Two regimes of slow-light losses revealed by adiabatic reduction of group velocity.
The losses in a photonic crystal waveguide were measured with a near-field microscope in the group velocity range of c/7 down to c/200. Our measurements show that the losses scale proportional to v{g};{-2} for group velocities above c/30. Below c/30, the losses are no longer described by the same power-law dependence on v{g} and the modal pattern becomes irregular, indicative of multiple scattering. The findings indicate the existence of two regimes of slow-light losses: one where a perturbative approach describes propagation with fabrication disorder and one where it breaks down.
Center for Nanophotonics, FOM Institute for Atomic and Molecular Physics (AMOLF), Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
R J P
RJ
Engelen
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D
Mori
T
T
Baba
L
L
Kuipers