Nonlinear Propagation of Partially Polarized Light in Optical Waveguides

One of the main differences between natural light and coherent laser radiation is that natural light is polarized only partially, i.e. it contains a component whose polarization state changes randomly in a time domain, while coherent radiation has a fixed polarized state. Traditionally nonlinear optics deals with polarized light. However during the last few years it has been found that intense laser light with chaotic polarization behaviour may be generated via the non-linear interaction of two coherent polarized light waves in a nonlinear medium [1]. This opportunity to create intense unpolarized light raises the problem of developing nonlinear optics with unpolarized and partially polarized light. In linear optics it is known that unpolarized light may change its degree of polarization as the result of an interaction with an absorbing material, polaroid film, for example. In nonlinear optics the evolution of the degree of polarization is evidently more complicated. Here we intend to address this problem considering self-action phenomena. The approach developed below may be used for consideration of the light polarization stability in optical waveguides and for treatment of the optical communication lines using polarization codding of information.