title: Superluminal optical pulse propagation at 1.5 microm in periodic fiber Bragg gratings.
abstract: We report on the experimental observation of superluminal tunneling of picosecond optical pulses in a periodic fiber Bragg grating. Optical pulses of 380-ps duration, generated by an externally-modulated single-frequency erbium-ytterbium laser operating near 1.5-microm wavelength, were propagated at a group velocity greater than approximately 1.97 times the speed of light in vacuum across a 2-cm long fiber grating. Owing to the very large ratio between the thickness of the barrier (2 cm) and the wavelength of probing optical pulses ( approximately 1.5 microm), our experiment allows for the observation of superluminal tunneling in the optical region by direct optoelectronic time-domain measurements.
authors.affiliation: Istituto Nazionale per la Fisica della Materia, Dipartimento di Fisica, Politecnico di Milano, Piazza L. da Vinci 32, I-20133 Milano, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Longhi
authors.forename: M
authors.initials: M
authors.lastname: Marano
authors.forename: P
authors.initials: P
authors.lastname: Laporta
authors.forename: M
authors.initials: M
authors.lastname: Belmonte