. Finally, which can be investigated by using a probe beam with a larger intensity, might also reveal interesting phenomena. ACKNOWLEDGMENTS We acknowledge support from the Alexander von Humboldt foundation, the DFG and the REA (program COSCALI, No. PIRSES-GA, 2010.

G. Rempe, R. J. Thompson, R. J. Brecha, W. D. Lee, and H. J. Kimble, Optical bistability and photon statistics in cavity quantum electrodynamics, Physical Review Letters, vol.67, issue.13, p.1727, 1991.
DOI : 10.1103/PhysRevLett.67.1727

A. Lambrecht, T. Coudreau, A. M. Steinberg, and E. Giacobino, Squeezing with cold atoms, Europhysics Letters (EPL), vol.36, issue.2, p.93, 1996.
DOI : 10.1209/epl/i1996-00192-1
URL : http://arxiv.org/abs/quant-ph/9801051

D. Budker, Resonant nonlinear magneto-optical effects in atoms, Reviews of Modern Physics, vol.74, issue.4, p.1153, 2002.
DOI : 10.1103/RevModPhys.74.1153

A. M. Dawes, L. Illing, S. M. Clark, and D. J. Gauthier, All-Optical Switching in Rubidium Vapor, Science, vol.308, issue.5722, p.672, 2005.
DOI : 10.1126/science.1110151

D. M. Bloom, P. F. Liao, and N. P. Economou, Observation of amplified reflection by degenerate four-wave mixing in atomic sodium vapor, Optics Letters, vol.2, issue.3, p.58, 1978.
DOI : 10.1364/OL.2.000058

M. Vallet, M. Pinard, and G. Grynberg, Generation of Twin Photon Beams in a Ring Four-Wave Mixing Oscillator, Europhysics Letters (EPL), vol.11, issue.8, p.739, 1990.
DOI : 10.1209/0295-5075/11/8/008

V. Boyer, A. M. Marino, R. C. Pooser, and P. D. Lett, Entangled Images from Four-Wave Mixing, Science, vol.321, issue.5888, p.544, 2008.
DOI : 10.1126/science.1158275

M. Pinard, D. Grandclement, and G. Grynberg, Continuous-Wave Self-Oscillation Using Pair Production of Photons in Four-Wave Mixing in Sodium, Europhysics Letters (EPL), vol.2, issue.10, p.755, 1986.
DOI : 10.1209/0295-5075/2/10/003

M. Fleischhauer, A. Imamoglu, and J. P. Marangos, Electromagnetically induced transparency: Optics in coherent media, Reviews of Modern Physics, vol.77, issue.2, p.633, 2005.
DOI : 10.1103/RevModPhys.77.633

A. M. Akulshin and R. J. Mclean, Fast light in atomic media, Journal of Optics, vol.12, issue.10, p.104001, 2010.
DOI : 10.1088/2040-8978/12/10/104001

N. Sangouard, C. Simon, H. De-riedmatten, and N. Gisin, Quantum repeaters based on atomic ensembles and linear optics, Reviews of Modern Physics, vol.83, issue.1, p.33, 2011.
DOI : 10.1103/RevModPhys.83.33

N. Mercadier, W. Guerin, M. Chevrollier, and R. Kaiser, L??vy flights of photons in hot atomic vapours, Nature Physics, vol.289, issue.8, p.602, 2009.
DOI : 10.1103/PhysRevLett.73.2946

A. Fioretti, A. F. Molisch, J. H. Mutter, P. Verkerk, and M. Allegrini, Observation of radiation trapping in a dense Cs magneto-optical trap, Optics Communications, vol.149, issue.4-6, p.415, 1998.
DOI : 10.1016/S0030-4018(97)00704-9

G. Labeyrie, Slow Diffusion of Light in a Cold Atomic Cloud, Physical Review Letters, vol.91, issue.22, p.223904, 2003.
DOI : 10.1103/PhysRevLett.91.223904
URL : https://hal.archives-ouvertes.fr/hal-00023807

G. Labeyrie, Coherent Backscattering of Light by Cold Atoms, Physical Review Letters, vol.83, issue.25, p.5266, 1999.
DOI : 10.1103/PhysRevLett.83.5266
URL : https://hal.archives-ouvertes.fr/hal-00002511

Y. Bidel, Coherent Light Transport in a Cold Strontium Cloud, Physical Review Letters, vol.88, issue.20, p.203902, 2002.
DOI : 10.1103/PhysRevLett.88.203902

G. Birkl, M. Gatzke, I. H. Deutsch, S. L. Rolston, and W. D. Phillips, Bragg Scattering from Atoms in Optical Lattices, Physical Review Letters, vol.75, issue.15, p.2823, 1995.
DOI : 10.1103/PhysRevLett.75.2823

M. Weidemüller, A. Hemmerich, A. Görlitz, T. Esslinger, and T. W. Hänsch, Bragg Diffraction in an Atomic Lattice Bound by Light, Physical Review Letters, vol.75, issue.25, p.4583, 1995.
DOI : 10.1103/PhysRevLett.75.4583

A. Schilke, C. Zimmermann, P. W. Courteille, and W. Guerin, Photonic Band Gaps in One-Dimensionally Ordered Cold Atomic Vapors, Physical Review Letters, vol.106, issue.22, p.223903, 2011.
DOI : 10.1103/PhysRevLett.106.223903
URL : https://hal.archives-ouvertes.fr/hal-00557131

M. Antezza and Y. Castin, Fano-Hopfield model and photonic band gaps for an arbitrary atomic lattice, Physical Review A, vol.80, issue.1, p.13816, 2009.
DOI : 10.1103/PhysRevA.80.013816
URL : https://hal.archives-ouvertes.fr/hal-00406429

D. Yu, atomic lattice, Physical Review A, vol.84, issue.4, p.43833, 2011.
DOI : 10.1103/PhysRevA.84.043833

A. B. Matsko, I. Novikova, M. O. Scully, and G. R. Welch, Radiation Trapping in Coherent Media, Physical Review Letters, vol.87, issue.13, p.133601, 2001.
DOI : 10.1103/PhysRevLett.87.133601

V. M. Datsyuk, I. M. Sokolov, D. V. Kupriyanov, and M. D. Havey, Diffuse light scattering dynamics under conditions of electromagnetically induced transparency, Physical Review A, vol.74, issue.4, p.43812, 2006.
DOI : 10.1103/PhysRevA.74.043812

L. S. Froufe-pérez, W. Guerin, R. Carminati, R. Kaiser, and W. Guerin, Threshold of a Random Laser with Cold Atoms, Physical Review Letters, vol.102, issue.17, pp.173903-024002, 2009.
DOI : 10.1103/PhysRevLett.102.173903

D. Petrosyan, Tunable photonic band gaps with coherently driven atoms in optical lattices, Physical Review A, vol.76, issue.5, p.53823, 2007.
DOI : 10.1103/PhysRevA.76.053823

A. André and M. D. Lukin, Manipulating Light Pulses via Dynamically Controlled Photonic Band gap, Physical Review Letters, vol.89, issue.14, p.143602, 2002.
DOI : 10.1103/PhysRevLett.89.143602

M. Artoni, G. C. La-rocca, L. E. De-araujo, C. O-'brien, and O. Kocharovskaya, Optically Tunable Photonic Stop Bands in Homogeneous Absorbing Media, Physical Review Letters, vol.96, issue.7, pp.73905-137401, 2006.
DOI : 10.1103/PhysRevLett.96.073905

Y. Lin, Stationary Light Pulses in Cold Atomic Media and without Bragg Gratings, Physical Review Letters, vol.102, issue.21, p.213601, 2009.
DOI : 10.1103/PhysRevLett.102.213601

M. Born and E. Wolf, Principle of Optics, 1999.

J. Lekner, Light in periodically stratified media, Journal of the Optical Society of America A, vol.11, issue.11, p.2892, 1994.
DOI : 10.1364/JOSAA.11.002892

J. M. Bendickson, J. P. Dowling, and M. Scalora, Analytic expressions for the electromagnetic mode density in finite, one-dimensional, photonic band-gap structures, Physical Review E, vol.53, issue.4, p.4107, 1996.
DOI : 10.1103/PhysRevE.53.4107

S. Slama, Dimensional crossover in Bragg scattering from an optical lattice, Physical Review A, vol.72, issue.3, p.31402, 2005.
DOI : 10.1103/PhysRevA.72.031402

I. H. Deutsch, R. J. Spreeuw, S. L. Rolston, and W. D. Phillips, Photonic band gaps in optical lattices, Physical Review A, vol.52, issue.2, p.1394, 1995.
DOI : 10.1103/PhysRevA.52.1394

M. Artoni, G. L. Rocca, and F. Bassani, Resonantly absorbing one-dimensional photonic crystals, Physical Review E, vol.72, issue.4, p.46604, 2005.
DOI : 10.1103/PhysRevE.72.046604

S. Slama, C. Von-cube, M. Kohler, C. Zimmermann, and P. W. Courteille, Multiple reflections and diffuse scattering in Bragg scattering at optical lattices, Physical Review A, vol.73, issue.2, p.23424, 2006.
DOI : 10.1103/PhysRevA.73.023424

G. Boedecker and C. Henkel, All-frequency effective medium theory of a photonic crystal, Optics Express, vol.11, issue.13, p.1590, 2003.
DOI : 10.1364/OE.11.001590

C. Zimmermann, V. Vuletic, A. Hemmerich, L. Ricci, and T. W. Hänsch, Design for a compact tunable Ti:sapphire laser, Optics Letters, vol.20, issue.3, p.297, 1995.
DOI : 10.1364/OL.20.000297

Y. Chen, C. Lin, and I. A. Yu, Roles of degenerate Zeeman levels in electromagnetically induced transparency, Physical Review A, vol.61, issue.5, p.53805, 2000.
DOI : 10.1103/PhysRevA.61.053805

M. Yan, E. G. Rickey, and Y. Zhu, Electromagnetically induced transparency in cold rubidium atoms, Journal of the Optical Society of America B, vol.18, issue.8, p.1057, 2001.
DOI : 10.1364/JOSAB.18.001057

S. E. Harris and Y. Yamamoto, Photon Switching by Quantum Interference, Physical Review Letters, vol.81, issue.17, p.3611, 1998.
DOI : 10.1103/PhysRevLett.81.3611

M. Yan, E. G. Rickey, and Y. Zhu, Observation of absorptive photon switching by quantum interference, Physical Review A, vol.64, issue.4, p.41801, 2001.
DOI : 10.1103/PhysRevA.64.041801

H. J. Kimble, The quantum internet, Nature, vol.137, issue.7198, p.1023, 2008.
DOI : 10.1038/nature07127

D. E. Chang, A. S. Sørensen, E. A. Demler, and M. D. Lukin, A single-photon transistor using nanoscale surface plasmons, Nature Physics, vol.12, issue.11, p.807, 2007.
DOI : 10.1038/nphys708

M. Bajcsy, Efficient All-Optical Switching Using Slow Light within a Hollow Fiber, Physical Review Letters, vol.102, issue.20, p.203902, 2009.
DOI : 10.1103/PhysRevLett.102.203902

M. Albert, A. Dantan, and M. Drewsen, Cavity electromagnetically induced transparency and all-optical switching using ion Coulomb crystals, Nature Photonics, vol.5, issue.10, p.633, 2011.
DOI : 10.1103/PhysRevA.82.013807
URL : http://arxiv.org/abs/1102.5010

A. E. Nielsen and J. Kerckhoff, atom in a cavity QED system, Physical Review A, vol.84, issue.4, p.43821, 2011.
DOI : 10.1103/PhysRevA.84.043821

M. Scalora, Ultrashort pulse propagation at the photonic band edge: Large tunable group delay with minimal distortion and loss, Physical Review E, vol.54, issue.2, p.1078, 1996.
DOI : 10.1103/PhysRevE.54.R1078

F. Bariani, I. Carusotto, and J. Eur, Light propagation in atomic Mott Insulators, Journal of the European Optical Society: Rapid Publications, vol.3, p.8005, 2008.
DOI : 10.2971/jeos.2008.08005

I. Carusotto, M. Antezza, F. Bariani, S. De-liberato, and C. Ciuti, Optical properties of atomic Mott insulators: From slow light to dynamical Casimir effects, Physical Review A, vol.77, issue.6, p.63621, 2008.
DOI : 10.1103/PhysRevA.77.063621

F. Bariani and I. Carusotto, Photon wave-packet manipulation via dynamic electromagnetically induced transparency in multilayer structures, Physical Review A, vol.81, issue.1, p.13836, 2010.
DOI : 10.1103/PhysRevA.81.013836