All-optical polarization scrambler based on polarization beam splitting with amplified fiber ring
Optical-fiber-based polarization scramblers can reduce the impact of polarization sensitive performance of various optical fiber systems. Here, we propose a simple and efficient polarization scrambler based on an all optical Mach-Zehnder structure by combining polarization beam splitter and amplified fiber ring. To totally decoherence one polarization splitted beam, a fiber ring together with an amplifier are incorporated. The ratio of two orthogonal beams can be controlled by varying the amplification factor, and we observe different evolution trajectories of the output state of polarizations on Poincare sphere. When the amplification factor exceeds a certain threshold, the scrambler system exhibits chaotical behavior. A commercial single wavelength laser with linewidth of 3 MHz is utilized to characterize the scrambling performance. We found that when the sampling rate is 1.6 MSa/s, a scrambling speed up to 2000 krad/s can be obtained for the average degree of polarization being less than 0.1. We also exploit these chaotic polarization fluctuations to generate random binary number, indicating that the proposed technique is a good candidate for random bit generator.