Real-space observation of ultraslow light in photonic crystal waveguides.
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.
Gersen
H
H
Applied Optics Group, Department of Science Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Karle
T J
TJ
Engelen
R J P
RJ
Bogaerts
W
W
Korterik
J P
JP
van Hulst
N F
NF
Krauss
T F
TF
Kuipers
L
L