Optical Phased Array Steering with Lens Array and Phase Shifter
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Solution Overview
Problem
Optical phased array systems face challenges in achieving a wide range of steering angles and good angular resolution with a reasonable number of array elements, as large element spacings result in multiple grating lobes, leading to high power requirements and component size limitations.
Innovation Solution
The system combines a lens array with a large element pitch size, using a coarse beam steering system to focus power into a single grating lobe and a fine beam steering system to control the relative phase of optical signals, allowing for steering within the selected lobe, with options including a translation stage or liquid crystal cell for coarse steering and a phased array controller for fine steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If large element spacings are used in the phased array, then the number of array elements can be reduced, but multiple grating lobes are created causing unwanted beam directions
Solution Approach 1:
A lens array is introduced as an intermediary component between the phased array elements and free space. Each lens corresponds to one or more array elements and focuses the radiated energy into a single desired grating lobe direction, eliminating unwanted lobes while maintaining the benefits of large element spacing
Solution Approach 2:
The lens array provides localized beam shaping where each lens individually controls the radiation pattern of its corresponding array elements. This local control allows each element group to contribute constructively only in the desired direction, suppressing grating lobes locally while maintaining overall system simplicity
2Adaptability or versatility
If close spacing of array elements is used, then a wide range of steering angles is enabled, but the number of array elements increases significantly
Solution Approach 1:
The phased array is segmented into groups, with each group associated with a specific lens. Each segment can be independently controlled to steer beams in different directions, enabling wide angular coverage while maintaining a reduced total number of elements through the lens-based beam shaping
3Measurement precision
If a large number of array elements are used to achieve both wide steering angles and good angular resolution, then system performance is improved, but power requirements become prohibitive
Solution Approach 1:
Multiple array elements are merged into single radiating groups, each served by a common lens. This merging reduces the total number of independently powered elements while the lens ensures that the combined radiation from each group maintains good angular resolution through focused beam formation
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 approach enables efficient steering of optical beams with a reduced number of array elements, minimizing power requirements and component size, while maintaining effective angular resolution and a wide range of steering angles.
Implementation Method 1
The lens array is used to focus all the power into a single grating lobe
Implementation Method 2
The result is constructive and destructive interference in the far field that enable the steering of the beam
Data Source
AI summary
An optical beam steering system comprises an array of optical elements for generating or detecting optical signals, a coarse beam steering system for steering a beam between grating lobes, and a fine beam steering system for steering the beam within a grating lobe imposed by the coarse beam steering system. It can be applied the problem of providing an optical phased array system that has both a wide range of steering angles and good angular resolution with a reasonable number of array elements. By moving the lens array or controlling a liquid crystal cell, power is steered into different grating lobes. Adding a phase shifter for controlling the relative phase of the optical signals corresponding to the optical elements enables steering within the selected lobe.