title: Real-space observation of ultraslow light in photonic crystal waveguides.
abstract: We show the real-space observation of fast and slow pulses propagating inside a photonic crystal waveguide by time-resolved near-field scanning optical microscopy. Local phase and group velocities of modes are measured. For a specific optical frequency we observe a localized pattern associated with a flat band in the dispersion diagram. During at least 3 ps, movement of this field is hardly discernible: its group velocity would be at most c/1000. The huge trapping times without the use of a cavity reveal new perspectives for dispersion and time control within photonic crystals.
authors.affiliation: Applied Optics Group, Department of Science Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Gersen
authors.forename: T J
authors.initials: TJ
authors.lastname: Karle
authors.forename: R J P
authors.initials: RJ
authors.lastname: Engelen
authors.forename: W
authors.initials: W
authors.lastname: Bogaerts
authors.forename: J P
authors.initials: JP
authors.lastname: Korterik
authors.forename: N F
authors.initials: NF
authors.lastname: van Hulst
authors.forename: T F
authors.initials: TF
authors.lastname: Krauss
authors.forename: L
authors.initials: L
authors.lastname: Kuipers