Arbitrary-shaped Brillouin microwave photonic filter by manipulating a directly modulated pump

Area of Science:

• Photonics
• Optical Engineering
• Signal Processing

Background:

• Microwave photonic filters are crucial for signal processing.
• Previous methods often involve complex and expensive modulators.
• Stimulated Brillouin scattering (SBS) offers a promising basis for filter implementation.

Purpose of the Study:

• To demonstrate a cost-effective, arbitrary-shaped microwave photonic filter.
• To utilize a directly modulated laser (DML) for precise spectral control.
• To validate the performance of the DML-based SBS filter.

Main Methods:

• Employing stimulated Brillouin scattering in optical fiber.
• Utilizing a directly modulated laser (DML) to shape the optical spectrum.
• Analyzing the relationship between DML modulation current and spectral power density.
• Evaluating filter performance with a 500 Mb/s non-return-to-zero on-off keying signal.

Main Results:

• Achieved gigahertz-wide arbitrary-shaped microwave photonic filtering.
• Demonstrated precise, arbitrary control over the Brillouin filter response for the first time using DML.
• Obtained comparable filter flexibility, shape fidelity, and noise performance to complex IQ modulator approaches.

Conclusions:

• The DML-based SBS filter is a cost-effective and valid solution for microwave photonic applications.
• Arbitrary control of DML optical spectrum enables flexible filter response.
• This technique offers a practical alternative to complex modulator setups.