Optical frequency comb noise spectra analysis using an asymmetric fiber delay line interferometer

Area of Science:

• Optics and Photonics
• Laser Physics
• Metrology

Background:

• Optical frequency combs (OFCs) are crucial for precise frequency measurements.
• Characterizing noise in OFCs is essential for improving their performance.
• Existing methods for noise analysis can be complex and limited.

Purpose of the Study:

• To develop a simple and practical apparatus for high-precision noise measurements in OFCs.
• To analyze the noise performance and identify dominant noise sources in an Er-fiber OFC.
• To investigate the dynamics of noise in mode-locked lasers and OFCs.

Main Methods:

• Established a novel apparatus for measuring repetition rate (frep) noise and carrier-envelope frequency (fceo) noise spectra.
• Utilized a fiber delay line interferometer for frep and optical comb mode (νn) noise measurements.
• Employed an f-2f interferometer for fceo noise spectrum measurements.

Main Results:

• Successfully characterized the noise performance of an Er-fiber OFC.
• Identified the origins of dominant noise sources within the OFC.
• Uncovered an anti-correlation between frep and fceo noise.
• Demonstrated the impact of servo loops on noise characteristics in a stabilized OFC.

Conclusions:

• The developed apparatus is a powerful tool for diagnosing noise dynamics in mode-locked lasers and OFCs.
• Understanding noise correlations and the effect of stabilization is key to advancing OFC technology.
• This work facilitates improved precision and stability in optical frequency metrology.