Silicon Optical Antenna Reflective Layer for Lidar Efficiency
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Solution Overview
Problem
The existing optical antennas for phased array Lidar suffer from low radiation efficiency and significant interference due to the refractive index mismatch between waveguides and free space, leading to reduced scanning angles and performance.
Innovation Solution
A silicon-based optical antenna with a reflective layer is developed, utilizing a silicon-on-insulator substrate with unevenly spaced waveguides and a metal reflective layer between the silicon substrate and buried oxide layer to enhance light coupling into free space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If grating type optical antennas are used for photonic integration, then compatibility with CMOS processes is improved, but radiation efficiency deteriorates due to severe divergence of light coupling
Solution Approach 1:
A reflective layer is introduced as an intermediary component between the grating structure and the substrate. This reflective layer mediates the interaction between light and the substrate by reflecting light that would otherwise be lost, back into the useful optical path, thereby improving radiation efficiency while maintaining CMOS compatibility
Solution Approach 2:
The patent converts the harmful effect of light divergence and energy loss into a beneficial outcome by using the reflective layer to redirect divergent light back toward the useful optical path, transforming energy loss into enhanced radiation efficiency
2Illumination intensity
If metal dipole type optical antennas are used, then near-field optical enhancement is achieved, but outward radiating capacity is limited and substrate compatibility is poor
Solution Approach 1:
The patent changes the fundamental parameters of the antenna structure by transitioning from metal dipole geometry to a silicon-based grating structure with a reflective layer. This parameter change enables compatibility with standard CMOS substrates while maintaining optical enhancement capabilities through the grating-induced diffraction and reflection mechanisms
3Ease of operation
If light is coupled from waveguide into free space, then optical emission is achieved, but emission efficiency deteriorates due to refractive index mismatch
Solution Approach 1:
The reflective layer serves as an intermediary that facilitates the transition of light from the waveguide mode to free space radiation. By reflecting light that would otherwise be trapped or lost, it enhances the coupling efficiency between the waveguide and free space, addressing the refractive index mismatch problem
Solution Approach 2:
The patent introduces a vertical dimension to the optical coupling problem by creating a three-dimensional structure with the reflective layer extending downward from the grating. This dimensional addition provides new pathways for light to escape the waveguide and couple into free space, improving emission efficiency
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 solution significantly improves radiation efficiency by reflecting optical waves back into free space, reducing energy loss and enhancing the scanning capabilities of the optical antenna.
Implementation Method 1
the surface of the buried oxide layer in the groove is formed with a metal reflective layer
Data Source
AI summary
Embodiments of the present disclosure provide a silicon-based optical antenna with a reflective layer and a preparation method therefor. The silicon-based optical antenna comprises: an SOI substrate, the SOI substrate at least comprises a bottom silicon layer, a buried oxide layer, and a top silicon layer, the buried oxide layer is located between the bottom silicon layer and the top silicon layer, the top silicon layer is etched to form a row of waveguides, spacings between the waveguides in the row of the waveguides are in an uneven distribution, each waveguide of the row of the waveguides is etched with gratings, the bottom silicon layer is formed with a groove directly reaching a surface of the buried oxide layer facing the bottom silicon layer, and the surface of the buried oxide layer in the groove is formed with a metal reflective layer.