Waveguide propagation of sub-ps terahertz pulses in single-crystal sapphire
fibers is reported. An incident THz pulse of approximately 0.6 ps duration
undergoes considerable reshaping due to the absorptive and dispersive wave
guide propagation, resulting in transmitted chirped pulse durations of 10-3
0 ps. Good agreement between theory and experiment is obtained by analyzing
the propagation in terms of the single HE11 waveguide mode. The dominance
of the single HE11 mode, despite the fiber dimensions allowing for multimod
e propagation, is attributed to the free-space to waveguide coupling. (C) 2
000 American Institute of Physics. [S0003-6951(00)02215-4].