Tunable microwave frequency comb generation using a Si₃N₄-MDR based actively mode-locked OEO.

Area of Science:

• Photonics
• Microwave Engineering
• Optical Engineering

Background:

• Microwave frequency combs (MFCs) are crucial for advanced communication and sensing due to their numerous lines, wide frequency range, and precise spacing.
• Existing MFCs often require fixed parameters, limiting their adaptability to diverse operating bands and accuracy needs.

Purpose of the Study:

• To develop a tunable MFC generator capable of adjusting its center frequency and comb spacing.
• To enhance the flexibility of MFCs for varied communication and sensing applications.

Main Methods:

• A tunable optoelectronic oscillator (OEO) was employed as the core MFC generator.
• A low-frequency electrical signal was injected into the tunable OEO to control MFC parameters.
• A silicon nitride micro-disk resonator (Si₃N₄-MDR) was integrated to facilitate system miniaturization.

Main Results:

• The MFC generator demonstrated a wide frequency tuning range from 1 to 22 GHz.
• The system successfully produced 50 comb lines within a 5 MHz bandwidth.
• Tunable center frequency and variable comb spacing were achieved.

Conclusions:

• The developed tunable MFC generator offers enhanced flexibility for communication and sensing.
• The integration of Si₃N₄-MDR shows promise for compact and integrated MFC systems.