The Parametric Oscillator Of The Spatial High Order Modes Of Femtosecond Pulse Light

Non-classical light, such as the squeezed state, entangled state and so on, generated by the optical parametric oscillator is very important in the quantum information science. It is an essential source in quantum network construction, which has an extensive application in the quantum communication, quantum storage and quantum imaging. Multiple spatial modes with more complex spatial structure and more information can allow parallel transfer of quantum information through an optical network and also provide advantages in regard to the complexity of quantum information protocols. It is well know that the femtosecond mode-locked laser has a narrow pulse width, high repetition rate and constant phase between the adjacent longitudinal modes, so its peak power is 105-106 times than the continuous light. With above advantages, it has been seen as a popular coherent source. In addition, femtosecond pulse light has a broad spectrum at the nanometer level, and through the Fourier transform it can be expanded into thousands of frequency modes (named as frequency combs) which is promising to be applied in the time transmission and precision measurement.The main works of this thesis are around the parametric oscillator of the spatial high order Hermite-Gaussian modes for the femtosecond pulse light. The key parts of the thesis include the following contents:1) The realization of the amplitude squeezed state and the quadrature phase squeezed state of the spatial TEM00 mode for the femtosecond pulse light. The synchronously pumped optical parametric oscillator is an important optical device for the ultra-short pulse light to generate parametric oscillator. The device not only keeps the structure of the frequency combs but also amplifies the intensity of the incident field by generating resonance in the linear cavity. The type-I PPKTP crystal in the singly resonant linear cavity pumped by the fundamental mode pump light, we generate the 2.5 dB amplitude squeezed state and 2.58 dB quadrature phase squeezed state in the experiment.2) The classical gain generation of the spatial TEM01 Hermite-Gaussian mode for the femtosecond pulse light in the experiment. In the first, we introduce a small modulations, such as a small displacement and tilt,in the fundamental mode of the center wavelength being 850nm, which can generate the spatial TEM01 mode. And then, the type-I PPKTP crystal in the synchronously pumped optical parametric oscillator pumped by the fundamental mode pump light of the center wavelength being 45nm, we can generate about 4 times classical gain through the parametric down-conversion in the singly resonant linear cavity. The gain that we get in the experiment is consistent with the theoretical inference on the whole. For the spatial TEM01 mode of the femtosecond pulse light, the realization of the classical gain in our experiment is important for our next plan to generate the squeezed state of the high order mode of the ultra-short pulse light. With the gain that we have got in the experiment, we can generate about 2.20 dB quadrature phase squeezed state through the theoretical inference.