Tunable triangular frequency modulated microwave waveform generation with improved linearity using an optically...

Area of Science:

• Photonics
• Microwave Engineering
• Signal Processing

Background:

• Generating linear frequency modulated (FM) microwave waveforms is crucial for radar and communication systems.
• Traditional methods often face limitations in linearity, tunability, and complexity.
• Optically controlled microwave signal generation offers a promising alternative.

Purpose of the Study:

• To propose and demonstrate a photonic approach for generating linear triangular FM microwave waveforms.
• To enhance waveform linearity using a generalized regression neural network (GRNN).
• To investigate the tunability of waveform parameters and assess performance in reducing range-Doppler coupling.

Main Methods:

• Utilizing an optically injected semiconductor laser operating in the period-one oscillation state.
• Controlling optical injection strength to shape the output into a triangular waveform.
• Employing a GRNN for post-processing to improve linearity.
• Adjusting parameters of the low-frequency electrical triangular control signal for tunability.

Main Results:

• Successfully generated a triangular FM microwave waveform with a frequency range of 14-24 GHz and a duration of 2 μs.
• Experimentally verified significant improvement in waveform linearity.
• Demonstrated tunability of center frequency, bandwidth, and time duration.
• Analyzed ambiguity functions, confirming reduced range-Doppler coupling.

Conclusions:

• The proposed photonic approach effectively generates linear triangular FM microwave waveforms.
• The GRNN-based method enhances waveform linearity.
• The demonstrated tunability and performance improvements make this technique suitable for advanced radar and communication systems.