Subdiffractive pulses in photonic crystals

We show that the diffraction of electromagnetic radiation can disappear in propagation through materials with periodically in space modulated refraction index, i.e. through photonic crystals. We generalize this effect to propagation of light pulses in photonic crystals in the vicinity of the zero-diffraction point. We show that Gaussian pulses spread weakly in space and time during the propagation and the family of nonspreading pulses, propagating invariantly in the vicinity of the zero diffraction point is also found. Other applications of subdiffractive propagation are considered.