title: Mode coherence measurements across a 1.5 THz spectral bandwidth of a passively mode-locked quantum dash laser.
abstract: The mode coherence of adjacent and non-adjacent spectral modes of a passively mode locked quantum dash (QDash) semiconductor laser are deduced through radio frequency beat-tone linewidth measurements. A wavelength conversion scheme that uses degenerate four wave mixing in a semiconductor optical amplifier is proposed which considerably extends the mode spacing beyond the limit imposed by conventional fast-photodetection and electrical spectrum analysis of around 100 GHz. Using this scheme, the mode coherence of the QDash laser was measured out to the thirty-first harmonic, or a mode separation of 1.5 THz.
authors.affiliation: The Rince Institute, School of Electronic Engineering, Dublin City University, Dublin 9, Ireland. regan.watts@dcu.ie
authors.forename: Regan
authors.initials: R
authors.lastname: Watts
authors.forename: Ricardo
authors.initials: R
authors.lastname: Rosales
authors.forename: Francois
authors.initials: F
authors.lastname: Lelarge
authors.forename: Abderrahim
authors.initials: A
authors.lastname: Ramdane
authors.forename: Liam
authors.initials: L
authors.lastname: Barry