3D Optical Phased Array Multi-Layer Si3N4 End-Fire Emission
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Solution Overview
Problem
Traditional integrated optical phased arrays (OPAs) with a single waveguide layer suffer from low light emitting efficiency, limiting their detection range in applications like solid-state LIDAR, as they can only emit a fan-beam and lack the capability for 2D converged beam emission from the edge.
Innovation Solution
A 3D optical phased array based on a multi-layer Si3N4/SiO2 platform is developed, enabling high-efficiency 2D converged beam emission from the edge with improved energy efficiency and steering capabilities, utilizing a structure with 6 Si3N4 layers and 5 SiO2 layers, and employing wavelength tuning for horizontal steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single waveguide layer structure is used, then the device structure is simple, but the light emitting efficiency is low and only fan-beam emission is achieved
Solution Approach 1:
The patent transitions from a 2D single-layer waveguide structure to a 3D multi-layer waveguide structure. By stacking multiple waveguide layers (e.g., 6 Si3N4 layers and 5 SiO2 layers) vertically, the system achieves end-fire emission with 2D converged beam capability, improving light emitting efficiency to up to 82% while maintaining manufacturing feasibility through standardized layer deposition processes.
2Ease of operation
If a single waveguide layer is used, then the phase tuning is convenient, but the beam emission is limited to fan-beam without 2D convergence
Solution Approach 1:
The patent adds the vertical dimension by implementing multiple waveguide layers stacked along the z-axis. Each layer contributes to the phased array, enabling 2D beam convergence and end-fire emission patterns. The phase tuning mechanism is extended to control beams in both horizontal and vertical directions, achieving versatile beam steering while maintaining operational convenience through wavelength tuning.
Solution Approach 2:
The patent employs a nested structure where multiple waveguide layers are stacked vertically, with each layer containing waveguides that are spatially aligned. The layers are nested along the vertical axis, creating a compact 3D phased array structure that achieves 2D beam convergence without requiring large lateral dimensions.
3Loss of energy
If multi-layer structure is implemented, then the light emitting efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent utilizes the vertical dimension to stack multiple waveguide layers, achieving end-fire emission and 2D converged beam with high efficiency (up to 82%). The multi-layer structure consists of alternating Si3N4 and SiO2 layers, where each layer is deposited using standard semiconductor fabrication processes, making the complexity manageable through industrial manufacturing techniques.
Solution Approach 2:
The patent optimizes key parameters of the multi-layer structure, including layer thickness (e.g., 800 nm for Si3N4, 500 nm for SiO2), number of layers (6 Si3N4 and 5 SiO2 layers), and waveguide spacing (2 μm). These parameter optimizations balance the light emitting efficiency improvement with the manufacturing complexity, enabling high-performance devices using existing fabrication capabilities.
4Reliability
If end-fire emission is achieved, then the detection range is extended, but the number of degrees of freedom increases
Solution Approach 1:
The patent achieves end-fire emission by configuring the phased array to emit beams along the lateral edge of the chip rather than vertically upward. The multi-layer structure enables 2D converged beam formation with horizontal steering capability through wavelength tuning. This configuration extends the detection range for LIDAR applications to over 100 m while simplifying the control system by requiring only horizontal beam steering.
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 multi-layer structure achieves an end-fire emitting efficiency of up to 82% and allows for purely horizontal beam steering, enhancing the detection range and efficiency of LIDAR systems while simplifying the operation by reducing the number of degrees of freedom required.
Implementation Method 1
a 3D structure configuration based on multi-layer Si3N4/SiO2 platform is provided to achieve a 2D convergent beam emitted from the edge
Implementation Method 2
the interference of light forms a beam to both its front side and back side
Data Source
AI summary
Beam steering device such as optical phased array (OPA) is a key component in applications of solid-state LIDAR and wireless communication. The traditional single-layer OPA results in a significant energy loss due to the substrate leakage caused by the downward coupling from the grating coupler structure. In the present disclosure, we have investigated a structure based on multi-layers Si3N4/SiO2 platform that can form a 3D OPA to emit the light from the edge of the device with a high efficiency, a 2D converged out-coupling beam will be end-fired to the air. The high efficiency and wide horizontal beam steering are demonstrated numerically, the influence of vertical crosstalk, the delay length, number of waveguide layers, and the fabrication feasibility are also discussed.