Structuration 1D et 2D de matériaux diélectriques par ablation laser nanoseconde : applications aux couches minces et monocristaux de LiNbO3 et couches minces de TiO2

Abstract : Micro and nano structuring of materials constitutes a field of very promising research and development whose success will make it possible to carry out very important progress of photonic technology. From the material point of view, the use of dielectrics such as LiNbO3 or TiO2, which have specific properties different from those of the semiconductors, is likely to widen the performances of the photonic components to be developed. Moreover, the utilization of these materials in the form of thin layers makes it possible to release from limitations imposed by the bulk materials. In this work, we were interested in the realization of µ-structures 1D and 2D by using nanosecond laser ablation of lithium niobate thin layers and monocrystals as well as thin layers of TiO2. LiNbO3 thin films were deposited by RF magnetron sputtering technique on sapphire while TiO2 layers were carried out by using sol-gel method on glass substrates. Ablations were performed with a nanosecond KrF excimer laser (ATLEX 300 IF Model). The ablation of samples was carried out with a mask of 10 µm of diameter. The frequencies applied vary from 10 to 100 Hz and the fluences from 0.3 to 2.3 J/cm2. Structures were observed using optical microscopy functioning in Nomarski mode and analyzed using µ-Raman spectroscopy. We particularly studied the influence of the ablation parameters (number of pulsate, fluence and repetition rate) on the structure features. For example, 5x5 holes gratings were carried out with a constant number of pulse (5pulses) and various values of fluences (0.88 with 2.093J/cm2). Our results showed that the shape of holes and their depth strongly depend on the fluence used. The best results were obtained for high fluences. For the study of the effect of the number of pulse on the ablation process, we realized a 5x5 holes grating with a constant fluence 1.467J/cm2 and a variation of pulse number from 5 to 15. The average rate of ablation decreases with the increase of the pulse number. Note that, before these studies, we studied the optical properties of our thin films by using m-lines spectroscopy. Results showed that our films are monomodes and have optical losses of about 1 dB.cm-1. The final objective of this work is to optimize the experimental ablation process in order to obtain sub-micrometric structures for applications in the field the photonic.
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Physics [physics]. Université de Metz, 2008. French


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Submitted on : Wednesday, January 21, 2009 - 4:14:36 PM
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Faiza Meriche. Structuration 1D et 2D de matériaux diélectriques par ablation laser nanoseconde : applications aux couches minces et monocristaux de LiNbO3 et couches minces de TiO2. Physics [physics]. Université de Metz, 2008. French. <tel-00354828>

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