Cavity-induced phase noise suppression in a Fabry-Perot modulator-based optical frequency comb

Area of Science:

• Optics
• Photonics
• Frequency Metrology

Background:

• Optical frequency combs are crucial for precise measurements.
• Phase noise in the radio frequency (RF) drive signal can degrade comb performance.
• Fabry-Perot (F-P) cavities are used in some optical frequency comb generators.

Purpose of the Study:

• To investigate the impact of RF drive signal phase noise on F-P modulator-based optical frequency combs.
• To quantify the phase noise suppression effect of the F-P cavity.
• To evaluate the resulting timing jitter improvement.

Main Methods:

• Theoretical modeling of phase noise transfer.
• Experimental generation of optical frequency combs using an F-P modulator.
• Measurement of phase noise spectra for individual comb tones.
• Characterization of timing jitter.

Main Results:

• The F-P cavity partially suppresses RF drive signal phase noise on comb tones.
• Suppression reaches up to 40 dB for high-order tones at high offset frequencies.
• Phase noise suppression is enhanced (up to 10 dB) with low RF power or non-resonant seed laser.
• Timing jitter decreased by a factor of 7 for tones 100 apart.

Conclusions:

• F-P cavity filtering offers significant phase noise reduction for optical frequency combs.
• This technique improves the phase noise of individual comb tones and reduces timing jitter.
• The findings are valuable for applications requiring ultra-low noise optical frequency standards.