Generation of Kerr combs centered at 4.5{\mu}m in crystalline microresonators pumped by quantum cascade lasers

TL;DR

This paper demonstrates the generation of mid-infrared Kerr frequency combs at 4.5 micrometers using crystalline microresonators pumped by quantum cascade lasers, achieving the longest wavelength to date with a broad comb spectrum.

Contribution

It presents the first generation of mid-infrared Kerr combs at 4.5 micrometers in high-finesse crystalline microresonators pumped by quantum cascade lasers, with a broad octave-spanning spectrum.

Findings

Achieved Kerr comb generation at 4.5 μm wavelength.

Demonstrated a comb spectrum wider than half an octave.

Used high-Q CaF2 and MgF2 whispering-gallery mode resonators.

Abstract

We report on the generation of mid-infrared Kerr frequency combs in high-finesse CaF$_2$ and MgF$_2$ whispering-gallery mode resonators pumped with continuous wave room temperature quantum cascade lasers. The combs were centered at 4.5$\mu$m, the longest wavelength to date. A frequency comb wider than a half of an octave was demonstrated when approximately 20mW of pump power was coupled to an MgF2 resonator characterized with quality factor exceeding 10$^8$.