Chaos In Laser Research Articles

Study on the method of controlling chaos in an Er-doped fiber dual-ring laser via external optical injection and shifting optical feedback light

Controlling chaos in an erbium-doped fiber dual-ring laser is studied by injecting an external light and shifting the phase of an optical feedback light. First, the parameters of the externally injected optical signal are adjusted to bring the chaotic laser into a single-period state and a multiperiod state, respectively. In addition, the single-mode locking in a single ring of the laser as well as the dual-mode locking in dual ring of the laser are found. Secondly, the method of optical feedback is used to stabilize chaos by controlling the parameters of the optical devices in an external optical path. We show that the optical negative feedback can stabilize the chaotic laser into a single-period state, while the optical positive feedback can stabilize the chaotic laser into another single-period state and a period-doubling state. Lastly, various dynamical states are produced in the laser by shifting the phase of the optical feedback light.

Self-Induced Chaos in a Single-Mode Inversionless Laser

A single-mode inversionless laser with a three-level phaseonium as an active medium can by itself exhibit complex nonlinear dynamics. Nonlinear interaction between two spectrally separated gain regions of the phaseonium and a lasing field gives rise to instabilities and chaotic self-pulsations of a type not observed in conventional lasers with population-inverted gain media. We calculate the bifurcation diagram and uncover multistability and a torus-doubling cascade in transition to chaos.

Phase-locking phenomenon in a semiconductor laser with external cavities

Phase-locked solutions are found numerically in a semiconductor laser with one and two external cavities. Different periodic, quasiperiodic, chaotic, and steady-state regimes form Arnold's tongues in bi-dimensional parameter spaces of the length and feedback strengths of the external cavities and the pump parameter. This rich structure gives additional possibility for controlling complex dynamics and chaos in a semiconductor laser with external cavities by properly adjusting their lengths and feedback strengths.

Chaos-pass filtering in injection-locked semiconductor lasers

Chaos-pass filtering (CPF) of semiconductor lasers has been studied theoretically. CPF is a phenomenon which occurs in laser chaos synchronization by injection locking and is a fundamental technique for the extraction of messages at the receiver laser in chaotic communications systems. We employ a simple theory based on driven damped oscillators to clarify the physical background of CPF. The receiver laser is optically driven by injection from the transmitter laser. We have numerically investigated the response characteristics of the receiver when it is driven by periodic (message) and chaotic (carrier) signals. It is thereby revealed that the response of the receiver laser in the two cases is quite different. For the periodic drive, the receiver exhibits a response depending on the signal frequency, while the chaotic drive provides a frequency-independent synchronous response to the receiver laser. We verify that the periodic and chaotic drives occur independently in the CPF response, and, consequently, CPF can be clearly understood in the difference of the two drives. Message extraction using CPF is also examined, and the validity of our theoretical explanation for the physical mechanism underlying CPF is thus verified.

Laser Chaos Induced by Delayed-Feedback and External Modulation

Electronic-controlled routes to chaos in a quantum-well laser diode are produced using a delayed-feedback technique. By introducing an extra delayed-feedback control term cSn(t-τ), chaotic light output can be achieved at a relatively low bias and a small modulation depth. The interaction between external modulation and delay forms quasi-two-period routes to chaos by varying modulation amplitude b and intermittency routes to chaos by varying modulation frequency f0. Numerical analysis and experimental results agree qualitatively.

Wave Chaos in Real-World Vertical-Cavity Surface-Emitting Lasers

We report the onset of wave chaos in a real-world vertical-cavity surface-emitting laser. In a joint experimental and modeling approach we demonstrate that a small deformation in one layer of the complicated laser structure changes the emission properties qualitatively. Based on the analysis of the spatial emission profiles and spectral eigenvalue spacing distributions, we attribute these changes to the transition from regular behavior to wave chaos, and justify the full analogy to two-dimensional billiards by model calculations. Hence, these lasers represent fascinating devices for wave chaos studies.

Effect of a permanent magnetic field on quasi-periodic and chaotic oscillation regimes in solid-state ring lasers

Features of nonlinear dynamics of solid-state ring lasers in quasi-periodic and chaotic oscillation regimes in a magnetic field are studied experimentally. Windows of periodic and quasi-periodic regimes within the region of dynamic chaos in a monolithic ring laser with periodically modulated pumping are observed experimentally for the first time. It is shown that an applied magnetic field changes the boundaries of the existence of various nonstationary regimes. It is established that, under certain conditions, lasing regimes can be switched in magnetic fields with strengths of ∼1 Oe.

Experimental synchronization of chaos in diode lasers with polarization-rotated feedback and injection

We demonstrate experimental chaos synchronization between two chaotic semiconductor lasers subjected to polarization-rotated optical feedback and unidirectional injection. This system allows high-quality synchronization to be obtained between dissimilar lasers in a wide range of chaotic operating regimes. Another feature of this system is its operation at high characteristic frequencies, taking advantage of all-optical implementation. Time series and RF spectra showing synchronization are confirmed by high correlation coefficients in excess of 0.85.

Synchronization of chaos in microchip lasers and its communication applications

We overview some experimental and numerical demonstrations on the synchronization of chaos and its communication applications using Nd:YVO 4 microchip solid-state lasers. Synchronization of chaos is achieved with several coupling configurations. Several encoding and decoding schemes for communication applications are also demonstrated by using the synchronization of chaos in microchip lasers. A new approach to secure communications using chaos based on information theoretic security is introduced. To cite this article: A. Uchida, S. Yoshimori, C. R. Physique 5 (2004).

Chaotic radar using nonlinear laser dynamics

A novel chaotic radar (CRADAR) system utilizing laser chaos is investigated both numerically and experimentally. Compared with conventional radars, the proposed CRADAR has the advantages of very-high-range resolution, unambiguous correlation profile, possibility of secure detection, low probability of intercept, and high electromagnetic compatibility. Generated by an optically injected semiconductor laser, chaotic waveforms with bandwidths larger than 10 GHz can be readily obtained. In this paper, the time series, the phase portraits, and the power spectra of the chaotic states are presented. The correlation traces between the signal and the reference waveforms are plotted. The peak sidelobe level with different correlation lengths is investigated. The capability of anti-jamming and the performance under additive white Gaussian noise are studied. To show the feasibility of CRADAR, proof-of-concept experiments using a pair of planar antennas with a 1.5-GHz bandwidth covering the range from 1.5 to 3 GHz are demonstrated. A range resolution of 9 cm is achieved, which is currently limited not by the bandwidth of the chaotic states but by the detection bandwidths of the real-time oscilloscope and the antennas used.

Excitation of dynamic chaos in a monolithic ring chip laser upon periodic modulation of mechanical stresses in the active element

The peculiarities of nonlinear dynamics of solid-state bidirectional ring Nd:YAG chip lasers are studied theoretically and experimentally during periodic modulation of mechanical stresses in the active element. It is shown that modulation of mechanical stresses is an effective method for exciting dynamic chaos in a monolithic chip laser.

Observation of period-doubling bifurcations in a femtosecond fiber soliton laser with dispersion management cavity

We report on the experimental observation of period-doubling bifurcation and period-doubling route to chaos in a femtosecond soliton fiber laser passively mode locked by using the nonlinear polarization rotation technique. Increasing energy of the solitons circulating in the laser cavity, it was revealed that the intensity pattern of the output solitons experiences a period doubling route to chaos. Period-doubling route to chaos is a universal property of the nonlinear dynamic systems transiting from a stable state to a chaotic state. This experimental result shows that the nonlinear propagation of soliton pulses in the laser cavity is an intrinsic dynamic process, which follows the universal laws of the nonlinear dynamic systems.

Chaotic synchronization and evolution of optical phase in a bidirectional solid-state ring laser.

We present results on experimental and theoretical studies of chaos in a solid-state ring laser with periodic pump modulation. We show that the synchronized chaos in the counter-propagating waves is observed for the values of pump modulation frequency fp satisfying the inequality f1 < fp < f2. The boundaries of this region, f1 and f2, depend on the pump-modulation depth. Inside the region of synchronized chaos we study not only dynamics of amplitudes of the counter-propagating waves but also the optical phases of them by mixing the fields of the counter-propagating waves and recording the intensity of the mixed signal. We demonstrate experimentally that in the regime of synchronized chaos the regular phase jumps appear during intervals between adjacent chaotic pulses. We improve the standard semi-classical model of a SSRL and consider an effect of spontaneous emission noise on the temporal evolution of intensities and phase dynamics in the regime of synchronized chaos. It is shown that at the parameters of the experimentally studied laser the noise strongly affects the temporal dependence of amplitudes of the counter-propagating waves.

Generalized synchronization of chaos in erbium-doped dual-ring lasers

We investigate chaotic synchronization in the generalized sense in unidirectionally coupled erbium-doped fibre dual-ring lasers. Numerical simulation shows that no matter whether the two different erbium-doped fibre dual-ring lasers are chaotic or not before coupling, they show generalized synchronization with a suitable unidirectional coupling coefficient under which the maximum condition Lyapunov exponent is negative. We also use the auxiliary system approach to detect the generalized synchronization.

Synchronization of chaos in microchip lasers by using incoherent feedback.

We propose a chaos-synchronization scheme using incoherent feedback to the pumping power in two microchip lasers. The population inversion of the slave laser is controlled for synchronization by using the detected signals of the peak heights of chaotic pulse intensities in the two lasers. Matching of the optical frequencies between the two lasers (i.e., injection locking) is not required for synchronization using this method. We numerically demonstrate the incoherent feedback method and investigate synchronization regions against parameter mismatching between the two lasers. Synchronization is maintained within a mismatching of 1% for all laser parameters, which implies that the difficulty in reproducing the synchronized laser pulses is very useful for applications of secure optical communications.

15-GHz message transmission based on synchronization of chaos in semiconductor lasers

Sinusoidal message transmission up to 1.5 GHz is performed based on synchronization of chaos in experimental nonlinear systems of semiconductor lasers with optical feedback. In the chaotic systems the message is almost entirely suppressed in the receiver output, even if the message has nonnegligible power in the transmitter.

Chaotic lag synchronization and pulse-induced transient chaos in lasers coupled by saturable absorber

Two lasers coupled via a common intracavity SF 6 saturable absorber show a cooperative coupling effect, instead of the most common competitive coupling. The dynamics of the system is very rich and includes strong pulsing, which may localize the non-linear interaction in time. Two chaotic regimes are analyzed experimentally and numerically: a chaotic lag synchronization resulting from an almost continuous interaction and a transient chaos resulting from a pulsed interaction.

Synchronization of feedback-induced chaos in semiconductor lasers by optical injection

In this paper, synchronization of chaotic oscillations in semiconductor lasers by optical injection in a transmitter-receiver configuration is studied numerically. A chaotic signal is generated from a semiconductor laser with optical feedback in the transmitter and is injected into the receiver laser without optical feedback. We examined the conditions of chaotic synchronization in the system. As a result, we observed complete chaos synchronization within a finite area of very small parameter mismatch between the two laser systems. In addition, chaotic oscillation synchronized by amplification phenomena was observed in the ordinary injection-locking regime with higher optical injection ratios. We demonstrated that synchronization of chaotic oscillations by amplification results from a kind of injection locking under chaotic light injection and is very tolerant to the parameter mismatch between the two lasers, in contrast to the complete synchronization case.

Observation of Polarization Instabilities and Chaos in a Two-Photon Laser

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Daniel J. Gauthier, Olivier Pfister, William J. Brown, and Michael D. Stenner, "Observation of Polarization Instabilities and Chaos in a Two-Photon Laser," Optics & Photonics News 12(12), 58-58 (2001) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Optical-communication systems based on chaos in semiconductor lasers

Chaotic optical-communication systems using semiconductor lasers are studied. The dynamics, synchronization, and message encoding and decoding are modeled and studied numerically and experimentally for two systems which are based on optical injection and delayed optoelectronic feedback of semiconductor lasers, respectively. An optically-injected single-mode semiconductor laser is a nonautonomous nonlinear system of three dynamical variables. It has phase-sensitive dynamics that follow a period-doubling route to chaos. A single-mode semiconductor laser with delayed optoelectronic feedback is an autonomous, delayed-feedback nonlinear system with only two dynamical variables, but its dimension can be very high when the delay time is large. It has phase-insensitive pulsing dynamics that follows a quasi-periodic route to chaotic pulsing. Stable synchronization for both systems are devised, modeled, and studied numerically and experimentally. Message encoding schemes for chaotic communication systems based on the concept of chaos modulation are devised and implemented for both systems to encode and decode optically transmitted messages.