LiDAR Light Receiver Array Using Photonic Crystal Slow Waveguides
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Solution Overview
Problem
LiDAR devices using slow light waveguides face challenges in increasing signal strength due to high propagation loss and limited reception area, which reduces the effectiveness of receiving reflected light from a wide range of arrival angles.
Innovation Solution
A light receiver array is formed by array-aligning plural receivers with photonic crystal slow waveguides, where the alignment and orientation of receivers are optimized to receive reflected light in the same phase, and the length of the slow light waveguide is limited to the unsaturated region to minimize propagation loss, enhancing signal strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the length of the slow light waveguide is increased to expand the reception area, then the reception area is improved, but the propagation loss increases
Solution Approach 1:
The receiver is divided into multiple receiver elements (first receiver element and second receiver element) with individual slow light waveguides. Each element has an optimized length that avoids excessive propagation loss while collectively providing expanded reception area coverage. The segmentation allows each waveguide to be kept relatively short (avoiding saturation region) while the array configuration achieves the overall large reception area goal.
2Adaptability or versatility
If the alignment pitch of receivers is increased to receive reflected light from a wider range of angles, then the reception angle range is improved, but the phase consistency of received light deteriorates
Solution Approach 1:
Each receiver element is designed with specific local characteristics (individual alignment pitches and orientations) optimized for different angle ranges. The first receiver element and second receiver element have different alignment pitches tailored to their respective optimal reception angles. This local optimization allows the system to maintain phase consistency within each element's designated angle range while collectively covering a broader overall angle range.
3Area of stationary object
If multiple receivers are array-aligned to increase reception area, then the reception area is improved, but the device complexity increases
Solution Approach 1:
Multiple receiver elements with individual slow light waveguides are merged into a single integrated light receiver array structure. The receivers are array-aligned with their slow light waveguides extending in the same direction, creating a unified device that functions as one coherent reception system. This merging approach achieves expanded reception area while managing device complexity through systematic integration rather than disparate separate components.
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 optimized receiver array significantly increases the signal strength of reception signals by reducing propagation loss and improving the reception area, allowing for more efficient detection of reflected light across a wider range of angles.
Implementation Method 1
The slow light is generated in a photonic nanostructure like a photonic crystal waveguide, has a low group speed, and significantly changes a propagation constant by slight change of wavelength and refractive index of the waveguide.
Implementation Method 2
When the diffraction mechanism is provided inside or immediately near the slow light waveguide, the slow light waveguide is coupled to the diffraction mechanism into a leakage waveguide, so as to emit light in a free space.
Data Source
AI summary
A light receiver array according to the present invention is constituted by array-aligning plural receivers having slow light waveguides of photonic crystals, and a LiDAR device according to the present invention is constituted by linearly arranging a light receiver array and a transmitter. An arranging relationship of plural receivers of the light receiver array is an array-like element formed by array-aligning plural receivers having the slow light waveguides of photonic crystals, and the array alignment is defined by alignment for defining a position relationship between the plural receivers constituting the light receiver array, and orientation for defining a direction of each receiver. A relationship p=λ/sin Δθr is satisfied between the alignment pitch p, wavelength λ of the reception light, and an arrival angle Δθr when a phase difference between reception lights received by waveguide ends of adjacent receivers is one wavelength. Such a constitution that the arrival angle Δθr is equal to a widening angle Δθt of radiation light is suitable.