Optical Phased Array Wavefront Control Using Orthogonal Dithering
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Solution Overview
Problem
Optical phased arrays (OPAs) in wireless communication systems face challenges in maintaining beam alignment due to static and dynamic variables such as path length mismatch, optical aberrations, and atmospheric turbulence, leading to reduced power and intensity of optical communications beams.
Innovation Solution
Implementing frequency-division (FD) and time-division (TD) mode dithering with orthogonal sets of functions to adjust phase shifters in subsets of the OPA, using perturbations to optimize phase shifts and enhance beam power and intensity by iteratively correcting phase shifter values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time optimization of individual phase shifters is performed, then beam alignment accuracy is improved, but system complexity and processing time increase significantly
Solution Approach 1:
The patent divides the large set of phase shifters into multiple smaller subsets that can be processed independently and in parallel. This segmentation allows the system to optimize individual phase shifter groups without being overwhelmed by the total number of elements, reducing processing complexity while maintaining alignment accuracy.
Solution Approach 2:
Instead of optimizing all phase shifters simultaneously, the patent applies dithering to only a subset of phase shifters at each iteration. This partial action approach reduces the computational burden per iteration while still achieving effective beam alignment through cumulative adjustments across multiple iterations.
2Productivity
If dithering is applied to all phase shifters simultaneously, then optimization speed is improved, but signal interference and measurement accuracy deteriorate
Solution Approach 1:
The patent segments the phase shifters into distinct subsets that are dithered separately rather than all at once. This segmentation prevents the dither signals from overlapping and interfering with each other, maintaining measurement accuracy while still achieving parallel optimization across multiple subsets.
Solution Approach 2:
The patent employs periodic dithering with carefully selected frequencies for different subsets. By using periodic actions at different frequencies, the system can distinguish between the effects of different subset dithers and avoid interference, maintaining signal measurement accuracy while optimizing multiple subsets efficiently.
3Productivity
If frequency-division dithering is used, then parallel processing capability is improved, but frequency management complexity increases
Solution Approach 1:
The patent utilizes frequency as a distinguishing parameter for different phase shifter subsets. By assigning different frequencies to different subsets, the system enables parallel processing through frequency-division multiplexing. The frequency management complexity is handled through systematic allocation and correlation techniques that track which frequency corresponds to which subset.
4Measurement precision
If the narrow beam is actively pointed using small mirrors, then beam alignment is improved, but mechanical complexity and cost increase
Solution Approach 1:
The patent replaces mechanical beam steering mechanisms (small mirrors) with an optical phased array that uses electro-optic phase shifting. This substitution eliminates moving parts and mechanical complexity while achieving beam alignment through electronic control of phase shifters, reducing cost and improving reliability.
Solution Approach 2:
The patent controls beam direction by changing the phase parameter of light waves across the array elements rather than physically moving mirrors. This parameter-based control (electronic phase modulation) replaces mechanical positioning, achieving the same alignment function without mechanical complexity.
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
Enhances beam power and intensity by quickly adapting to dynamic changes, improving signal strength and steering accuracy in optical communications.
Implementation Method 1
performing a plurality of dithers iteratively on the plurality of subsets of phase shifters
Implementation Method 2
identifying a plurality of subsets of phase shifters of the plurality of phase shifters based on an orthogonal set of functions
Implementation Method 3
Each active element in the OPA requires electro-optic phase shifting capability
Implementation Method 4
compensating for static and dynamic variables like path length mismatch, optical aberrations, and atmospheric turbulence
Data Source
AI summary
Aspects of the disclosure provide a method of adjusting a plurality of phase shifters of an OPA. The method may include identifying a plurality of subsets of phase shifters of the plurality of phase shifters based on an orthogonal set of functions; performing a plurality of dithers iteratively on the plurality of subsets of phase shifters of the plurality of phase shifters using the same frequency; determining a plurality of corrections based on a plurality of outputs of the OPA, each output resulting from each of the plurality of dithers; and adjusting the plurality of subsets of phase shifters of the plurality of phase shifters using the plurality of corrections, the adjustment resulting in at least one set of corrected phase shifter values.