Divide-and-conquer approach to the generation of mid-infrared frequency combs

A novel approach for producing mid-IR frequency combs is based on frequency division, namely transposing the frequency comb of the pump laser to the half of its central frequency in a degenerate optical parametric oscillator (OPO). This approach offers the following major advantages: simplicity of the setup, low (-100 mW) pump power required, potential for high (>; 90%) conversion efficiency where most of the pump photons are converted into subharmonic, and possibility to dramatically exceed the bandwidth of the pump frequency comb, thanks to cross mixing combined with an enormous acceptance bandwidth, typical for type 0 or type 1 OPOs at degeneracy.