Phase noise of electro-optic dual frequency combs

Dual frequency combs are emerging as new tools for spectroscopy and signal processing. The relative phase noise of the tone pairs determines the performance (e.g., signal-tonoise ratio) of the detected spectral components. Although previous research has shown that the signal quality generally degrades with an increase in frequency difference between tone pairs, the scaling of the relative phase noise of dual frequency comb systems has not been fully characterized. In this Letter, we model and characterize the phase noise of a coherent electro-optic dual frequency comb system. Our results show that at high offset frequencies, the phase noise is an incoherent sum of the timing phase noise of the two combs, multiplied by line number. At lowoffset frequencies, however, the phase noise scales more slowly due to the coherence of the common frequency reference. (C) 2021 Optical Society of America