Photonic integrated circuit implementation of a sub-GHz-selectivity frequency comb filter for optical clock...

Area of Science:

• Photonics
• Integrated Optics
• Optical Signal Processing

Background:

• Optical clock multipliers and frequency comb filters are crucial for high-speed optical communication and signal processing.
• Existing solutions often face challenges with complexity, size, and reconfigurability.

Purpose of the Study:

• To demonstrate a novel photonic integrated circuit for optical clock multiplication.
• To implement a reconfigurable optical frequency comb filter with high selectivity and low complexity.

Main Methods:

• Design and fabrication of a ring-resonator-assisted asymmetrical Mach-Zehnder interferometer in a Sagnac loop.
• Utilizing a high-index-contrast stoichiometric silicon nitride (Si3N4/SiO2) waveguide platform.
• Experimental characterization of the filter's passband and demonstration of repetition rate multiplication.

Main Results:

• Achieved a sub-GHz selectivity with a -3-dB bandwidth of 0.6 GHz and a -20-dB bandwidth of 1.2 GHz.
• Demonstrated five-fold repetition rate multiplication of optical clock signals (e.g., 2.5 Gpulses/s to 12.5 Gpulses/s).
• The device exhibits low loss, small size, and large bandwidth.

Conclusions:

• The developed photonic integrated circuit offers a device-compact solution for optical clock multipliers and frequency comb filters.
• This technology has potential applications in RF spectrum scanners, photonic radars, WDM switches, and LIDARs.
• The novel circuit topology enables efficient comb spectrum processing on an integrated platform.