Compact and ultrastable photonic microwave oscillator

Area of Science:

• Physics
• Optical Engineering
• Metrology

Background:

• Microwave synthesis traditionally relies on bulky tabletop systems.
• Achieving ultrastable microwave generation is crucial for advanced scientific applications.

Purpose of the Study:

• To demonstrate state-of-the-art ultrastable microwave synthesis using a compact, rack-mountable apparatus.
• To characterize the phase noise performance of the synthesized microwave signal.

Main Methods:

• Utilized an ultrastable laser at ~194 THz and an Er:fiber frequency comb divider.
• Employed semiconductor coating mirrors for transportable optical frequency references.
• Performed absolute phase noise characterization of a 12 GHz synthesized signal.

Main Results:

• Achieved phase noise of -83 dBc/Hz at 1 Hz offset and < -166 dBc/Hz for offsets > 5 kHz.
• Demonstrated a residual noise limit of -115 dBc/Hz at 1 Hz for the division and detection process.
• Showcased the potential for -105 dBc/Hz at 1 Hz using semiconductor coating mirrors.

Conclusions:

• The compact apparatus enables high-fidelity microwave synthesis outside controlled laboratory environments.
• This technology supports the development of portable ultrastable photonic microwave oscillators.
• Facilitates the operation of next-generation transportable optical clocks with enhanced precision.