A reservoir computing (RC) system based on a semiconductor laser (SL) with double optical feedback and optical injection is proposed, and the prediction performance of such a system is numerically investigated via Santa Fe Time-Series Prediction task. The simulation results indicate that the RC system can yield a good prediction performance. Through optimizing some relevant operating parameters, ultra-fast information processing rates up to Gb/s level can be realized for the prediction error is below 3%.

We numerically investigate the nonlinear dynamic properties of an exclusive excited-state (ES) emission quantum dot (QD) laser under optical injection. The results show that, under suitable injection parameters, the ES-QD laser can exhibit rich nonlinear dynamical behaviors, such as injection locking (IL), period one (P1), period two (P2), multi-period (MP), and chaotic pulsation (CP). Through mapping these dynamic states in the parameter space of the frequency detuning and the injection coefficient, it can be found that the IL occupies a wide region and the dynamic evolution routes appear in multiple forms. Via permutation entropy (PE) calculation to quantify the complexity of the CP state, the parameter range for acquiring the chaos with high complexity can be determined. Moreover, the influence of the linewidth enhancement factor (LEF) on the dynamical state of the ES-QD laser is analyzed. With the increase of the LEF value, the chaotic area shrinks (expands) in the negative (positive) frequency detuning region, and the IL region gradually shifts towards the negative frequency detuning.

In this work, we propose and numerically investigate a scheme for reservoir computing (RC) based on two parallel reservoirs under identical electrical message injection, in which two semiconductor lasers (SLs) under optical feedback are utilized as two parallel reservoirs. For simplifying the system, only one mask signal is employed in this scheme. After multiplying with input data, the masked information is injected into two parallel reservoir lasers (SL1 and SL2). The virtual node states can be obtained from the temporal outputs of two SLs. RC can be accomplished by three ways, namely RC1/RC2 (the virtual node states originating from SL1/SL2 are used for training and testing) and RCM (the merged virtual node states originating from two SLs are used for training and testing). Via chaotic time series prediction task and memory capacity (MC) test, the performance of the RC system is simulated and assessed. The results show that, for a given data processing rate, better prediction performance and higher MC can be realized by RCM through setting suitable mismatched parameters between the two SLs. Under satisfying the requirement for achieving a good performance, the highest data processing rate can be doubled for RCM with respect to that for RC1/RC2.

A simple scheme for generating chaotic signals with concealed time-delay signature (TDS) is proposed and experimentally demonstrated. The architecture of the system is based on a semiconductor laser (SL) under multi-path optical feedback (MPOF) provided by a 2 × 2 fiber coupler (FC) and a fiber mirror (FM). The results show that SLs with MPOF are more beneficial for achieving TDS suppressed chaotic output than those with single optical feedback (SOF) systems. In addition, the TDS of the chaotic signal generated by the SL under MPOF is insensitive to the length deviation of the feedback cavities, and therefore such a scheme is convenient for practical application. Furthermore, the influence of FC coupling ratio in the MPOF module, feedback strength, and bias current of the SL on the TDS is comprehensively studied. By selecting suitable parameters, the TDS of the chaotic signal generated by the SL under MPOF can be completely concealed. Finally, permutation entropy (PE) is adopted to evaluate the complexity of the generated chaotic signal, and the result demonstrates that the suppression of TDS does not lead to the degradation of complexity for the proposed scheme. Index Terms-Chaos, multi-path optical feedback (MPOF), semiconductor laser (SL), time-delay signature (TDS). I. INTRODUCTIONO PTICAL chaotic sources based on semiconductor lasers (SLs) under various external perturbations such as optical feedback [1]-[7], optical injection [8]- [11], and optoelectronic feedback [12], have received great attention because of their important applications in secure communication [13], random bits generation [14], [15], optical sensors [16], range radar [17], etc. Among these chaotic sources, external cavity semiconductor lasers (ECSLs) attract extra concern because of their abundant dynamic characteristics and compatibility with optical communication systems [18]. However, the chaotic signal from an Manuscript