The Polarization State Of All-fiber Mzi Contrast

The all-fiber filters base on MZIs used to applied as MUX/DEMUX in DWDM system. In the last few years a novel wavelength interleving filter (interleaver) has been brought forward to attain the system with channel spacing no more than 50 GHz. It take MZIs in the foreground for it's sinusoid spectral response.With a instable polarization mode in the arms, classical MZIs has a low contrast, and it was easy influenced with temperature, stress, quiver, et al. It take a difficulty to use.In this paper, author analyzes the result of polarization mode alter by fiber birefringence, polarization-mode Coupling, Polarization sensitivity of coupler, we discuss the characteristic of output power spectrum of MZIs, research the influence of MZI output contrast caused by the states of polarization in the arms of MZIs from the aspect of theory and experiment. And brings forward the technology to get a fine and stable spectrum of MZIs. Through a great many of experiment, two different way have been get. It can influence the polarization mode of the arms of MZIs, and get the results expected.lastly, the author analyzes the effect of the bandwidth of the source in measure of MZI transmission characteristic using demodulation mode. The bandwidth ensure the precision of measure. It offer the direction of executing MZI used in experiment.It include four aspect in experiment: the effect of output contrast caused by input polarization mode in all fiber MZI; the effect of output contrast caused by turning of polarization plane; variety of output contrast caused by balance pressed at the arms; the output spectrum of MZI effect by source band.It indicates by the experiment that it can improve the capability of the all fiber MZIs that depends on the coherence of the polarization mode in the arms, It makes it easy to made a all fiber MZI with high characteristic.