Photonics-assisted microwave pulse detection and frequency measurement based on pulse replication and...

Area of Science:

• Photonics and Optical Engineering
• Microwave Engineering
• Signal Processing

Background:

• Accurate detection and frequency measurement of microwave pulses are crucial in various applications.
• Existing methods may face challenges with large pulse repetition intervals (PRI) and precise frequency determination.

Purpose of the Study:

• To propose and experimentally validate a novel photonics-assisted scheme for microwave pulse detection and frequency measurement.
• To improve the identification of microwave pulses with large PRIs and accurately measure their carrier frequencies.

Main Methods:

• Conversion of microwave pulses to the optical domain for processing.
• Utilizing a fiber loop for microwave pulse replication to handle large PRIs.
• Employing stimulated Brillouin scattering-based frequency-to-time mapping (FTTM) for carrier frequency measurement.
• Generating a sweep optical carrier modulated by the microwave pulse and a reference signal.

Main Results:

• Successful pulse replication and FTTM were demonstrated for microwave pulses with a 20 µs PRI and varying pulse widths (0.65–1.20 µs).
• Measurement errors were below ±12 MHz (single pulse pair) and ±5 MHz (multiple pulse pairs) under a 0.978 THz/s chirp rate.
• Faster frequency sweep rates increased measurement error, while pulse width had minimal impact at a fixed chirp rate.

Conclusions:

• The proposed photonics-assisted scheme effectively enables microwave pulse detection and accurate frequency measurement.
• The FTTM technique combined with pulse replication offers a robust solution for challenging microwave signal analysis.
• The study highlights the trade-offs between sweep rate, pulse width, and measurement accuracy.