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%.

Using two mutually coupled semiconductor lasers (MC-SLs) outputs as chaotic entropy sources, a scheme for generating Tbits/s ultra-fast physical random bit (PRB) is demonstrated and analyzed experimentally. Firstly, two entropy sources originating from two chaotic outputs of MC-SLs are obtained in parallel. Secondly, by adopting multiple optimized post-processing methods, two PRB streams with the generation rate of 0.56 Tbits/s are extracted from the two entropy sources and their randomness are verified by using NIST Special Publication 800-22 statistical tests. Through merging the two sets of 0.56 Tbits/s PRB streams by an interleaving operation, a third set of 1.12 Tbits/s PRB stream, which meets all the quality criteria of NIST statistical tests, can be further acquired. Finally, after additionally taking into account the restriction of the min-entropy, the generation rate of two sets of PRB stream from the two entropy sources can still attain 0.48 Tbits/s, and then a third set of merging PRB stream is 0.96 Tbits/s. Moreover, for the sequence length of the order of 10 Gbits, the statistical bias and serial correlation coefficient of three sets of PRB streams are also analyzed.

A novel dual-channel chaotic synchronization configuration is proposed. This system is constructed on the basis of two unidirectionally coupled vertical-cavity surface-emitting lasers (VCSELs), where a VCSEL subjected to polarization-rotated optical feedback is used as a transmitter and the other VCSEL subjected to polarization-rotated optical injection is used as a receiver. The synchronization and communication performances of such a system are numerically investigated. The results show that, similar to polarization-preserved coupled system with polarization-preserved optical feedback at the T-VCSEL port and polarization-preserved optical injection at the R-VCSEL port, such polarization-rotated coupled system can also realize complete synchronization between each pair of linear polarization (LP) modes and the total output of T-VCSEL and R-VCSEL. Compared with the polarization-preserved coupled system, this proposed system has higher tolerance to mismatched parameters. Furthermore, the average intensities of two orthogonal LP modes are almost the same so that this framework may be used to realize dual-channel chaos communication. Under the additive chaos modulation (ACM) encryption scheme, the encoded messages can be successfully extracted for both of orthogonal LP modes.

In this paper, evolution of time delay (TD) signature of chaos generated in a mutual delay-coupled semiconductor lasers (MDC-SLs) system is investigated experimentally and theoretically. Two statistical methods, including self-correlation function (SF) and permutation entropy (PE), are used to estimate the TD signature of chaotic time series. Through extracting the characteristic peak from the SF curve, a series of TD signature evolution maps are firstly obtained in the parameter space of coupled strength and frequency detuning. Meantime, the influences of injection current on the evolution maps of TD signature have been discussed, and the optimum scope of TD signature suppression is also specified. An overall qualitative agreement between our theoretical and experimental results is obtained.

Based on an optically injected semiconductor laser (OISL) operating at period-one (P1) nonlinear dynamical state, high-purity millimeter-wave generation at 60 GHz band is experimentally demonstrated via 1/4 and 1/9 subharmonic microwave modulation (the order of subharmonic is with respect to the frequency f_c of the acquired 60 GHz band millimeter-wave but not the fundamental frequency f₀ of P1 oscillation). Optical injection is firstly used to drive a semiconductor laser into P1 state. For the OISL operates at P1 state with a fundamental frequency f₀ = 49.43 GHz, by introducing 1/4 subharmonic modulation with a modulation frequency of f_m = 15.32 GHz, a 60 GHz band millimeter-wave with central frequency f_c = 61.28 GHz ( = 4f_m) is experimentally generated, whose linewidth is below 1.6 kHz and SSB phase noise at offset frequency 10 kHz is about −96 dBc/Hz. For f_m is varied between 13.58 GHz and 16.49 GHz, f_c can be tuned from 54.32 GHz to 65.96 GHz under matched modulation power P_m. Moreover, for the OISL operates at P1 state with f₀ = 45.02 GHz, a higher order subharmonic modulation (1/9) is introduced into the OISL for obtaining high-purity 60 GHz band microwave signal. With (f_m, P_m) = (7.23 GHz, 13.00 dBm), a microwave signal at 65.07 GHz ( = 9f_m) with a linewidth below 1.6 kHz and a SSB phase noise less than −98 dBc/Hz is experimentally generated. Also, the central frequency f_c can be tuned in a certain range through adjusting f_m and selecting matched P_m.

The time-delay signature (TDS) of chaos output in a 1550 nm vertical-cavity surface-emitting laser (VCSEL) subject to fiber Bragg grating (FBG) feedback is investigated experimentally. Autocorrelation function (ACF) and mutual information (MI) are used for quantitatively identifying the TDS of chaos. For various bias currents, the TDS evolution with the feedback strength is different, as the FBG provides wavelength-selective feedback. Furthermore, based on the TDS map of the FBG feedback VCSEL (FBGF-VCSEL) in the parameter space of feedback strength and bias current, the optimal TDS suppression regions, where the dominant polarization mode of FBGF-VCSEL locates at the edge of the main lobe of FBG reflection spectrum, have been determined. Finally, for comparative purpose, the TDS of chaos in mirror feedback VCSEL (MF-VCSEL) also has been presented, and the results show that an FBGF-VCSEL possesses better TDS suppression performance than an MF-VCSEL.