  Photonic crystals doped with resonant atoms allow for uniquely advantageous
nonlinear modes of optical propagation: (a) Self-induced transparency (SIT)
solitons and multi-dimensional localized "bullets" propagating at photonic band
gap frequencies. These modes can exist even at ultraweak intensities (few
photons) and therefore differ substantially either from solitons in
Kerr-nonlinear photonic crystals or from SIT solitons in uniform media. (b)
Cross-coupling between pulses exhibiting electromagnetically induced
transparency (EIT) and SIT gap solitons. We show that extremely strong
correlations (giant cross-phase modulation) can be formed between the two
pulses. These features may find applications in high-fidelity classical and
quantum optical communications.
