Experimental Generation Of Transverse Multimode Squeezed Fields

Quantum optics, based on the quantum theory, mainly research the quantum characters of the optical field and the quantum effect of the interaction between light and matter. More than a century ago, people began to study the theory of quantum optics, which separately explained blackbody radiation and photoelectric effect. People put forward the quantum theory of radiation, quantum theory of light, which make a strong foundation for the emergence of laser. As typical coherent beam, laser provides a new future for the development of quantum optics experiment. So far, whether the theoretical or the experimental research, quantum optics has remarkable performance and nice prospect, especially in the field of the generation and application of nonclassical field.In this thesis, we introduce our works mainly around the experimental generation of transverse multimode squeezed fields. The key parts contain following aspects:(1) Noise suppression of fiber laser. As a new laser source, fiber laser has many advantages, for example: small, narrow-linewidth, stable-operation and so on. However, commercial single frequency fiber laser has large intensity noise, which limits the widely use in the field of quantum information. In the experiment, we use a self-making mode cleaner to suppress its intensity noise, which can be suppressed near to the shot noise limit after3MHz. This value is enough to meet the experiment demand.(2)The question about the resonance of high order modes in optical parametric oscillator. The oscillation of first-order Hermite-Gauss TEM01and TEM10modes in an optical parametric amplifier was analyzed theoretically. In the experiment, corresponding phenomenon was directly observed. Because of the astigmatism caused by the crystal birefringence, and TEM10modes can not resonate simultaneously in the optical parametric amplifier, which can be solved by a new and easier-to-manipulated method. Through this method, a single resonance peak was obtained for the TEM01and TEM10modes in the optical parametric amplifier.(3) Squeezed fields in high order modes. The system was seeded with a TEM01field and was carefully aligned such that the TEM01and TEM10modes can resonate simultaneously. The system can get a gain of3with green pumping in the TEMoo mode. The output fields should have squeezed character. Using balance homodyne detection with about96%interference degree, about2.8dB amplitude squeezed field in the TEM01bright mode and1.6dB amplitude squeezed field in the TEM10vacuum mode were produced separately.