Photonic analog-to-digital conversion with equivalent analog prefiltering by shaping sampling pulses

Area of Science:

• Photonics
• Signal Processing
• Analog-to-Digital Conversion

Background:

• Radio frequency (RF) signal digitization is crucial for modern communication systems.
• Traditional methods often require complex hardware for analog filtering.
• Programmable analog prefilters offer a flexible solution for signal conditioning.

Purpose of the Study:

• To propose and demonstrate a novel photonic scheme for digitizing RF signals.
• To enable programmable analog prefiltering by shaping sampling pulses.
• To validate the scheme's principle and operation conditions through modeling and experimentation.

Main Methods:

• Development of a theoretical model for the photonic digitization scheme.
• Derivation of the scheme's operational conditions.
• Experimental demonstration of a four-channel system with program-controlled prefilters.
• Synthesis of bandpass filters with varying phase shifts (0°, 90°, 180°, 270°) by adjusting sampling pulse shapes.

Main Results:

• The filter impulse response is shown to be proportional to the time-reversed sampling pulse shape.
• Successful experimental synthesis of bandpass filters with distinct phase shifts.
• Experimental results align closely with theoretical predictions.
• Demonstrated validity and feasibility of the proposed photonic scheme.

Conclusions:

• The proposed photonic scheme offers a viable method for RF signal digitization with programmable analog prefiltering.
• Adjusting the temporal shape of sampling pulses provides direct control over the filter's impulse response.
• The experimental validation confirms the scheme's potential for flexible and efficient signal processing.