Photonic Integrated Circuit for Co-Boresighted Optical and RF Phased Arrays
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Solution Overview
Problem
Existing RF phased arrays face challenges due to their large volume and weight, which are overcome by using an optical feed network to transfer phase and amplitude directly to microwave signals, but this requires a common architecture for both optical and RF phased arrays to achieve co-boresighted beams for applications like mobile data links and 5G communications.
Innovation Solution
A photonic integrated circuit (PIC) provides a common architecture for both optical and RF phased arrays, using an optical feed network to split and phase-modulate optical signals, converting them to RF electrical feed signals with photo-detectors, and integrating switches to redirect optical power between optical and RF antennas, ensuring co-boresighted beams within a specified angular tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If RF phased arrays are used to achieve beam steering capability, then the beam steering function is provided, but the volume and weight of the system become large
Solution Approach 1:
The patent replaces the traditional RF-electronic beamforming network with an optical feed network. Optical components such as optical waveguides, optical phase modulators, and optical splitters are used to perform beamforming functions that were previously accomplished with large RF electronics. This substitution of optical for RF-electronic systems dramatically reduces the volume and weight while maintaining beam steering capability.
Solution Approach 2:
The patent creates a dual-function system where a single optical feed network serves both optical phased array (OPA) and RF phased array (RPA) functions. The same optical components can generate steerable optical beams and, through coherent detection with microwave signals, generate steerable RF beams. This multi-functionality eliminates the need for separate beamforming networks for optical and RF systems.
2Volume of moving object
If optical feed network is used to reduce volume and weight, then the size is reduced, but a common architecture for both optical and RF phased arrays is required to achieve co-boresighted beams
Solution Approach 1:
The patent designs a unified optical feed network architecture that can serve dual purposes: generating optical beams for optical phased arrays and generating RF beams for RF phased arrays through coherent detection. The same optical waveguides, phase modulators, and splitters are used for both functions, requiring careful design to achieve co-boresighted beams but eliminating the need for separate optical and RF beamforming networks.
Solution Approach 2:
The patent uses optical signals as an intermediary to connect and coordinate the optical and RF phased array systems. By using the optical feed network as a common platform and employing coherent detection techniques, the system achieves synchronization and co-boresighting between optical and RF beams without requiring completely separate architectures.
3Reliability
If separate optical and RF phased arrays are used, then independent optimization is possible, but the system volume and weight increase
Solution Approach 1:
The patent merges the optical phased array and RF phased array systems into a single integrated platform sharing common optical feed network infrastructure. By combining the two systems and sharing optical components such as waveguides, phase modulators, and splitters, the patent reduces overall system weight and volume while maintaining the ability to independently optimize optical and RF beamforming through the shared architecture.
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
The PIC enables the generation of steerable and co-boresighted optical and RF beams, improving the reliability and data rate of links by aligning optical and RF beams tightly, suitable for applications in guidance, autonomous vehicles, and 5G communications, while reducing the size and weight of the system.
Implementation Method 1
The principle of operation uses a coherent detection scheme to directly transfer the phase and amplitude of an optical signal to a microwave signal by mixing this signal with an optical local oscillator (LO) signal.
Implementation Method 2
If the optical frequency of the LO signal differs by 10 GHz from the input signal than a 10 GHz microwave signal with the same phase and amplitude as the optical signal will be obtained after combination and detection of the two signals.
Implementation Method 3
A plurality of switches selectively re-direct the phase-shifted first optical channel signals to feed a respective plurality of optical antennas to produce a steerable optical beam. The photo-detectors and RF antenna elements may also be integrated on the PIC.
Data Source
AI summary
A photonic integrated circuit (PIC) provides a common architecture to feed both optical and RF phased arrays to produce steerable co-boresighted optical and RF beams from a single chip. The PIC may be used for guidance, mobile data links, autonomous vehicles and 5G cellular communications. A plurality of switches are monolithically fabricated on the PIC with the optical feed network to switch the optical power of the phase-modulated optical channel signals between the integrated optical antennas and the RF antennas to produce steerable optical and RF beams. The photo-detectors and RF antennas may be discrete components or integrated with the optical feed network. To ensure that the optical and RF beams are co-boresighted (within a specified angular tolerance) for the same steering commands, the PIC is positioned within the RF antenna array footprint.