Time-delay signature concealment of polarizationresolved chaos outputs in vertical-cavity surface-emitting lasers with variable-polarization filtered optical feedback

Through employing permutation entropy and the self-correlation function, the time-delay signature(TDS) of a vertical-cavity surface-emitting laser(VCSEL) with variable-polarization filtered optical feedback(VPFOF) is evaluated theoretically. The work shows that the feedback rate η, polarizer angle θp, and filter bandwidth Λ have an obvious influence on the TDS. The evolution maps of the TDS in parameter spaceeη; ΛT and eη; θpT are simulated for searching the chaos with weak TDS. Furthermore, compared with a VCSEL with polarization-preserved filtered optical feedback and a VCSEL with variable-polarization mirror optical feedback, this VPFOF–VCSEL shows superiority in TDS suppression.