In this paper, we present a theoretical evaluation of curved Er 3 ‡ -doped LiNbO 3 waveguide statistical parameters. We calculate the output mean photon number, the standard deviation, the Fano factor and the statistical uctuations. Simulations are performed using the small-gain approximation and the photon statistics master equation of the linear ampli®er, transposed to the case of curved ampli®ers. The evolution of the above-mentioned device characteristics with various pump powers, waveguide lengths and signal wavelengths are also presented.

We investigated the process of laser micro-drilling of copper and iron by using nanosecond laser-pulses at 532nm wavelength in atmospheric air. We analyzed the ablated volume, ablation rate, crater diameter, and craters quality as functions of laser-fluence and beam-diameter. The fluence was varied between 10 and 6000 J/cm 2 by changing the laserenergy. The results indicate that the ablated volume increases linearly with fluence, whereas the ablation rate and crater diameter increase linearly with the fluence's square root. The ablated volume, ablation rate, and crater diameter, increase with thermal diffusivity of the materials. Additionally, the ablation threshold-fluence is demonstrated to be directly related to the optical penetration depth.The ablated volume, ablation rate, and crater diameter were further assessed for beam-diameters in the range of 10-50 microns by translating the targets away from the focal plane while keeping a constant fluence. The results indicate that the ablated volume increases linearly with beam-diameter, whereas the ablation rate and crater diameter increase linearly with the inverse of the beam-diameter's square root.To investigate the craters quality we measured the dimension of the thermally affected zone (TAZ) around the craters as a function of fluence. At fluences up to 400 J/cm 2 , where strong ionization occurs within the plume, the crater diameter is <15 microns (comparable with beam diameter) and there is small TAZ around the craters. Further increase of the fluence leads to a significant increase of TAZ, indicating that the expanding plasma plays a major role in metals ablation in this fluence domain.

Optical hysteresis is a fundamental phenomenon that can lead to optical bistability and highspeed signal processing. Here, we present a theoretical and experimental study of the optical hysteresis phenomenon in amorphous As 2 S 3 chalcogenide based waveguide structures under surface plasmon resonance (SPR) conditions. The SPR structure is irradiated with low power CW Ar laser radiation at 514 nm wavelength, with photon energy near the optical band-gap of As 2 S 3 , in a Kretschmann-Raether configuration. First, we determined the incidence angle on the SPR structure for resonant coupling of the laser radiation within the waveguide structure. Subsequently, by setting the near resonance incidence angle, we analyzed the variation of the laser power reflected on the SPR structure with incident power. We demonstrated that, by setting the incidence angle at a value slightly smaller than the resonance angle, the increase followed by the decrease of the incident power lead to a wide (up to 60%) hysteresis loop of the reflected power. This behavior is related to the slow and persistent photo-induced modification of the complex refractive index of As 2 S 3 under 514 nm laser irradiation. The experimental and theoretical results are in good agreement, demonstrating the validity of the theoretical model presented here.

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Er -dopedis widely used for the fabrication of integrated optic components. In the small gain approximation and the unsaturated regime in this paper we report some original results in the evaluation ofthe spectral optical gain and spectral noise figure in the bent Er3 -doped waveguide ofthe Mach-Zehnder interferometer pumped near 1484 nm using erfc, Gaussian and constant profile of the Er ions in crystal. We used a quasi-two-level model to simulate the optical amplification in Er -doped straight and bent waveguide amplifiers and we demonstrated that rather high gains (-1.1 dB) and low noise figures (-3 .3 dB) at the end of the bent arm of the Mach-Zehnder interferometer are achievable for 100 mW input pump power. The obtained results can be used for the design ofthe integrated Mach-Zehnder interferometers and optic devices.