Multiple frequency combs via pump modulation in a three-mode optomechanical system.

Area of Science:

• Cavity optomechanics
• Nonlinear optics
• Phononics

Background:

• Parametric frequency conversion involving phonons is a key phenomenon in cavity optomechanics.
• Optomechanical systems with coupled resonators offer a platform for studying photon-phonon and phonon-phonon interactions.

Purpose of the Study:

• To exploit parametric frequency conversion to generate multiple frequency combs in a three-mode optomechanical system.
• To investigate the generation of both optical frequency combs (OFCs) and phonon-based frequency combs (PBFCs).

Main Methods:

• Utilizing a three-mode optomechanical system assisted by a degenerate parametric amplifier (DPA).
• Configuring coupled optical-mechanical-mechanical resonators to facilitate photon-phonon and phonon-phonon interactions.
• Satisfying frequency matching conditions for parametric conversion involving photons and phonons.

Main Results:

• Observed generation of OFCs with 1GHz tooth spacing and PBFCs with 80MHz/Nf spacing (integer and fractional orders).
• Demonstrated flexible modulation of comb repetition rate by adjusting mechanical pumps, enabling ultra-small tooth spacing.
• Reported explosive growth of PBFCs with increasing DPA nonlinear gain, forming dense plateau regions with hundreds of comb lines.

Conclusions:

• The proposed method enables the generation of dual optical and phonon-based frequency combs.
• The flexible control over comb spacing and line density holds potential for ultra-high resolution frequency comb applications.
• The findings may advance dual-comb spectroscopy and related high-resolution measurement techniques.