This PDF file contains the front matter associated with SPIE Proceedings Volume 7007, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

The paper is presenting the efforts developed in INFLPR to improve the thin films technologies to obtain utility products: sensors, photovoltaics, biocompatible coatings for medical applications, etc.A review of the different methods to obtain thin films, which characteristics depend on the technological method used are comparatively discussed. The main interest is focussed on the activities dedicated to achieve solar cells by using new substrates, different than Si and a structure of multilayers in order to improve the efficiency.

We review recent progress in the development of nanophotonic devices using the optical near-field interaction. ZnO nanocrystallites are potentially ideal components for realizing room-temperature operation of such devices due to their high exciton-binding energy and great oscillator strength. To confirm this promising optical property of ZnO, we examined the near-field time-resolved spectroscopy of ZnO nanorod double-quantum-well structures (DQWs). First, we observed the nutation of the population between the resonantly coupled exciton states of DQWs, in which the coupling strength of the near-field interaction was found to decrease exponentially as the separation increased. Furthermore, we successfully demonstrated the AND-gate operation by controlling a dipole-forbidden optical energy transfer among resonant exciton states. Our results provide criteria for designing nanophotonic devices. The success of time-resolved near-field spectroscopy of isolated DQWs described here is a promising step toward realizing a practical nanometerscale photonic switch and related devices.

Two new families of zoom optical systems, developed for industrial and medical laser applications, are introduced. First we discuss the main physical processes involved in industrial laser applications and the requirements for the optics. The spatial beam parameters are reviewed, explaining the relatively new concepts of intrinsic stigmatism and intrinsic astigmatism. Then two new zoom systems are discussed, including experimental examples: VariSpot^(R), which delivers round spots with adjustable diameters at fixed working distances, and VariFoc^TM, able to adjust spot shapes and sizes at different working distances. We conclude that these systems represent a valuable addition for industrial and medical lasers.

Output performances of Nd-based lasers that were pumped with diode lasers directly into the ⁴F_3/2 emitting level has been investigated at various wavelengths of emission. The end-pumping scheme was used to demonstrate efficient laser emission in the watt-range at 0.94 µm, 1.06 µm and 1.34 µm in Nd:YAG pumped at 885 nm. Nd:YVO₄ and Nd:GdVO₄ thin-disk lasers with high power emission at 1.06 µm were realized under multi-pass pumping at 880 nm, and for the first time laser emission at 0.91 µm was achieved in this configuration. Intracavity frequency-doubled lasers with emission in the green and blue spectral ranges were obtained. Thus, an end-pumped Nd:GdVO₄ laser with 5 W output power at 0.53 µm, and Nd:YVO4 and Nd:GdVO₄ thin-disk lasers with output power in excess of 4 W at 0.53 µm were realized. Nd-vanadates thin-disk lasers with ~1 W power into 0.45 µm 'deep-blue' visible spectra were demonstrated. Comparative results with the traditional pumping at 0.81 µm into the highly absorbing 4F5/2 level are presented, proving the advantage of the direct ⁴F_3/2 pumping.

Edge-pumped microchip laser configurations based on Yb:YAG/YAG composite gain media are presented. 90W output power with good beam quality and low wavefront distortion were obtained. Several new designs of composite gain media, like very thin disk with undoped cap and lens-like active media are presented and analyzed.

We show that the efficiency of high harmonic generation in nonlinear Thomson scattering is strongly increased in relativistic regime. This is why the Thompson scattering mechanism is more competitive compared to the standard mechanisms for the high harmonic generation at the interaction between ultra intense laser beams and electron plasmas.

In this work, nanometer thickness dielectric layers deposited from colloid solutions using irradiation with Short Wavelength (SW) in the visible domain have been investigated by the Differential Evanescent Light Intensity (DELI) method. A high intensity UV filtered irradiation lamp was used for photodepositing nano-layers, directly on glass substrates serving as waveguides. The amorphous Selenium (a-Se) nanometric thin layers were deposited as circular zones of about ~ 1 cm² area. Polypropylene and Polyethylene compounds melted on glass waveguides were also analyzed by DELI.

Due to the peculiar energy level scheme of Er³⁺, with many energetic resonances, Er-doped crystals can generate laser radiations in various wavelength domains: at 3 µm with applications in medicine and biology, at 1.5 μm (for telecommunications) and in visible (green) with potential applications in medicine. Low concentrated Er-doped crystals are suitable for 1.5 μm and green (upconversion pumped) lasers while high concentrated ones - for 3 μm emission. In this paper we discuss the possibilities and the limits of the lasers based on erbium-doped crystals using rate equations models.

When coherent light is incident upon an optically thick biological fluid having scattering centers (SC) in suspension, like whole blood, the backscattered light can be recorded, resulting an image speckle. A program was written to extract the time series from each pixel of the CDD conversion matrix. The autocorrelation time of the series was calculated and the autocorrelation time was determined on blood samples from different human subjects. The autocorrelation time was analyzed and compared with the erythrocyte sedimentation rate (ESR) measured during a standard laboratory test using the modified Westergren method. A different procedure to record the time series, using a detector and a data acquisition system was used as well and the autocorrelation time was calculated for the time series recorded using this procedure. The results of the work performed so far indicate that the two properties appear to be slightly correlated. A fast procedure for assessing the ESR is suggested.

Preliminary results for joining by laser welding of diamonded segments onto the support body of cutting tools are presented in the paper. Such tools are mainly used for cutting hard materials in construction industry. A new mechatronic equipment able to perform the complex displacement movements required by the new tehnology is also presented.

When coherent light passes through a transparent fluid having scattering centers (SC) in suspension the result of the far field interference is a "speckled" image. In suspension the SCs have a complex sediment and Brownian motion. Consequently the biospeckle image is not static but presents time fluctuations. A computer code to simulate the dynamics of the coherent light scattering on biological suspensions was written and used to investigate typical biological suspensions like erythrocytes (RBC) and milk in deionized water. The calculated far field intensity variation was analyzed with the autocorrelation function. Practical application are suggested based on the simulation results.

The paper contains a survey of the problems commonly encountered by anyone attempting to accurately determine or specify the speed of fast photodetectors, in the bandwidth range: hundreds of MHz - tens of GHz. Two techniques are presented: one determining the minimum duration of the optical pulses which can be "seen" accurately enough, and the other determining the electrical (power) spectrum of the photodetector, leading to bandwidth determination. Experimental determination of the bandwidth for two fast photodiodes is presented, using the latter technique.

The objective of this paper is to analyze a marking laser system that uses a diode pumped Ytterbium fiber laser. Starting from the phenomena of heating due to laser irradiation and the spatial profile of deposited energy we try to develop a better marking technique, including the laser-assisted coloring.

In the last decade we have applied with consistent results the integral transform technique in solving the classical heat equation for determining the thermal fields in laser-solid interaction. In the present paper we apply for the first time this powerful mathematical instrument for laser-transparent liquids interaction in order to find the thermal field of this process.

The paper presents the results of researches undertaken in the domain of realizing photoelectric incremental radial masks by generating them with laser micro-equipments and special dedicated software.

The paper treats high precision micro technologies for automate generation of linear incremental networks masks by using the photocomposition method with multiple micro photographical reductions using laser high sensitivity microsystems, for the manufacture of micro-sensors and micro-transducers for micro displacements with endowment in industrial and metrological laboratories. These laser micro technologies allow automate generation of incremental networks masks with incremental step of 0,1 µm ensuring necessary accuracy according to European and international standards as well as realization of linear incremental photoelectric rules divisor and vernier as marks ultra precise components of micro-sensors and microtransducers for micro displacements.

In micro- and nano- device fabrication technology, localized material removal is one of the basic operations for structure formation. Classical methods for structure formation on the surface of a silicon wafer are based mainly on chemical processing, starting with photo etching, chemical etching, and chemical-mechanical linearization. In order to propose new methods of higher quality from the point of view of both environment protection and processing quality, we have studied the possibility of thin films controlled removal under the action of laser radiation. We are presenting some qualitative results of laser induced surface removal of polymer thin films, of interest for microelectronic industry (e.g. photoresist), under the action of different laser sources. As laser sources we have used the most spread and commercially available laser systems with different wavelengths and pulse lengths in order to compare their action on the surfaces and to establish the characteristic parameters for removal of thin layers for surface cleaning.

In this paper we describe a traceable to the meter standard method to measure the height of an artifact used as a calibrator for observation instruments in nanotechnologies and nanosciences. The artifact is a grating specially manufactured so that its features (height, pitch, width, wall angles) are highly uniform across its area. A Linnik microscope designed for longitudinal (vertical) measurements using the principle of white light interferometry was used to determine the height of the grating. To insure the traceability of the measurements a laser source of known wavelength was used and the measurements obtained using white light were calibrated to it. The experimental data was statistically analyzed and the measurement precision was estimated to be in the range of nanometers. The data were compared with the results obtained using the TIC method with a Carl Zeiss microscope.

The paper overviews some of the most important applications of lasers in the field of microsystems (MEMS). We present applications from both technology and MEMS testing. Since these applications cover a wide range, the presentation does not aim to offer a thorough, detailed presentation of each of these, but only to underline some of the most important directions and features. We present the respective applications, their working principles, their advantages and their drawbacks. In some cases we present examples of microstructures realized by using laser techniques.

In this paper I present some techniques by which MEMS structures with sub-wavelength resolution can be obtained when using laser lithography. I concentrate on two major techniques: single photon and multi-photon absorption processes.

The microstructure of the weld and the extent to which it is different from the thermo-mechanically processed base material is strongly influenced by the thermal cycle of welding. The mechanical properties of composite weld structures in titanium alloys depend on structural characteristics of each region (weld, base material and heat affected area), influenced by the specific thermal cycle imposed during welding and the subsequent post-weld heat treatment. In order to improve the as-welded metal toughness and ductility, the welded metal was subjected to various post weld laser heat treatments, above and below beta transus temperature in a shielding atmosphere of pure argon. Standard micro-hardness measurements and tensile strength techniques showed higher mechanical properties of the heat treated samples in different conditions with respect to the base metal. Metallographic investigations attribute this to the formation of α'phases in heat treated material, especially in the weld metal.

The paper presents a study concerning the post - weld heat treatment of a duplex stainless steel. Welded joint samples were surface - treated using the same laser source adopted during welding in order to counterbalance the excess of ferrite formed in the welding process.

The paper presents the results of the experimental research regarding the microwelding of stainless steel by pulsed Nd :YAG laser (STARWELD PERFORMANCE SWP 6002 - ROFIN). The analytical and experimental investigation on laser weldability of a stainless steel allowed to draw the following conclusions. The micro-welds produced by the optimized Nd: YAG laser parameters featured a narrow and regular weld metal zone devoid of any solidification and shrinkage defects. The as weld metal structure was made up of elongated ferrite graints with limited amount of austenite, mainly located at grain boundaries.

We have developed all-solid-state continuous-wave diode end-pumped Nd:YAG and Nd:GdVO₄ lasers that were passively Q-switched by Cr⁴⁺:YAG saturable absorbers. The Nd:YAG laser delivered laser pulses with 138 mJ maximum energy and duration of 42 ns, with 3.3 W average power at 1.06 mm for 13.3 W of pump power at 807 nm. An average power at 1.06 mm of 1.4 W was obtained from Nd:GdVO₄ under pumping with 7.2 W power at 808 nm. The pulse energy and the pulse duration were 41 mJ and 40 ns, respectively, which correspond to 1 kW pulse peak power. The laser pulses characteristics are discussed for Cr4+:YAG saturable absorbers with different values of the initial transmission.

The paper presents some design elements concerning the optical pumping cavities of the laser generators with active solid medium, as well as the way of increasing their performance. We start from the fact that the laser cavity is a closed optical system, where the active laser medium and the pumping source are conjugated, in order to achieve a maximum concentration of the light flux of the pumping source towards the active medium. We discuss the simple elliptical section laser pumping cavities (with one pumping lamp) and triple elliptical (with three lamps), also presenting a series on calculus nomograms, very useful to those who design the laser generation optical pumping cavities.

Aluminium based Metal Matrix Composites (MMC) with particles reinforcement are well known materials with some positive features, such as light weight and high strength, but they present problems in chip removal processes because of their high abrasive nature. The paper presents a comparison between threads machined with traditional manufacturing processes and with laser technology, evaluating the dimensions and geometry of the threads. The analyzed materials are a non-reinforced aluminium alloy and two types of MMCs, with silicon and boron carbide particles reinforcement. Furthermore, benefits and difficulties of using the indicated machining technologies to produce threads are presented.