We study the dispersive properties of photonic crystal fibers (PCF's) with
elliptical air holes. The unusual guidance of PCF leads to novel behavior o
f the birefringence, group-velocity walk-off, and dispersion parameters, in
cluding the possibility of zero walk-off with high birefringence in the sin
gle-mode regime. A number of these effects are closely tied to the underlyi
ng radiation states of the air-hole lattice. (C) 2001 Optical Society of Am
erica OCIS codes: 060.2280, 060.2420, 060.2430.