Fast and Chaotic Fiber-Based Nonlinear Polarization Scrambler

Abstract

International audienceWe report a simple and efficient all-optical polarization scrambler based on the nonlinear interaction in an optical fiber between a signal beam and its backward replica which is generated and amplified by a reflective loop. When the amplification factor exceeds a certain threshold, the system exhibits a chaotic regime in which the evolution of the output polarization state of the signal becomes temporally chaotic and scrambled all over the surface of the Poincaré sphere. We numerically derive some design rules for the scrambling performances of our device which are well confirmed by the experimental results. The polarization scrambler has been successfully tested on a 10-Gbit/s On/Off Keying Telecom signal, reaching scrambling speeds up to 500-krad/s, as well as in a wavelength division multiplexing configuration. A different configuration based on a following cascade of polarization scramblers is also discussed numerically, which leads to an increase of the scrambling performances

All-Optical Signal Processing Based on Self-Induced Polarization Control in Optical Fibers

“…In this section we discuss the third regime of operation of the Omnipolarizer, which allows implementing an all-optical fully chaotic polarization scrambler. Indeed, as underlined in Sections II and III, for a large power imbalance between the forward beam and its backward replica, the system exhibits a genuine chaotic dynamics so that even a well-polarized incident signal becomes scrambled all over the Poincaré sphere at the fiber output [64][65][66][67][68][69].…”

“…Two threshold values of the reflection coefficient ρ are found that characterize this chaotic dynamics, which are ρA=9π / (16•L•Ps,out•) and ρC≃5ρA, being Ps,out the power of the forward signal at the fiber exit. If ρ is below the threshold ρA then the system exhibits stationary states that are stable, therefore a signal which is fully polarized in input (DOP=1) turns out to be still polarized in output with an SOP that strictly depend on the system parameters and on the input SOP [69]. On the other hand when ρ>ρC the stationary states don't exhibit anymore a monotonic evolution along the fiber length and thus, start to oscillate and become unstable.…”

“…[72]. For intermediate values ρA≤ρ≤ρC the output signal undergoes a complex dynamics: depending on its input polarization and on the rotation R, it may be fully polarized or scrambled or even exhibit a periodic temporal trajectory [69].…”

“…In this phenomenon of self-induced polarization attraction, the signal beam interacts with its own counter-propagating replica, which is generated at the fiber end by means of a reflected element, e.g., fiber Bragg-mirror, or amplified reflective fiber loop [56][57][58]. Furthermore, it has been shown that the Omnipolarizer may exhibit a chaotic polarization dynamics which could induce a fast and efficient polarization scrambling [64][65][66][67][68][69][70]. Both the attraction and the chaotic processes are two different aspects of the all-optical and selfinduced polarization control which takes place within the Omnipolarizer.…”

[INVITED] Self-induced polarization tracking, tunneling effect and modal attraction in optical fiber

“…Finally, for larger reflection coefficients, i.e., ρ >>1, a chaotic dynamics can be reached, leading to an all-optical scrambling of the output polarization [70], which is briefly introduced in next section and discussed in more details elsewhere [71].…”