On-chip Brillouin purification for frequency comb-based coherent optical communications

Area of Science:

• Photonics
• Optical Communications
• Quantum Optics

Background:

• Frequency combs are crucial for optical communications but often suffer from low carrier-to-noise ratios.
• Narrowband amplification and spectral purification are essential for transmitting advanced modulation formats.
• On-chip photonic integration offers advantages in stability and miniaturization over fiber-based systems.

Purpose of the Study:

• To demonstrate the first use of on-chip Brillouin scattering for narrowband amplification and spectral purification of frequency comb lines.
• To enable the transmission of high-capacity data using advanced modulation formats over a photonic chip.
• To showcase the scalability of this approach for wavelength division multiplexing (WDM) applications.

Main Methods:

• Utilizing a parametrically generated optical frequency comb.
• Employing narrowband Brillouin amplification on a photonic chip, using the comb itself as the optical pump.
• Modulating 96 Gb/s data onto multiple comb lines across the 1532.9–1557.5 nm spectrum using 64-level quadrature amplitude modulation (64-QAM).

Main Results:

• Successful transmission of a 64-QAM signal at 96 Gb/s using spectrally purified frequency comb lines.
• Demonstration of narrowband Brillouin amplification and spectral filtering on a chip.
• Achieved data transmission across multiple wavelengths, indicating WDM scalability.

Conclusions:

• On-chip Brillouin scattering is a viable technique for enhancing frequency comb lines for coherent optical communications.
• This photonic chip-based approach enables high-capacity data transmission and offers reduced polarization drift compared to optical fibers.
• The technology paves the way for compact and scalable photonic integrated solutions for future optical networks.