Photonic Integrated Circuit Microwave Radiometer
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Solution Overview
Problem
Conventional microwave radiometers face challenges in providing multi-channel operation due to size, weight, and complexity, making it impractical for hyperspectral measurements, especially in small spacecraft where cost, size, and power constraints are stringent.
Innovation Solution
The integration of an electro-optical receiver with photonic components on a single silicon substrate, enabling up-conversion of microwave signals to the optical domain for processing using photonic integrated circuits, which reduces the size and weight of the instrument while enabling multiple channel operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional microwave radiometer designs with filter banks are used, then multi-channel operation is achieved, but the size, weight, and complexity of the instrument increase significantly
Solution Approach 1:
The patent replaces conventional microwave filter banks with photonic integrated circuits that use optical frequency combs for spectral analysis. This substitution transitions from mechanical/electrical filtering to optical processing, dramatically reducing the physical size and weight while maintaining multi-channel capability. The photonic circuit processes microwave signals by converting them to optical domain, where spectral decomposition occurs through interference patterns rather than physical filter banks.
Solution Approach 2:
The invention changes the operating domain from microwave frequencies to optical frequencies for signal processing. By up-converting microwave signals to optical carrier frequencies and using optical frequency combs, the system achieves spectral resolution through optical interference rather than microwave filtering. This parameter change enables compact hyperspectral sensing because optical components can be integrated on-chip, unlike large microwave filter banks.
2Adaptability or versatility
If hyperspectral measurement capability is implemented at microwave frequencies using conventional methods, then broad spectral range coverage is achieved, but the cost, size, weight, and power requirements become prohibitive for small spacecraft
Solution Approach 1:
The patent replaces bulky microwave hyperspectral sensing components with photonic integrated circuits. The photonic circuit uses optical frequency combs generated by mode-locked lasers and processed through interferometric structures, enabling hyperspectral measurement in a compact form factor suitable for small spacecraft. This substitution reduces weight from kilograms to grams while maintaining spectral coverage.
Solution Approach 2:
The photonic integrated circuit performs multiple functions within a single compact device: signal reception, frequency up-conversion, spectral decomposition, and detection. This multi-functionality consolidates what would traditionally require separate microwave components into one integrated photonic chip, achieving hyperspectral capability without proportionally increasing weight or complexity.
3Measurement precision
If the number of channels is increased in conventional microwave radiometers, then spectral resolution is improved, but the filter bank dimensions and instrument complexity increase proportionally
Solution Approach 1:
The patent replaces physical filter banks with photonic circuits that achieve spectral decomposition through optical interference. The photonic integrated circuit uses frequency comb lines and interferometric structures to resolve spectral features without requiring physical filter elements for each channel. This enables high spectral resolution with minimal physical area because the processing occurs in the optical domain on a chip-scale platform.
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 allows for hyperspectral measurement capabilities in a compact form, reducing the size and weight of microwave radiometers, enabling them to be integrated into smaller spacecraft while maintaining performance, and providing over 50 channels with reduced radio frequency interference sensitivity.
Implementation Method 1
an electro-optic modulator that operates to up-convert received radio frequency (RF) signals to an optical signal
Implementation Method 2
converted to an electrical signal using a photodetector
Data Source
AI summary
Microwave radiometers (MRs) and methods for detecting microwave emissions using an electro-optical receiver that incorporates a photonic integrated circuit are provided. The electro-optical receiver includes an electro-optic modulator that modulates received radio frequency signals onto an optical carrier signal supplied by a pump laser. The resulting upconverted signal, containing the full spectrum of the radio frequency signals, is divided into channels by an optical filter. Each of the channels is connected to a corresponding photodetector, which produces an electrical output having an amplitude that is proportional to the amplitude of the received optical signal. The components included in the photonic integrated circuit can be formed on a single substrate. In addition, the optical filter can filter the received full spectrum optical signal into a large number of channels (e.g. greater than 50).