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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

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