Theoretical And Experimental Investigation On The Generation Of Squeezing Light Using Optical Parametric Process In PPKTP Crystal

Since non-classical state were generated in Lab, it has been used in the various fields: precise measurement below Shot Noise Limit, quantum nondemolition measurement, andquantum information-----quantum teleportation, quantum dense coding, and quantum secretcommunication, and so on. At present, optical parametric process is the best and the most developed technology generating the non-classical state in all methods. With the coming ends of principle experiments on quantum communication, it becomes important that the experimental set-ups were maked to be practical and simple. Quasi-phase matching(QPM) is a technology that were invented to meet phase matching condition in the parametric process and were rapidly developed in last a few years. Virtually any wavelengths in the transparency regions of nonlinear material can be realized in the parametric interaction if the material can be quasi-phase matched. In addition QPM gives the possibility to utilize the largest nonlinear tensor element of the material and allows walk-off free interactions between the waves. QPM has been used to generated entanglement source in quantum information with the discrete variables, but few experiments were reported in continuous variable field. The major reason is the low squeezed degree using QPM. Our destination is to do some research on the continuous variables entanglement. During my PhD period, the following work was completed: the intensity noise of all-solid-state laser was suppressed by the amplitude modulation technology using Electric-Optical Modulator, the amplitude quadrature squeezing was generated by optical parametric de-amplification in Periodically Poled KTP(PPKTP) crystal, and the similar EIT phenomenon in optical parametric process was investigated.Following three parts will be presented in this thesis:1 The intensity noises of all-solid-state laser are suppressed by electric-optical modulator loop. The theory of the feed-forward and feed-back loop are presented and we concluded that both loops can reduce classical noise greatly in the low-frequency ranges except for the resonant relaxation oscillation peak and the feed-forward loop needs less gain to get the largest suppression is better than the feed-back loop. In experiment, the intensity noises of single-frequency ring-cavity 1064nm Nd:YVO₄ laser are reduced about 15dB and the lower is the frequency, the larger is the suppression. The Laser Diode driven-current feed-back loop can effectively suppress the resonant relaxation oscillation noise. Combined the electric-optical modulator loop and Laser Diode feed-back loop, the suppressed noise are experimentally presented and the whole noise spectrum are close to the Shot Noise Limt...