Optical Phased Array Calibration Using Near-Field Reference Beam Mixing
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Solution Overview
Problem
Current optical phased array (OPA) calibration techniques are inadequate for large numbers of elements, often relying on pair-wise analysis and being unsuitable for arrays with millions of elements, which limits their effectiveness and scalability.
Innovation Solution
A photonic integrated circuit (PIC)-based calibration technique that generates a mixed optical beam using multiple array elements with phase modulators, captures near-field measurements while scanning phase angles, and generates calibration data to identify phase and amplitude responses, enabling concurrent calibration of multiple elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pair-wise analysis calibration technique is used, then calibration can be performed on individual elements, but the method is unsuitable for arrays with millions of elements and lacks scalability
Solution Approach 1:
The patent combines multiple array elements into groups that are calibrated simultaneously rather than individually. By merging the calibration process for multiple elements into a single measurement operation, the system achieves scalability to millions of elements while maintaining high productivity through parallel processing of grouped elements.
Solution Approach 2:
The patent segments the large array into manageable groups or subsets that can be calibrated concurrently. This segmentation allows the calibration system to handle millions of elements by dividing them into smaller units that can be processed in parallel, resolving the contradiction between scalability and calibration speed.
2Measurement precision
If conventional calibration methods are used, then individual element calibration is possible, but the process is time-consuming and inefficient for large numbers of elements
Solution Approach 1:
The patent implements continuous calibration by capturing near-field measurements across multiple phase angles in a sequential manner that maintains measurement continuity. This approach allows calibration of large numbers of elements without interrupting the measurement process, thereby reducing total calibration time while preserving measurement precision through consistent phase-angle sampling.
Solution Approach 2:
The patent employs periodic phase-angle scanning to calibrate multiple elements simultaneously. By systematically varying the phase angle in periodic steps and capturing measurements at each step, the system achieves both high measurement precision through multiple samples and reduced calibration time through parallel processing of multiple elements across the periodic cycles.
3Productivity
If multiple array elements are calibrated simultaneously, then productivity and scalability improve, but measurement complexity and data processing requirements increase
Solution Approach 1:
The patent introduces a reference beam as an intermediary element that facilitates the simultaneous calibration of multiple array elements. The reference beam serves as a common reference for all elements being calibrated, simplifying the measurement process by providing a stable baseline against which all element responses can be compared, thereby reducing measurement system complexity while maintaining high calibration throughput.
Solution Approach 2:
The patent uses near-field measurements as a copy or representation of the far-field radiation patterns. By measuring and analyzing the near-field electromagnetic distributions, the system can infer far-field characteristics without actually performing far-field measurements, thereby reducing measurement system complexity and enabling simultaneous calibration of multiple elements with simplified hardware while maintaining calibration accuracy.
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 method allows for the simultaneous calibration of large numbers of OPA elements, improving scalability and accuracy, and enables the identification of defective elements, leading to enhanced beam forming and beam steering capabilities.
Implementation Method 1
each array element includes an antenna element and a phase modulator
Implementation Method 2
phase modulators that can be used to compensate for path length differences
Implementation Method 3
The waveguides can be used to transport an optical signal from a source, such as a laser
Implementation Method 4
antenna elements can be used to form beams in specific directions
Data Source
AI summary
A method includes generating a mixed optical beam using an optical phased array that includes multiple array elements, where each array element includes an antenna element and a phase modulator. The mixed optical beam includes a combination of (i) an output optical beam produced by the optical phased array and (ii) a reference optical beam. The method also includes capturing near-field measurements of the mixed optical beam, where the near-field measurements are captured while scanning phase angles of the phase modulators. The method further includes generating calibration data based on the near-field measurements, where the calibration data identifies phase and amplitude responses of the array elements. In addition, the method includes storing the calibration data.