Bragg amplification and oscillation in periodic optical media

Hossam Zoweil, John W. Y. Lit

Власов Антон Юрьевич

Igor V. Mel’nikov, C. M. Bowden, Michael Scalora +1 more

Summary form only given. In recent years, there has been considerable interest in nonlinear and quantum optics of photonic bandgap structures. Some of this attention has centered on the properties of gap solitary waves, which are light pulses tuned at a Bragg frequency within a forbidden bandgap of the periodic structure. These solitary waves may occur in a periodically modulated medium with a Kerr-like nonlinearity, and in the resonance grating as a two-wave soliton of self-induced transparency. In the later case, the coupled-mode Maxwell-Bloch equations which describe the on-resonance coherent interaction of the intense field with a periodic structure of thin layers of two-level atoms in the ground state, lead to an integrable sine-Gordon equation. In our study, we concentrate on the nonintegrable case, that is, amplification in a resonant Bragg structure by means of a comprehensive analysis that includes and numerical modelling of Dicke superradiance and coherent amplification.

Shiva Kumar, G. V. Anand, A. Selvarajan

Bo Lü, Thibault Vogt, Xinxing Liu +3 more

Correlations of a Bose gas released from an optical lattice are measured using superradiant scattering. Conditions are chosen so that, after initial incident light pumping at the Bragg angle for diffraction, superradiant scattering into the Bragg diffracted mode is preponderant due to matter-wave amplification and mode competition. A temporal analysis of the superradiant scattering gain reveals periodical oscillations and damping due to the initial lack of coherence between lattice sites. Such damping is used for characterizing first-order spatial correlations in our system with a precision of one lattice period.

Xiaojun Zhang, Hai-Hua Wang, Lei Wang +1 more

We theoretically study the optically tunable gratings based on a L-type atomic medium using coherent population oscillations from the angle of reflection and transmission of the probe field. Adopting a standing-wave driving field, the refractive index of the medium as well as the absorption are periodically modified. Consequently, the Bragg scattering causes the effective reflection. We show that different intensities of the control field lead to three types of reflection profile which actually correspond to different absorption/amplification features of the medium. We present a detailed analyses about the influence of amplification on the reflection profile as well. The coherent population oscillation is robust to the dephasing effect, and such induced gratings could have promising applications in nonlinear optics and all-optical information processing.