Optical Phased Array Digital Holography Phasing
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Solution Overview
Problem
Next-generation optical phased arrays (OPAs) designed using photonic integrated circuits (PICs) face challenges in efficiently controlling the phases of large numbers of array elements for beam shaping and beam pointing, particularly in achieving simultaneous phasing and calibration of numerous elements.
Innovation Solution
The implementation of a digital holography-based phasing technique using a local oscillator on the photonic integrated circuit, which allows for the measurement and adjustment of relative phases among array elements, enabling them to be brought into a simultaneously-phased state, and a multi-stage calibration approach for precise phase control and identification of defective elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional phase control methods are used for large numbers of array elements, then individual phase adjustment is possible, but the complexity of control and calibration increases significantly
Solution Approach 1:
The patent introduces a local oscillator antenna element as an intermediary reference that all other array elements can be calibrated against. This mediator enables simultaneous phasing of numerous elements through a common reference point, dramatically simplifying the control architecture compared to traditional pairwise or sequential calibration methods.
Solution Approach 2:
The system performs preliminary calibration by first establishing the local oscillator as a phase reference, then uses this pre-established reference to quickly calibrate all other array elements. This preliminary setup action eliminates the need for complex real-time phase coordination during operation.
2Manufacturing precision
If digital holography is used for phasing control, then simultaneous phasing of array elements is achieved, but measurement and processing requirements increase
Solution Approach 1:
The system uses the array elements themselves to generate the measurement signals needed for their own calibration. By having array elements transmit signals that are received and measured by the local oscillator, the system performs self-calibration without requiring external calibration equipment or complex external measurement setups.
Solution Approach 2:
The digital holography process provides feedback information about the relative phases of array elements by measuring their signals against the local oscillator reference. This feedback is then used to adjust the phase modulators, creating a closed-loop system that continuously optimizes phasing accuracy.
3Productivity
If more array elements are added to increase data rate, then communication capacity increases, but the time and resources required for calibration increase
Solution Approach 1:
The local oscillator serves as a pre-established phase reference that remains constant during operation. This preliminary calibration reference allows new array elements to be quickly integrated and calibrated without requiring re-calibration of the entire system, enabling scalable expansion while maintaining constant calibration time.
Solution Approach 2:
The calibration process is segmented into two independent stages: (1) establishing the local oscillator as a phase reference, and (2) calibrating array elements against this reference. This segmentation allows the reference establishment to be performed once, while individual array elements can be calibrated independently and in parallel, enabling linear scaling with array size.
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 solution enables efficient beam forming and beam steering with high slew rates, adaptive optics compensation, and large data rate increases, while reducing size, weight, and power consumption, and supporting scalable and cost-effective production.
Implementation Method 1
The additional antenna element is configured to function as a local oscillator and generate a reference optical signal for digital holography-based phasing control of the optical phased array
Implementation Method 2
the phase modulator are configured to modulate the optical signals transmitted by the antenna elements
Implementation Method 3
performing digital holography using the measurements to identify relative phases of the array elements with respect to a phase of the additional antenna element
Data Source
AI summary
A method includes capturing measurements of optical signals transmitted from an optical phased array that includes (i) multiple array elements each having an antenna element and a phase modulator and (ii) an additional antenna element spaced apart from the array elements. The method also includes performing digital holography using the measurements to identify relative phases of the array elements with respect to a phase of the additional antenna element. In addition, the method includes modifying phases provided by at least some of the phase modulators of at least some of the array elements to bring the array elements more closely into phase with one another.