structure for Low-Loss LiDAR Links
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Solution Overview
Problem
Existing LIDAR systems face challenges with coupling efficiency, wavelength sensitivity, and link budget performance due to inefficiencies in silicon photonics components.
Innovation Solution
A silicon photonics device is fabricated with a specific structure including a substrate, antennas with grating structures, dielectric layers, and metal layers forming reflective mirrors, along with a method of fabrication using chemical vapor deposition and etching processes to enhance coupling efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional components are implemented on CMOS compatible silicon photonics chips, then device compatibility and integration are improved, but coupling efficiency and link budget performance deteriorate
Solution Approach 1:
The patent modifies the antenna structure parameters by introducing a specific geometric configuration with controlled dimensions (width, length, spacing) and material composition (metal layers with dielectric substrates) to optimize coupling efficiency while maintaining CMOS compatibility. The antenna geometry parameters are tuned to achieve resonance at the target wavelength, resolving the contradiction between manufacturing compatibility and performance.
Solution Approach 2:
The patent employs composite material structures combining metal layers (aluminum, copper, or gold) with dielectric materials (silicon nitride, silicon dioxide) to create antennas that achieve both CMOS process compatibility and enhanced optical coupling efficiency. The composite structure leverages the electrical conductivity of metals and the optical properties of dielectrics to overcome the limitations of single-material implementations.
2Device complexity
If conventional antenna structures are used, then device complexity is reduced, but insertion loss increases and coupling efficiency decreases
Solution Approach 1:
The patent divides the antenna into multiple segmented metal layers separated by dielectric structures, where each segment contributes to the overall resonant response. This segmentation allows for optimized current distribution and reduced ohmic losses while maintaining a relatively simple fabrication process through standard multi-layer deposition techniques.
Solution Approach 2:
The patent introduces dielectric intermediary layers between metal segments and between the antenna and substrate to reduce parasitic losses and improve field confinement. These intermediary dielectric structures act as mediators that enhance coupling efficiency while adding minimal complexity to the device architecture.
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
The device improves coupling efficiency and reduces insertion loss, achieving a 2-6 dB improvement in link budget, making it suitable for automotive-grade LIDAR systems.
Implementation Method 1
The antenna is a one-dimensional grating coupler. The antenna includes a first formation of a first grating structure on top of the substrate member
Implementation Method 2
a diffusion barrier and adhesion layer on top of the first metal layer, the diffusion barrier and adhesion layer and the first metal layer forming a reflective mirror structure
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A structure of a silicon photonics device for LIDAR includes a first insulating structure and a second insulating structure disposed above one or more etched silicon structures overlying a substrate member. A metal layer is disposed above the first insulating structure without a prior deposition of a diffusion barrier and adhesion layer. A thin insulating structure is disposed above the second insulating structure. A first configuration of the metal layer, the first insulating structure and the one or more etched silicon structures forms a free-space coupler. A second configuration of the thin insulating structure above the second insulating structure forms an edge coupler.