Research Of Four-Wave-Mixing And Dispersion Measurement Of Photonic Crystal Fiber

Because of its unique cladding structure,the novel geometry leads to the photonic crystal fibers (PCF) with remarkable optical properties, many of which are not abtainable using conventional fibers, such as the controlled dispersion characteristics, high nonlinearty and so on. The development of studies on PCF has made a significant impact on the conventional fiber optics.Recent decades, there has been growing interest in the quantum communication with the advantages of fast transmission and confidentiality.Most of quantum communication experiments are made using entangled photon pairs. To generate entangled photons in PCF can improve the large coupling loss for the correlated photons generated in nonlinear crystal and directly opplied to the existing optical fiber net. The main mechanism to generate the entangled pairs in PCF is the four-wave-mixing (FWM). Hence, it has been a attracted interest to realize an efficient photon source.Research has show that the zero dispersion wavelength of the fiber and nonlinear coefficient have evident implications of the photonic crystal fiber to generate entangled photon pairs. There are many advantages in photonic crystal fibers, such as flexibility in the design of zero dispersion wavelength and dispersion slope, highly nonlinear characteristics.These are very convenience for abtaining an efficient and bright entangled photon source. Further, the other important field to generate entangled photon sources is that measure the dispersion characteristics of PCF accurately, which is correlated with the gain speciality of the signal and idler lights by FWM. Thereby, to build a dispersion measurement system is very valuable.This thesis includes the main contents are listed as following.The first chapter gives bibliographic information for the photonic crystal fibres in general.The fabrication, propertices and applications of PCF were also represented.The second chapter describes dedailedly several experimental methods to realize entangled photon source.The features of generating correlated photon pairs in PCF with FWM process are emphasized.In the third chapter, numerical simulation is used to characterize the gain of FWM in PCF. The influences on characterizations of FWM in PCF following the controlled parameter such as the power and wavelength of input pulses, the length,zero dispersion wavelength,dispersion slope and nonlinear coefficient of the PCF are studied in detail.The basic rules to choose parameters of a PCF for the efficient and bright entangled photon source are proposed.An optimized fitering position with higher signal noise ratio is pointed for the first time to our knowledge.The fourth chapter introduces the measurement principle of the white light interferometer. A corresponding device by use of the supercontinuum generation in a fiber with femtosecond laser pulses is designed and set up. Several different styles of PCF have been characterized, which verfied the device to be an accurate dispersion measurement tool.Some of numerical results agree well with the measurement.Finally, the main results and some imperfections in this thesis are summarized.The further improvement and outlook of the investigating work are proposed.