Tunable multitap microwave photonic filter with all complex coefficients.

Area of Science:

• Photonics
• Microwave Engineering
• Optical Signal Processing

Background:

• Microwave photonic filters (MPFs) are crucial for advanced signal processing.
• Implementing MPFs with complex coefficients and independent tap control presents significant challenges.

Purpose of the Study:

• To propose and demonstrate a novel architecture for a tunable multitap microwave photonic filter (MPF) capable of implementing all complex coefficients.
• To develop a compact and simplified system for achieving independent control over each filter tap.

Main Methods:

• The architecture utilizes 360° tunable photonic microwave phase shifters based on single-sideband polarization modulation.
• Key components like the polarization modulator, WDM, polarizer, and photodetector are shared across all taps.
• Individual polarization controllers are employed in each tap for independent phase shift adjustment.

Main Results:

• A proof-of-concept experiment successfully realized a four-tap MPF.
• The demonstrated MPF exhibits full free spectral range tunability.
• Adjustable filter shapes were achieved, confirming the system's flexibility.

Conclusions:

• The proposed architecture offers a simple and compact solution for tunable multitap MPFs.
• The use of shared photonic components significantly reduces system complexity and size.
• Independent control of tap phase shifts enables versatile filter shaping and tunability.