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 performance (e.g., signal-to-noise ratio) detected spectral components. Although previous research has shown that quality generally degrades with an increase in difference between pairs, scaling dual comb systems not been fully characterized. In this Letter, we model characterize a coherent electro-optic system. Our results show at high offset frequencies, is incoherent sum timing two combs, multiplied by line number. At low however, scales more slowly due to coherence common reference.