Optical Phased Array Antenna Layout for Low-Reflection LiDAR Emission
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Solution Overview
Problem
The transmission efficiency of edge-emitting antennas in optical phased arrays is severely affected by significant reflection due to refractive index changes when light is transmitted from the chip into free space, necessitating a solution to improve this efficiency.
Innovation Solution
The proposed antenna array includes N phase compensation groups and N antenna groups, where each phase compensation group consists of M phase compensation units and each antenna group has M antenna units. The antenna units feature waveguide-based mode converters that gradually change width to expand the light spot for emission, and phase compensation units with conic or parabolic shapes adjust the phase shifts caused by the antenna units, ensuring arithmetically distributed phases of emitted optical signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a wide waveguide is used at the edge of the chip to properly confine light, then light confinement is improved, but transmission efficiency deteriorates due to significant reflection from refractive index change
Solution Approach 1:
The patent introduces a gradual width transition of the waveguide from the chip interior toward the edge, transforming the abrupt one-dimensional interface into a continuous dimensional gradient. This gradual transition in the width dimension reduces the sudden refractive index change, thereby minimizing reflection losses while maintaining light confinement throughout the waveguide structure.
Solution Approach 2:
The patent changes the waveguide width parameter gradually from a constant wide dimension to a tapered profile that decreases toward the chip edge. This parameter change creates a smooth impedance transition, reducing the reflection coefficient at the interface between the waveguide and free space, thus improving transmission efficiency while preserving light confinement in the bulk of the waveguide.
2Loss of energy
If the waveguide width is reduced to enlarge the light spot for emission, then transmission efficiency is improved, but light confinement deteriorates
Solution Approach 1:
The patent applies dimensional transition by creating a tapered waveguide where the width gradually changes from wide (for confinement) to narrow (for emission). This spatial variation in the width dimension allows the waveguide to simultaneously provide strong confinement in its wide section and effective light spot expansion in its narrow section, resolving the contradiction between confinement and transmission efficiency.
Solution Approach 2:
The waveguide can be conceptually segmented into different functional zones: a wide-section zone for light confinement and propagation, and a narrow-tip zone for light spot expansion and emission. This segmentation allows each zone to optimize its local function while contributing to the overall system performance, balancing confinement and transmission 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
This configuration reduces reflection by enlarging the light spot and compensating for phase differences, thereby enhancing transmission efficiency and meeting requirements for far-field imaging.
Implementation Method 1
The antenna unit includes a waveguide-based mode converter changing gradually from a first width to a narrower second width. The antenna unit is configured to gradually expand a light spot in the waveguide for emission from a tip end.
Implementation Method 2
An output end is connected to an antenna unit in the antenna group, is configured to transmit the received optical signal to the antenna unit, and performs phase compensation on the optical signal based on a phase shift caused by the antenna unit.
Implementation Method 3
When the light reaches the edge of the chip for transmission into free space, a significant reflection phenomenon immediately occurs due to a sudden change in a refractive index
Data Source
AI summary
Embodiments of the present disclosure disclose an antenna array applied to an optical phased array, the optical phased array, and a LiDAR. The antenna array includes N phase compensation groups and N antenna groups, where each phase compensation group includes M phase compensation units, and each antenna group includes M antenna units, and where N and M are positive integers. An input end of a phase compensation unit in the phase compensation group is configured to receive an optical signal. An output end is connected to an antenna unit in the antenna group, is configured to transmit the received optical signal to the antenna unit, and performs phase compensation on the optical signal based on a phase shift caused by the antenna unit. The antenna unit is configured to transmit the optical signal.