Photonic band gap induced in an atomic ensemble confined inside a hollow-core optical fiber

We implement a dynamically controlled photonic bandgap \footnote{A. Andre et al., Phys. Rev. Lett. 89, 143602 (2002)} in an ensemble of laser cooled cesium atoms confined inside a hollow-core photonic crystal fiber (HCPCF). This photonic bandgap is induced in the ensemble by combining electromagnetically induced transparency (EIT) conditions with an off-resonant standing light wave, which in turn produces a rapid spatial modulation of the index of refraction experienced by the probe light. We investigate the formation of stationary light pulses through dynamic control of this bandgap.