Generation of optical frequency combs with a CaF2 resonator

Area of Science:

• Nonlinear optics
• Resonator optics
• Quantum optics

Background:

• Optical frequency combs are crucial for precision measurement.
• Whispering gallery mode resonators offer high Q-factors and small mode volumes.
• Fluorite is a promising material for nonlinear optical applications.

Purpose of the Study:

• To demonstrate optical frequency combs using a fluorite whispering gallery mode resonator.
• To investigate different generation regimes and their associated repetition rates.
• To explore novel phenomena like Raman lasing in this system.

Main Methods:

• Utilizing a fluorite whispering gallery mode resonator as the nonlinear Kerr medium.
• Generating optical frequency combs through nonlinear processes within the resonator.
• Analyzing the generated spectra to identify different generation regimes and characteristics.

Main Results:

• Successfully generated optical frequency combs with two distinct regimes.
• Achieved a record low repetition rate of 13 GHz, matching the cavity's free spectral range (FSR).
• Observed high repetition rates as multiples of the FSR, along with an intermediate regime.
• Reported the first observation of Raman lasing spectra similar to modulation instability in fibers.

Conclusions:

• Fluorite whispering gallery mode resonators are effective for generating optical frequency combs.
• The study reveals unique comb generation dynamics and a record low repetition rate.
• The observation of Raman lasing opens new avenues for nonlinear optics research.