Improving the accuracy of a dual-comb interferometer by suppressing the relative linewidth

Abstract

We present a compact system of synchronization for two fiber-based optical frequency comb lasers. We use a free-running continuous wave laser as an intermediary to obtain the relative noise of two combs and employ an intra-cavity electro-optic modulator (EOM) to achieve active phase feedback for fast synchronization. The EOM bandwidth is 150 kHz and the relative linewidth is suppressed markedly from 300 kHz to sub-hertz values. The relative effective timing jitter of the two pulse trains is also decreased from 680 fs to 25 fs. The proposed method shows promise for developing a high-performance, low-cost, fiber-based dual-comb interferometer for ranging or spectroscopy.

Impact of Laser Intensity Noise on Dual-Comb Absolute Ranging Precision

“…The absolute ranging capability based on OFCs can be further improved by adopting a dual-comb configuration [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. The principle is similar to the linear optical sampling (LOS) used in optical telecommunication systems [ 34 , 35 ].…”

“…High precision absolute ranging frequently benefits from higher repetition rate femtosecond laser sources [ 19 , 20 ]. The repetition rate gap [ 21 , 22 , 23 ] between the two mode-locked lasers has an impact on the fringe density of interferometric beat notes, thus affecting the ranging precision indirectly [ 24 ]. The center wavelength of the overlapping part of the spectra of the two optical frequency combs indirectly affects the ranging precision in a similar manner [ 25 ].…”