Optical Phased Array Wavefront Curvature Compensation
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Solution Overview
Problem
Optical communication systems face cross-coupling issues due to improper pointing of communications terminals, leading to mismatch between wavefront radius of curvature and distance, causing incorrect detection of tilt and positioning errors.
Innovation Solution
The system employs an optical phased array (OPA) architecture to determine and adjust the compensatory wavefront curvature based on distance, wavelength, and aperture sizes between communications terminals, generating a wavefront with a beam waist midway between terminals to correct for cross-coupling, using phase shifters to adjust the wavefront curvature and pointing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a narrow beam is used for high gain in optical communication, then communication throughput and range are improved, but the beam requires accurate active pointing which increases system complexity
Solution Approach 1:
The patent replaces mechanical pointing systems (mirrors, steerable apertures) with an optical phased array that uses electro-optic phase shifting to steer beams. This substitution eliminates moving parts while maintaining beam steering capability, resolving the contradiction between high gain/narrow beam and pointing control complexity
Solution Approach 2:
The patent changes the control parameter from mechanical position to electro-optic phase shift. By controlling the phase of optical signals at each array element, the system can dynamically steer beams and adjust wavefront curvature without mechanical movement, reducing system complexity while maintaining high throughput
2Reliability
If electro-optic phase shifting is used in OPA elements, then beam steering without moving parts is achieved, but cross-coupling occurs due to improper wavefront curvature
Solution Approach 1:
The patent applies preliminary wavefront curvature compensation at the transmitting terminal before beam transmission. By pre-adjusting the wavefront curvature to match the expected propagation distance, the system prevents cross-coupling errors before they occur, ensuring accurate tilt detection and positioning at the receiving terminal
Solution Approach 2:
The patent implements a feedback mechanism where the receiving terminal detects the incoming beam's angle of arrival and wavefront characteristics, then communicates this information back to the transmitting terminal. The transmitting terminal uses this feedback to adjust its phase shifters and wavefront curvature, eliminating cross-coupling and improving measurement precision
3Ease of operation
If wavefront curvature is not compensated, then system operation is simpler, but positioning errors occur due to mismatch between wavefront radius of curvature and distance
Solution Approach 1:
The patent dynamically changes the wavefront curvature parameter based on the communication distance. By calculating the appropriate curvature radius matching the propagation distance and applying it through phase shifter control, the system maintains accurate positioning without overcomplicating operation, as the curvature adjustment is automatically managed
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 ensures accurate pointing and reduces cross-coupling, enhancing the overall performance of optical communication systems by aligning the receiving terminal correctly with the transmitting terminal, thereby improving signal transmission and reception.
Implementation Method 1
Each active element in the OPA requires electro-optic phase shifting capability
Implementation Method 2
generate a wavefront of an outgoing optical communications beam using the plurality of phase shifters
Data Source
AI summary
Aspects of the disclosure provide a system including a first communications terminal. The first communications terminal may include an optical phased array (OPA) including a plurality of phase shifters configured to receive an optical communications beam from a second communications terminal. The first communications terminal may also include one or more processors configured to determine a link axis for communication with the second communications terminal based on the received optical communications beam, identify a compensatory wavefront curvature for mitigating cross-coupling, and generate a wavefront of an outgoing optical communications beam using the plurality of phase shifters based on the determined link axis and the compensatory wavefront curvature.