Tunable, nondispersive optical filter using photonic Hilbert transformation

Area of Science:

• Photonics
• Optical Engineering
• Signal Processing

Background:

• Nondispersive optical filters are crucial for various signal processing applications.
• Existing tunable filters often face limitations in bandwidth range or complexity.
• Complementary filters (band-pass/band-reject) offer versatile spectral shaping capabilities.

Purpose of the Study:

• To propose and numerically demonstrate a new design for tunable nondispersive complementary optical filters.
• To achieve a wide range of bandwidth tunability in optical filtering.
• To integrate photonic Hilbert transformers (PHTs) into a Michelson interferometer (MI) for filter implementation.

Main Methods:

• Numerical demonstration of a novel optical filter design.
• Utilizing two photonic Hilbert transformers (PHTs) integrated into a Michelson interferometer (MI).
• Controlling the central frequencies of the PHTs to tune filter characteristics.
• Employing fiber Bragg grating-based PHTs for feasibility.

Main Results:

• Successful numerical demonstration of a tunable nondispersive complementary optical filter.
• Achieved bandwidth tunability from 260 MHz to 60 GHz.
• Demonstrated a high extinction ratio (>20 dB) and sharp transition slope (170 dB/GHz).
• Central frequency and spectral width of pass/reject bands are tunable by adjusting PHT central frequencies.

Conclusions:

• The proposed design offers a versatile and tunable solution for optical filtering.
• The integration of PHTs within an MI enables wide bandwidth tunability and high performance.
• This approach provides a promising platform for advanced optical signal processing applications.