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An electro-optic ultrafast light source with sub-cycle stability



David R. Carlson, Daniel D. Hickstein, Wei Zhang, Andrew J. Metcalf, Franklyn J. Quinlan, Scott A. Diddams, Scott B. Papp


Optical frequency combs can produce femtosecond light pulses with sub-cycle precision, and are typically made by relying on the intrinsic stability of mode-locked lasers. Now, by carving a continuous-wave laser into pulses via electro-optic modulation (EOM), we report on a new method of controlling optical waves with sub-cycle precision that does not rely on mode locking. This level of stability is enabled by ensuring phase coherence between the microwave-rate modulation and the continuous-wave laser through three techniques: 1) removal of electronic thermal noise using a Fabry-Perot cavity, 2) stabilization of the microwave oscillator using a high-Q microwave cavity, and 3) detection and stabilization of the comb offset frequency after coherent spectral broadening in a silicon-nitride waveguide. In addition to using commercially- available telecommunications and microwave components, the system features deterministic comb formation, repetition rates in excess of 10 GHz, coherent supercontinuum spectra spanning 380 THz (1.9 octaves), few-cycle (15 fs) pulse generation, and sub-cycle pulse-to-pulse timing jitter. Because this level of performance has only been achievable with mode-locked lasers, the EOM comb may offer new features for many emerging and existing applications. Moreover, the spectral broadening and stabilization techniques presented here are widely relevant and could allow inexpensive lasers to be converted into ultrastable sources of femtosecond pulses.
Nature Photonics


electro-optics, nonlinear optics, supercontinuum generation, ultrafast optics


Carlson, D. , Hickstein, D. , Zhang, W. , Metcalf, A. , Quinlan, F. , Diddams, S. and Papp, S. (2018), An electro-optic ultrafast light source with sub-cycle stability, Nature Photonics, [online], (Accessed April 17, 2024)
Created August 8, 2018, Updated February 21, 2019