Research On Polarization Effect In Fiber Optical Parametric Amplifier And The Application Of Spun Fiber

Fiber-optic parametric amplifiers (FOPA) have many kinds of applications in lightwave systems such as optical amplification, wavelength conversion and phase conjugation. FOPA can achieve high and flat gain spectrum over a wide wavelength range (>100nm). Besides, FOPA add relatively less noise to signal than the other kinds of optical amplifiers, in an extreme example, a phase-sensitive FOPA can get OdB noise figure. However, FOPA doesn’t perform so perfect as it should be in reality, there are several reasons that limit the performance of FOPA, and this thesis focus on the polarization state effect.Fiber optic parametric amplifier often exhibits polarization-dependent gain and its noise characteristics are also polarization-dependent. Noise figure for several basic types of states of polarization (SOPs) in FOPA is theoretically analyzed and simulated. It is proved that noise changes significantly with the type of SOPs and varies with the relationship between SOP of pumps and signal, either co-polarized or orthogonally polarized. Two noises namely quantum noise under different SOP conditions and Raman induced noise as a function of elliptical angle are analyzed separately. The possible reasons for the polarization dependent noise are discussed.The efficiency of FOPA suffers from The imperfect of ordinary single mode fiber, and twist it during the drawing procedure can influence the linear birefringence that exists in any real fiber due to deviations from a circular shape of its core or due to internal stress, and it is called spun fiber. It is proved in this thesis that birefringence in the spun fiber is reduce by the twist to almost0, thus, it can be regard as the perfect isotropic fiber. Its application in FOPA is also discussed in the thesis.