Nondegenerate Four-wave Mixing In The Diamond Configuration In Cesium Vapor

Four-wave mixing(FWM),known as an important nonlinear optical effect,has attracted much attention due to its wide applications in phase conjugation,optical parametric amplification,squeezed light generation,and optical frequency conversion.Extensive studies on quantum coherence en-hanced FWM in atomic ensembles have shown great potential to develop quantum entanglement,optical storage and quantum memory.Such quantum resources and technologies hold the promise in quantum information processing,quantum communication and networks.Compared to the nonlinear-crystal based quantum light resources via spontaneous parametric down-conversion(SPDC)or optical parametric oscillator(OPO),the quantum light generated from FWM in atoms has the frequency with narrow bandwidth matching exactly the atomic transitions.In addition,the nondegenerate FWM(NFWM)in a diamond atomic structure can produce entangled photon pairs or correlated light beams with substantially different wavelengths,which corresponds to the frequencies of different atomic transitions,or corresponds to a telecom window and an atomic transition line simultaneously.Such resources can therefore be used to realize atom-based long-distance quantum communication protocols.Most of the experimental investigations of NFWM with diamond-type atomic system were realized in cold and warm alkali atoms,generating the infrared(IR)lasers at the wavelengths dif-ferent from the pump lasers.Also,the generation of blue or ultraviolet(UV)lasers in this atomic system can be obtained.Although both of the IR and blue(or UV)lasing productions are frequency up-conversion FWM processes,the underlying physics is very complex to be clearly understood and identified.This can be possibly attributed to the fact that the coherent IR light is obtained due to seeded NFWM,whereas the blue or UV coherent emission is resulted from spontaneous NFWM.Recently,the generation of coherent mid-infrared(mid-IR)light was experimentally demonstrated with the related spontaneous frequency down-conversion NFWM in a diamond-type Rb atoms,and it was achieved mainly due to the amplified spontaneous emission(ASE),which in turn strengthen the spontaneous NFWM process being recognized as a self-seeded NFWM.The earlier studies of ASE and FWM in cascade three-level atoms excited by a pulsed laser also showed that ASE was suppressed by FWM that causes the other excitation pathway.In fact the multichannel excitations and decays involved in NFWM processes of atoms show the potential in exploring more nonlinear effects,such as heralded narrowband color-entanglement and polychromatic mirrorless lasing in cesium atoms.The first chapter is the introduction.It presents some coherent process in the interaction be-tween light and atoms and the absorption and dispersion property of the two-level system and A-type EIT system are analyzed by semi-classical theory;In the second chapter,we demonstrated generate blue laser by nondegenerate four-wave mixing in cesium vapor.In the second chapter,we present an experimental study of multichannel involved NFWMs in Cs vapor,exploiting the mix of a seeded NF WM and ASE induced self-seeded NFWM.The dependence of single-photon and two-photon detunings on the two different NFWMs is systematically studied to help us better understanding the interplay and competition between the two different processes.