Coherent Manipulation Of Optical Information Based On Atomic Coherence In Solid

The manipulation of light via quantum coherence and interference effects inoptical medium interacting with electromagnetic fields has been studied extensivelyboth theoretically and experimentally in solid medium. Solid-state mediums providespatially fixed interaction centers, which is free of atomic diffusion caused by themotion of the atoms in atomic gases. Moreover, Solid-state systems have theproperties of large density and scalability, and are easily integrated incommunication networks, and will be important in all optical networks andquantum computers. Drak-state polarizition based multiple optical mode andinformation transfer are investigated in this thesis.1. Light storage via slow-light four-mixing. In this part, we experimentallydemonstrate a light storage via slow-light four-wave mixing in a solid-state mediumwith a four-level double lambda scheme. Under EIT condition, the strong controlfield and weak probe field are applied to the medium, the group velocity of theweak probe field is slowed due to the change in the absorption and dispersion.whendouble control field are applied in the above process, the three level lambda schemeis transferred into four level double lambda scheme. Based on four-wave mixing,we obtain a slowed FWM signal pulse together with the slowed probe pulse. Duringthe propagation of the slowed probe pulse and newly generated FWM pulse, thesimultaneous storage and retrieval of these two slowed light pulses are studied bymanipulating the intensity of the control fields. This work experimentallydemonstrates the possibility that the dark-state polariton and stored spin coherencemay consist of two optical modes with distinct frequencies. This light storage basedon slow-light FWM consists of two optical modes, which are useful in information processing and all-optical network.2. Slow-light information conversion in a rare-earth-ion-doped solid. Weexperimentally demonstrate a controllable slow-light information conversion viaEIT in a Pr³⁺: Y₂SiO₅(Pr: YSO) crystal. The input weak classical signal pulse isfirst slowed under EIT conditions, Then the slowed pulse is partially transformedinto different frequency-spatial modes in the presence of two strong control fieldspartially overlapping in time. Some important characteristics of both initial andtransformed frequency-spatial modes are studied, such as the pulse shapes and theirenergies. We also demonstrate the storage and retrieve of both slow light pulse. Theultimate goal of this research is a controllable frequency-spatial multiplexing of thequantum state of the optical field. As a step towards this ultimate goal, we deal withan experimental investigation of the specific pulsed regime of the four-wave mixingin the four-level double-lambda configuration. Future information communicationand all-optical networks will be based on light waves.A key property of a networkis the ability to transfer (or distribute) light information between optical modes in acontrolled fashion. This is important not only for routing light information, but alsofor interfacing communication lines of different wavelengths. This slow-lightinformation conversion can be used as a controllable frequency-spatial multiplexingof the quantum state of the optical field and will be important in informationprocessing and all-optical networks.3. Controllable beating signal using stored light pulse in a solid. Weexperimentally studied a controllable beating signal using EIT-based light storagein a Pr³⁺: Y₂SiO₅(Pr: YSO) crystal. This beating signal relies on asymmetricprocedure of light storage and retrieval. Under EIT condition, the probe light pulseis firstly slowed, and then stored into the spin coherence by switching off thecontrol field. In the retrieval process, two-color control fields with oppositedetunings are used to scatter the stored spin coherence. In this case, the retrieved signals exhibit two optical components with distinct frequencies. Thus, the beatingsignal is generated due to constructive and destructive interference in the retrievedsignal intensities. The beating signal arises from the interference of two opticalcomponents in dark-state polariton. Such an interferometric beating signal can beused to monitor the frequencies and stabilities of laser fields, and find potentialapplications in precise atomic spectroscopy and fast quantum limitedmeasurements.