Correlated Photon Pair Generation In Silicon Wire Waveguides

Thanks to high third-order nonlinear coefficient, narrow Ramanscattering spectrum and on-chip integrated fabrication process of silicon wirewaveguides, the generation of correlated photon pair in telecommunicationband utilizing silicon wire waveguides is one of the hot topics in quantuminformation science and technology. Aiming at the urgent demand oftelecommunication band quantum light source and supported by the NationalBasic Research Program (973program) project of China (“Quantum lightsource for quantum network”), correlated photon pair generation in siliconwire waveguides is investigated theoretically and experimentally in thisdissertation.The theoretical analysis of correlated photon pair generation in siliconwire waveguides is taken. Structural waveguide design and basic opticalcharacteristic analysis of silicon wire waveguides for this application aretaken by investigating their single mode condition, nonlinear coefficient,dispersion curve and group birefringence. Then the quantum perturbationtheory of spontaneous four-wave mixing is applied to silicon wire waveguides.The photon pair generation rates and spectra are investigated in both scalarand vector spontaneous four-wave mixing processes. Based on the spectrumcharacteristics of the two processes, a novel scheme of polarization-entangledphoton pair generation in silicon wire waveguides is proposed theoretically.Combined with the sub-micron semiconductor fabrication technology,the fabrication process of silicon wire waveguides is explored. Transmissionloss and coupling loss of silicon wire waveguides are investigatedtheoretically and measured experimentally, which are optimized with thethermal oxidation method to reduce the transmission loss and inverse-taperstructure to reduce the coupling loss, respectively. The silicon wire waveguidewith an insertion loss of10dB is fabricated. Pedestal supported waveguide isproposed and fabricated during the fabrication, and its characteristics of single polarization transmission are demonstrated theoretically andexperimentally, showing its potential in the application of integratedwaveguide polarizer.Correlated photon pair generation in silicon wire waveguides isdemonstrated experimentally. The experimental system for the measurementof correlated photon pairs in silicon wire waveguides is built. The quantumcorrelated feature of generated photons is demonstrated in the silicon wirewaveguide of1.6mm in length. The ratio between coincidence counts andaccidental coincidence counts is larger than19in room temperature, showingits advantage of low noise during the photon pair generation process. Theexperimental result shows that the generation rate of photon pairs stronglydepends on the polarization direction of pump light. This experiment showsthe feasibility of polarization-entangled photon pair generation in silicon wirewaveguides.