title: Group delay tuning in active fiber Bragg gratings: from superluminal to subluminal pulse reflection.
abstract: Group delay tuning of optical pulses in pumped asymmetric fiber Bragg gratings below lasing threshold is theoretically proposed. A gain-controlled transition from superluminal to subluminal pulse reflection is analytically investigated in uniform gratings with a pi phase shift and in tapered gratings.
authors.affiliation: Dipartimento di Fisica and Istituto di Fotonica e Nanotecnologie del CNR, Politecnico di Milano, Piazza L. da Vinci 32, I-20133 Milano, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Longhi