Theoretical and experimental study of hybrid optical computing engine for arbitrary-order FRFT.

Area of Science:

• Optics and Photonics
• Signal Processing
• Information Theory

Background:

• The Fractional Fourier Transform (FRFT) generalizes the Fourier Transform, offering a new degree of freedom (fractional order).
• FRFT excels in analyzing non-stationary signals where traditional Fourier Transforms are limited.
• Efficient computation of FRFT is crucial for advanced signal processing applications.

Purpose of the Study:

• To develop and demonstrate a hybrid optical system for computing arbitrary-order FRFT of temporal signals.
• To validate the optical system's performance against numerical results.
• To apply the optical FRFT engine for efficient demodulation of chirp spread spectrum signals.

Main Methods:

• A hybrid optical system architecture was designed for real-time FRFT computation.
• Temporal signals were processed, and their fractional-domain information was directly acquired by a detector.
• The system was applied to chirp spread spectrum signal demodulation utilizing sub-Nyquist sampling.

Main Results:

• The optical computing results for arbitrary-order FRFT showed good agreement with numerical simulations.
• The system achieved high compression ratios (as low as 0.4%) in chirp signal demodulation.
• Sub-Nyquist sampling significantly reduced the number of measurements required.

Conclusions:

• The developed hybrid optical system provides an efficient method for arbitrary-order FRFT computation of temporal signals.
• This technology offers unique advantages for non-stationary and chirp-like signal analysis and information extraction.
• The system represents a powerful optical tool for time-frequency analysis and data compression.