Experimental Investigations of Time-Delay Signature Concealment in Chaotic External Cavity VCSELs Subject to Variable Optical Polarization Angle of Feedback

Time-delay signatures in multi-transverse mode VCSELs subject to double-cavity polarization-rotated optical feedback

“…The negative value indicates anticorrelation after one round trip, which originates from the anticorrelated dynamics of the X and Y polarization [34]. In previous studies [25][26][27][28][29][30][31][32][33][34], TD signatures are concealed when the peaks corresponding to the time delays are suppressed. Fig.…”

“…When the polarization of optical feedback is rotated through a large angle, temporal fluctuation occurs in the optical spectrum of both polarizations. As an example, optical spectra of the X polarization at two different times are shown in Fig Autocorrelation function (ACF) is a commonly used tool for identification of TD features [23][24][25][26][27][28][29][30][31][32]. The ACF is defined as where I is the output intensity of the VCSEL, <> denotes time average, and t is the delay time.…”

“…These features make VCSEL very useful for opticfiber communications [36]. Correspondingly, concealment of TD signatures has been extensively studied in the single-transverse-mode regime of VCSELs [28][29][30][31][33][34][35].…”

Time-delay signature of chaos in 1550 nm VCSELs with variable-polarization FBG feedback

“…Different from EELs, the output of VCSELs generally includes two orthogonally linearly polarized components (called "X-polarized component" and "Y-polarized component") due to the weak cavity and material anisotropies. The polarization nature in VCSELs results in some novel polarization-related feedback schemes proposed such as polarization-rotated optical feedback, polarization-preserved optical feedback, and variable-polarization optical feedback [14,[29][30][31][32][33]. So far, there are many reports on the TDS suppression in such polarization-related optical feedback VCSELs chaotic systems [31][32][33].…”

“…The polarization nature in VCSELs results in some novel polarization-related feedback schemes proposed such as polarization-rotated optical feedback, polarization-preserved optical feedback, and variable-polarization optical feedback [14,[29][30][31][32][33]. So far, there are many reports on the TDS suppression in such polarization-related optical feedback VCSELs chaotic systems [31][32][33]. However, these related investigations are almost always focused on the case that the optical feedback is provided by a mirror, and pay little attention on the condition that the optical feedback is provided by a FBG.…”