A single source microwave photonic filter using a novel single-mode fiber to multimode fiber coupling technique

Area of Science:

• Photonics
• Microwave Engineering
• Signal Processing

Background:

• Microwave photonic filters (MPFs) are crucial for high-frequency signal processing.
• Existing MPFs often require multiple laser sources or complex configurations.
• Tunability and reconfigurability are key challenges in MPF development.

Purpose of the Study:

• To present a fully tunable and reconfigurable single-laser multi-tap microwave photonic Finite Impulse Response (FIR) filter.
• To demonstrate the efficacy of a single-mode to multi-mode (SM-to-MM) optical combiner for incoherent signal summing in FIR filters.
• To validate the filter's performance through experimental demonstration.

Main Methods:

• Utilizing a single laser source for all filter taps.
• Employing a passive single-mode to multi-mode (SM-to-MM) optical combiner for incoherent signal summation.
• Experimentally implementing and testing an eight-tap FIR filter with programmable coefficients.

Main Results:

• Successful demonstration of an eight-tap microwave photonic FIR filter.
• Achieved excellent correspondence between predicted and measured filter responses.
• Observed clean and accurate magnitude response across the entire bandwidth.
• Validated the phase-insensitive and interference-free operation of the SM-to-MM combiner.

Conclusions:

• The proposed single-laser multi-tap microwave photonic FIR filter is fully tunable and reconfigurable.
• The SM-to-MM combiner is an effective component for incoherent signal summing in such filters.
• This approach offers a simplified and robust solution for advanced microwave photonic filtering applications.