Optical Information Processing Based On Whispering-Gallery Cavities And Cavity Optomechanical Systems

With the advent of the information era, information processing based on the traditional electronic devices could not satisfy the increasing needs gradually. Compared with the electrons, the photons have much superiority in information processing. The development of optical information processing relies on the progress in optical devices. In recent years, the whispering-gallery-mode microcavities and cavity optomechanical systems have attracted much attention due to their simple structure and versatile features.They have great potential for optical information processing devices. In this thesis, we investigated the properties of the two kinds of systems and their applications in optical information processing. The main work are as follows:1. We build an experimental system for studying whispering-gallery-mode(WGM)microcavities. Based on the system, we can fabricate three types of WGM microcavities with the diameter ranging from 30μm to 150 μm, including microsphere, microdisk and microtoroid. The fiber taper is fabricated via pulling standard fiber heated by the hydrogen flame, and its waist diameter is 1-2 μm. By coupling with fiber taper, the cavities can be excited and measured.2. We observed and explained the dynamic Fano-like linshape in active cavities. We found that the lineshape evolves with the change of the pump power, the probe power and the scanning speed of the probe. To explain the phenomenon, we have developed a theoretical model based on coupled mode theory and laser rate equations for a three-level system, which agrees well with the experimental observations.3. We fabricated coupled microtoroid cavities with high quality factors. We also introduced a Rayleigh scatter to engineer the normal modes of the coupled system. We realized parity-time(PT) symmetric WGM microcavities by introducing gain into one of the coupled cavities. We observed the PT symmetry and its spontaneous breaking.Besides, we observed non-reciprocity in this system under certain conditions.4. We theoretically studied the optomechanical normal modes in cavity optomechanical system and their applications in quantum information processing. By engineering the normal modes, we show that it is feasible to transfer a single phonon between two mechanical modes with distinct frequencies, and an entangled W state among the three modes can be prepared.5. We theoretically studied the three-pathway electromagnetically induced transparency in coupled-cavity optomechanical system. Based on the model, we found that in addition to the three-pathway electromagnetically induced absorption as reported before,three-pathway electromagnetically induced transparency could also exist under certain conditions.