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The Chaos in single-mode semiconductor lasers is generated by means of an optoelectronic feedback. Chaotic dynamics have been generated due to the semiconductor laser model with optoelectronics feedback under appropriate conditions. MATLAB packages have been used to simulate the behavior of the semiconductor laser diodes with optoelectronics feedback. According to the chaos simulation technique, we have studied the model properties. And determine the control parameters that lead to regular behavior. Chaotic behavior has been generated by use the simulated model of OEFSL under appropriate conditions. We have a lot consider effectively analyze the behavior of a dynamical system under the influence control parameters such as bias current (δ 0 ), feedback strength (e) and the population inversion (γ).

Recent studies demonstrated that chaotic spike sequences appearing in the context of incomplete homoclinic scenarios can be understood in terms of excitability of chaotic attractors. So far, this particular dynamic has been found in a semiconductor laser with optoelectronic feedback. Here, we show that the same phenomenology occurs also in light-emitting diodes, which are ideal candidates for the implementation of a complex network on a chip. In particular, we study the appearance of both stochastic incoherence (SI) and stochastic coherence (SC) in a single unit, as well as in two coupled units. We demonstrate experimentally and explore numerically the enhancement of SC and worsening of SI induced by coupling systems in array.

Long wavelength interferometry has been widely applied in different fields, such as infrared optics, infrared transmitting materials, high-reflective multilayer dielectric coatings for highpower laser systems. In optical metrology, long-wave interferometers are also employed for shape measurement of reflective rough surfaces and for testing optical systems that requires deep aspherics. An advantage of using longer wavelength is that the aspheric departure from the best fit reference-sphere, in unit of the probing wavelength, is reduced at longer wavelength, thus allowing one to obtain an interferogram of the deep aspheric under test. This leads to extension of the unambiguous distance measurement range, a well-known problem in interferometric metrology, where the essential difficulty relates to the interferometric fringe order, which cannot be determined unambiguously from a single measurement of phase interference. This problem is also of particular significance in digital holographic and interferomety based applications where digital processing of the recorded interferogram makes it possible to extract quantitatively amplitude and phase of the numerically reconstructed wavefront (Cuche el al., 1999a, 1999b; Vest, 1979; Yaroslavsky & Eden, 1996). Digital holography based imaging techniques provide real time capabilities to record also three-dimensional objects using interference between an object wave and a reference wave captured by an image sensor such a CCD sensor. Three-dimensional 3D information of the object can be obtained from the numerical reconstruction of a single digitally recorded hologram, since the information about the optically interfering waves is stored in the form of matrices. The numerical reconstruction process offers many more possibilities than conventional optical processing (Goodman & Lawrence, 1967; Stetson & Powell, 1966; Stetson & Brohinsky, 1985). For example, it is possible to numerically focus on any section of the three dimensional volume object without mechanical focusing adjustment (Grilli et al., 2001; Lai et al., 2000), correct optical components defects such as lens aberrations or compensate the limited depth of field of an high magnification microscope objective. Full digital processing of holograms requires high spatial resolution sensor arrays with demanding capabilities for imaging applications and non destructive testing. In this regard, several new recording materials and optoelectronic sensors have been devised for

Chaotically spiking attractors in semiconductor lasers with optoelectronic feedback have been recently observed to be the result of canard phenomena in three-dimensional phase space (incomplete homoclinic scenarios). Since light-emitting diodes display the same dynamics and are much more easily controllable, we use one of these systems to complete the attractor analysis demonstrating experimentally and theoretically the occurrence of complex sequences of periodic mixed-mode oscillations. In particular, we investigate the transition between periodic and chaotic mixed-mode states and analyze the effects of the unavoidable experimental noise on these transitions.

Synchronization phenomena have been the subject of intense studies since their first observation by Huygens in pendulum clocks. The subsequent discovery of deterministic chaos introduced a new kind of an oscillating system, a chaotic oscillator. In the late 1980s researchers turned their attention to the synchronization properties of chaotic systems (1–4), occurring when two, or more, chaotic oscillators are coupled, or, in case of the unidirectional synchronization, when a chaotic oscillator (master) drives another chaotic oscillator (slave). Despite their unpredictable nature, whose most remarkable feature is the exponential divergence of trajectories starting with infinitely close initial conditions, synchronization of chaotic systems is a phenomenon well established experimentally and reasonably understood theoretically. The increasing interest in chaotic synchronization is motivated by its potential applications. Clear understanding of these phenomena and the dynamical mechanisms behind them opens new opportunities for applications in different fields of science. In biology, for instance, a challenging problem is to understand how a group of cells or functional units, each displaying complicated behavior, can interact with one another to produce a coherent response on a higher organizational level. In secure communications, a message can be hidden in the output of a chaotic system during transmission and can be recovered by using a copy of the original system, synchronized to the first (5). In this context, the investigation has been focused on chaotic optoelectonic devices. Within the variety of dynamical regimes observed in semiconductor devices, chaotically spiking attractors play a special role. Typical time traces consist of large pulses separated by irregular time intervals in which the system displays small-amplitude chaotic oscillations. These erratic –though fully deterministic– sequences of pulses, mimic the dynamics experimentally observed in neurons (6) and many hypothesis have been done on their role in neural information processing (see (7) and references therein). Therefore, experiments Optoelectronic Feedback in Semiconductor Light Sources: Optimization of Network Components for Synchronization 29

The experimental evidence of the effect of femtosecond laser pulses on the spectral response of a Silicon photovoltaic cell is demonstrated and investigated. The response of this device is covering the visible to near infrared spectral region. The responsivity of the photovoltaic cell is enhanced from 0.18A/W (0.5A/W to 0.85 A/W) to 0.25A/W, this means that the conversion efficiency increases from about 9% to about 14% due to irradiation effect. All treatments and measurements have been done at room temperature. The observed enhancement is related to the appearing of nano-structured groves in the 700-900 nm range.

We report on experimental evidence of generation and control of low spiking events in a semiconductor laser. An experiment has been carried on a semiconductor laser with an electro-optic feedback, set in a parameter range where chaos occurs. The feedback is modulated by 1 kHz and 10 kHz, frequencies, 50mV amplitudes. The dependence of the injected current on the feedback fraction is observed.

The amplification of femtosecond laser has been experimentally investigated around 1.060 m m wavelength through an optical fiber based on stimulated Raman scattering (SRS) . A passively mode locked Nd:glass laser (model Timebandwidth GLX 200) giving a pulse duration of about 200 fsec at 1.060 m m wavelength and 120 mW average optical power with 100 MHz repetition rate is used as seed signal . Whereas the high repetition rate 88MHz Nd YLF laser operating at 1.053 m m with pulse duration of 120 Psec is used as pump laser of the 15 and 25 m long single mode fiber. The broadening in the time of the pulse is done in the first few meters of the optical fiber and then amplified due to the energy transfer from pump laser source to the seed laser pulse . The results showed that the peak power conversion efficiency exceeds 45% and the on-off peak gain is about 2 dB. The peak wavelength shift is about 0.3 nm when the optical fiber is forward pumping by Nd-YLF laser. The self phase modulation (SPM) leads to compress the laser spectral width from 6.96 nm to 5 nm with small effect on the maximum nonlinear phase shift.

We demonstrate experimentally and theoretically the existence of slow chaotic spiking sequences in the dynamics of semiconductor devices (lasers and LED) with ac-coupled optoelectronic feedback. The timescale of these dynamics is fully determined by the high-pass filter in the feedback loop and their erratic, though deterministic, nature is evidenced by means of the interspike interval (ISI) probability distribution. We eventually show that this regime is the result of an incomplete homoclinic scenario to a saddle-focus, where an exact homoclinic connection does not occur. The synchronization scenarios have been fully investigated.

The dynamics of a semiconductor laser with AC-coupled nonlinear optoelectronic feedback has been experimentally studied. A period doubling sequence of small periodic and chaotic attractors is observed, each of them displaying excitable features. This scenario is found also in a simplified physical model of the system, thus extending the concept of excitability, usually associated to fixed points, also to the case of higher-dimensional attractors.

Femtosecond laser pulse propagation in monomode optical fibers is demonstrated and investigated numerically (by simulations) and experimentally in this paper. A passively mode locked Nd:glass laser giving a pulse duration of about 200 fsec at 1053 nm wavelength and 120 mW average optical power with 100 MHz repetition rate is used in the experimental work. Numerical simulations are done by solving the nonlinear Schrödinger equation with the aid of Matlab program. The results show that self phase modulation (SPM) leads to compression of the spectral width from 5 nm to 2.1 nm after propagation of different optical powers (34, 43, 86 and 120 mW) in fibers of different length (5, 15, 35 m). The varying optical powers produced a varying phase shift. The output spectral width also changed with the fiber length at a given peak power. © 2009 World Scientific Publishing Company.

The Chaos in the single-mode semiconductor lasers is generated by means of an optoelectronic feedback. Chaotic been generation under selected experimental initial condition of semiconductor laser model with optoelectronics feedback under appropriate conditions. MATLAB packages using to simulate the model behavior of semiconductor laser diodes with optoelectronics feedback. The Chaos in the single-mode semiconductor lasers is generated by means of an optoelectronic feedback. And result generated due to the simulated models. The existence of slow chaotic spiking sequences in the dynamics of a semiconductor laser with an optoelectronic feedback demonstrated experimentally and theoretically.

We demonstrate experimentally and theoretically the existence of slow chaotic spiking sequences in the dynamics of a semiconductor laser with ac-coupled optoelectronic feedback. The timescale of these dynamics is fully determined by the high-pass filter in the feedback loop and their erratic, though deterministic, nature is evidenced by means of the interspike interval (ISI) probability distribution. We eventually show that this regime is the result of an incomplete homoclinic scenario to a saddle-focus, where an exact homoclinic connection does not occur.