Comb mode filtering silver mirror cavity for spectroscopic distance measurement

Area of Science:

• Optics and Photonics
• Laser Physics
• Frequency Metrology

Background:

• Optical frequency combs are crucial for precise measurements.
• Er-doped fiber lasers offer specific wavelength ranges.
• Increasing repetition frequency enhances comb utility.

Purpose of the Study:

• To design and implement an external optical cavity for an Er-doped fiber frequency comb.
• To enhance the repetition frequency of a 100 MHz optical frequency comb.
• To investigate the application of Fabry-Perot etalons for frequency comb enhancement.

Main Methods:

• Constructed a Fabry-Perot cavity using a transportable cage system with silver mirrors.
• Integrated mode-matching lenses, fiber-coupled collimation, and detection units.
• Employed 3D mirror tilting and adjustable mirror spacing for cavity tuning.

Main Results:

• Demonstrated an increased repetition frequency of the optical frequency comb.
• Verified the frequency increase through direct beat frequency measurements.
• Utilized virtually imaged phased array (VIPA) spectroscopy for spectral analysis.

Conclusions:

• The designed external optical cavity effectively increases the repetition frequency of Er-doped fiber combs.
• Fabry-Perot etalons are suitable for enhancing optical frequency comb repetition rates.
• The implemented system offers precise control and versatile application in metrology.