Photonic Nyquist folding receiver using optical pulses with discrete pulse position modulation.

Area of Science:

• Photonics
• Optical Engineering
• Signal Processing

Background:

• Ultra-wideband (UWB) radio frequency (RF) signal acquisition demands high-speed sampling, leading to complex and costly hardware.
• Conventional compressive sensing techniques for UWB signals often involve high computational complexity.

Purpose of the Study:

• To present a novel photonic Nyquist folding receiver (NYFR) architecture for efficient UWB RF signal acquisition.
• To demonstrate a system that reduces hardware complexity by utilizing photonic components and under-sampling.

Main Methods:

• Integration of a mode-locked laser (MLL) and Mach-Zehnder modulators (MZMs) to generate non-uniform optical pulse trains for sampling.
• Employing optical pulse compression and under-sampling with a low-speed analog-to-digital converter (ADC).
• Utilizing digital signal processing for reconstructing the original RF signal from folded spectral components.

Main Results:

• Successful recovery of RF signals up to 7 GHz using a 15-GHz optical pulse train and a 2-GS/s digitizer.
• Demonstrated robustness in reconstructing dual-tone and chirped signals across multiple Nyquist zones.
• Achieved superior performance in broadband RF signal acquisition with reduced complexity compared to conventional methods.

Conclusions:

• The proposed photonic NYFR architecture effectively enables efficient UWB RF signal acquisition and processing.
• The system offers a significant reduction in hardware complexity and computational load.
• Potential applications span communications, radar, and electronic warfare systems.