TY - JOUR AU - Hase, Muneaki AU - Katsuragawa, Masayuki AU - Constantinescu, Anca Monia AU - Petek, Hrvoje PY - 2012 DA - 2012// TI - Frequency comb generation at terahertz frequencies by coherent phonon excitation in silicon T2 - Nat. Photon. JO - Nature Photonics SP - 243–247 VL - 6 KW - fromIPMRAS AB - High-order nonlinear light–matter interactions in gases enable the generation of X-ray and attosecond light pulses, metrology and spectroscopy1. Optical nonlinearities in solid-state materials are particularly interesting for combining optical and electronic functions for high-bandwidth information processing2. Third-order nonlinear optical processes in silicon have been used to process optical signals with bandwidths greater than 1 GHz (ref. 2). However, fundamental physical processes for a silicon-based optical modulator in the terahertz bandwidth range have not yet been explored. Here, we demonstrate ultrafast phononic modulation of the optical index of silicon by irradiation with intense few-cycle femtosecond pulses. The anisotropic reflectivity modulation by the resonant Raman susceptibility at the fundamental frequency of the longitudinal optical phonon of silicon (15.6 THz) generates a frequency comb up to seventh order. All-optical >100 THz frequency comb generation is realized by harnessing the coherent atomic motion of the silicon crystalline lattice at its highest mechanical frequency. N1 - exported from refbase (https://db.rplab.ru/refbase/show.php?record=794), last updated on Wed, 09 May 2012 11:30:28 -0500 ID - Hase_etal2012 ER -