Synchronization Of Semiconductor Lasers Research Articles

Physical-layer key distribution using synchronous complex dynamics of DBR semiconductor lasers

Common-signal-induced synchronization of semiconductor lasers with optical feedback inspired a promising physical-layer key distribution with information-theoretic security and potential in high rate. A significant challenge is the requirement to shorten the synchronization recovery time for increasing the key rate without sacrificing the operation parameter space for security. Here, open-loop synchronization of wavelength-tunable multi-section distributed Bragg reflector lasers is proposed as a solution for physical-layer key distribution. Experiments show that the synchronization is sensitive to two operation parameters, i.e., currents of grating section and phase section. Furthermore, fast wavelength-shift keying synchronization can be achieved by direct modulation on one of the two currents. The synchronization recovery time is shortened by one order of magnitude compared to close-loop synchronization. An experimental implementation is demonstrated with a final key rate of 5.98 Mbit/s over 160 km optical fiber distance. It is thus believed that fast-tunable multi-section semiconductor lasers open a new avenue for a high-rate physical-layer key distribution using laser synchronization.

Isochronous synchronization induced by topological heterogeneity in semiconductor laser networks

Previous work in the synchronization of semiconductor lasers (SLs) have suggest that networks with symmetric topology and homogenous parameters will be more likely to achieve synchronous states. In this work, we realize a counter-intuitive effect in SL network and show that topological heterogeneity could definitely facilitate the isochronous synchronization rather than impair that of SL networks, compared to symmetric network topology. Each SL of symmetric network is decomposed into 2 sub-nodes and the heterogeneity of network topology can be defined by the internal connection between subnodes. The influences of crucial parameters in heterogeneous SL networks on the stability of isochronous synchronization are systematically evaluated. We also calculate the maximum Lyapunov exponent of SL output to reveal the parameter space for isochronous synchronization with chaotic dynamics. Additionally, the generality of heterogeneity induced synchronization is validated for a network with different types of coupling links and topological heterogeneity. As the heterogeneity is ubiquitous in real world network topology, our results suggest a new mechanism for the topological control of synchronization in complex SL networks.

Effect of Detuning on Synchronization of Semiconductor Lasers

A simulation of chaos-synchronization of unidirectionally open-loop master-slave configuration semiconductor lasers is introduced. We consider three scenarios, both lasers are single-mode, multi-mode lasers, with three modes where the interaction is between each mode of transmitter with the corresponding mode of the receiver, and the third scenario is for 5 modes. The simulation was focused on the influences of frequency-detuning of different values of coupling strength for two types of synchronization, anticipating synchronization (AS) and isochronous synchronization (IS). The simulation results demonstrate that scenarios are sensitive to the frequency-detuning between transmitter’s and receiver’s lasers. So, the suitable increasing of coupling strength is a necessary solution to decrease the frequency-detuning effect and saving synchronization with significantly broad high-quality, which means excellent feasibility.

Synchronization of semiconductor lasers by injection of common broadband random light

Synchronization of semiconductor lasers by injection of common broadband random light

共通ランダム位相変調光による半導体レーザーの同期

共通ランダム位相変調光による半導体レーザーの同期

Chaos synchronization in semiconductor lasers with polarization-rotated optical feedback

Chaotic oscillations of the transverse magnetic (TM) mode, which is not a common lasing mode, are excited by using polarization-rotated optical feedback from the transverse electric (TE) mode in a semiconductor laser. In our previous paper, we found that the dynamics were strongly dependent on their RF components under the condition of moderate optical feedback from the TE mode to the TM mode and that they were divided into three RF regions; low-pass filtered signals with a lower frequency than the laser relaxation oscillation frequency, intermediate RF components including the relaxation oscillation frequency, and high-pass filtered signals with a higher frequency higher than the relaxation oscillation frequency. Depending on the frequency bands, the laser outputs showed different correlations. In the present study, using such schemes, the polarization-rotated beam from a transmitter laser (i.e., the rotated TE-mode beam of a transmitter laser) is injected into a receiver laser. We experimentally observe chaos synchronization in accordance with the dynamics of RF components on the transmitter laser side. We also perform numerical calculations using a model and obtain good agreement between the theoretical and experimental results.

Synchronization of semiconductor lasers with coexisting attractors

We study synchronization of unidirectionally coupled optical bistable systems. In particular, we consider two semiconductor lasers with an external cavity, which exhibit, when isolated, coexistence of two different attractors: fixed point and chaos, fixed point and one periodic orbit, and two periodic orbits with different periods. The analysis is performed with a cross-correlation function between the master and slave laser oscillations calculated with model equations based on the Lang-Kobayashi approach. Depending on both the laser operating point and the coupling strength, different bifurcations (Hopf, period doubling, saddle node, torus, and crisis) and diverse dynamical regimes (steady state, periodicity, quasiperiodicity, bistability, and chaos) occur in the route from asynchronous motion to complete synchronization. We show some similarities and differences between synchronization of monostable and bistable lasers.

Open loop synchronization of semiconductor lasers with periodical injection

In this paper, the influence of fluctuation amplitude and frequency of the injection field on the dynamics and synchronization of semiconductor lasers are studied numerically. The fluctuation amplitude and frequency of the injection field are controlled by external modulation of the master laser. In the simulation, we use a modified correlation coefficient named similarity index to evaluate the synchronization performance. The results show that frequency and fluctuation amplitude of the injection field play important roles on the dynamics and synchronization quality of the system. Large fluctuation amplitude and moderate fluctuation frequency of the injection field will contribute to the synchronization of the two lasers. The results can also be extended to the analysis of chaotic signals.

Numerical Analysis on Chaos Synchronization in Semiconductor Lasers Subject to a Common Drive Signal

We numerically observe chaos synchronization of two semiconductor lasers commonly driven by a chaotic semiconductor laser subject to optical feedback. We observe strongly correlated chaos synchronization between the two response lasers even when the correlation between the drive and response lasers is low. We show that the cross correlation between the two responses is larger than that between drive and responses over a wide parameter region.

SOA-Induced Noise Effects on Chaos Generation and Synchronization of Semiconductor Lasers

In this letter, the noise effects induced by semiconductor optical amplification within a cavity with external optical feedback are studied, in terms of chaos complexity of the generated emitter's signal, as well as the ability of an appropriate receiver to synchronize with the emitted signal in a chaos-based optical communication system.

Common-chaotic-signal induced synchronization in semiconductor lasers

We experimentally and numerically observe synchronization of two semiconductor lasers commonly driven by a chaotic semiconductor laser subject to optical feedback. Under condition that the relaxation oscillation frequency is matched between the two response lasers, but mismatched between the drive and the two response lasers, we show that it is possible to observe strongly correlated synchronization between the two response lasers even when the correlation between the drive and response lasers is low. We also show that the cross correlation between the two responses is larger than that between drive and responses over a wide parameter region.

Characteristics of Chaos Synchronization in Semiconductor Lasers Subject to Polarization- Rotated Optical Feedback

We numerically investigate the detailed characteristics of chaos synchronization in semiconductor lasers subject to polarization-rotated optical feedback. The emission of the dominant TE mode of a drive laser is rotated 90 deg and fed back to the laser with time delay. The polarization-rotated TE mode is also injected with time delay into the TM mode of a second laser. Two types of synchronization with different time-lags are found, as in the case for synchronization in semiconductor lasers with nonrotated optical feedback. However, a significant difference to the nonrotated optical feedback case is that neither of the two types of synchronization requires matching of optical carrier frequency between the two lasers.

Effect of parameter mismatch on the synchronization of chaotic semiconductor lasers with electro-optical feedback.

We investigate the detrimental effects of parameter mismatch on the synchronization of semiconductor lasers with electro-optical feedback, whose intensity dynamics can display a hyperchaotic behavior. Analytical techniques are developed to study the statistical properties of the synchronization error as a function of the various types of mismatches. The multiple mismatch case, which is of high experimental interest, is also studied and some compensation conditions allowing the improvement of the synchronization are derived. The analytical predictions are confirmed by numerical simulations and by some experimental measurements.

Anticipating synchronization based on optical injection-locking in chaotic semiconductor lasers

Numerical studies for anticipating chaos synchronization in semiconductor lasers with optical feedback are presented. Anticipating chaos synchronization in a delay-differential system is believed to occur when all chaos parameters between the two systems are perfectly coincident with each other. However, we find new schemes of anticipating chaos synchronization when the parameters between the two systems have mismatches. Under these conditions, the time lag between the two laser outputs is equal to that of anticipating chaos synchronization, but the physical origin of the phenomenon comes from optical injection-locking or amplification in laser systems. We show the evidence of such chaotic synchronization using trajectories in the phase space of the phase difference and the carrier density in the laser oscillations.

Optimization and stability boundaries for the synchronization of semiconductor lasers with external optical feedback.

We perform a stability and optimization analysis for the synchronization of unidirectionally coupled external-cavity semiconductor lasers. Using rigorous stability criteria, we qualitatively derive the boundaries of the high-quality synchronization basin. The underlying influence of Hopf bifurcations on the stability of the synchronization manifold is also investigated.

Synchronization of chaos due to linear response in optically driven semiconductor lasers.

This paper presents physical aspects on chaos synchronization in semiconductor lasers (SLs) by studying synchronization from a fundamental standpoint of driven damped oscillators. We investigate the simple configuration, a chaotic master SL with optical feedback and a solitary slave SL. The point we emphasize is that the slave laser is regarded as a damped oscillator with relaxation oscillation. Linear stability analysis demonstrates that strong injection can enhance the damping of the slave SL. Consequently, the slave SL can have broad and nearly flat spectral characteristics in its driven response, which is sufficient for covering the broadband chaotic driving signal from the master SL. Numerical simulations verify that the slave SL subject to such strong injection synchronizes well with the chaotic driving signal. We consider that the synchronization phenomenon results from a quasilinear driven response of the slave SL with the remarkable spectral characteristics. Moreover, we discuss this type of chaos synchronization in comparison to anticipating-chaos synchronization occurring in our case from conventional complete synchronization theories, and clarify the different physical aspects of the chaos synchronization scheme. We also show that our analysis agrees well with the earlier experiments that could not have been explained by complete synchronization theory.