Non linéarités optiques dans les matériaux xérogels et polymères dopés. Application a la protection passive de senseurs contre les impulsions laser.

Benjamin Campagne 1
1 Laboratoire Charles Fabry de l'Institut d'Optique / Macsybio
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : The thesis concerns the study of some nonlinear optical properties exhibited by new organic molecules trapped in xerogels and polymers solid matrices. This work is airned to protect detectors like eyes or CCD captors against laser threat. These materials behave like passive optical limiters : the transmitted radiance decreases as an intense laser pulse interacts with the material. The trapped molecules in solid matrices are supposed to remain active during several months or years. We have showed that whatever the solid or liquid medium, the performances of protection are comparable. Arnong the numerous nonlinear mechanisms, we have studied the reverse saturable absorption (RSA) with derivated phtalocyanines and porphyrins chromophores, the nonlinear refiaction (NLR) and the two photon absorption (TPA). The various experiments with pulsed lasers of nanosecond, picosecond and sub-picosecond duration were used to estimate the contribution of the different mechanisms occuring instantaneously : we showed using Z-scan experiments that solid doped with RSA chromophores could also exhibit NLR. Quadripolar organic molecules exhibiting TPA are found to have large absorption cross section of excited states, like RSA. We finally studied induced scattering in a refiaction index matched inhomogeneous medium composed of one porous xerogel and a mixture of nonlinear solvants. To analyse and fit most of experimental results, we developped numerical simulations based on Beam Propagation Method. One isolated mechanism is not always sufficient to achieve an ideal protection. A solution is the combination of several mechanisms in order to increase the efficiency of the optical limiting system and to get a large spectral bandwidth protection.
Document type :
Theses
Complete list of metadatas

https://pastel.archives-ouvertes.fr/pastel-00713905
Contributor : Marion Avignon <>
Submitted on : Tuesday, July 3, 2012 - 9:35:46 AM
Last modification on : Thursday, January 11, 2018 - 6:26:33 AM
Long-term archiving on : Thursday, October 4, 2012 - 2:24:46 AM

Identifiers

  • HAL Id : pastel-00713905, version 1

Citation

Benjamin Campagne. Non linéarités optiques dans les matériaux xérogels et polymères dopés. Application a la protection passive de senseurs contre les impulsions laser.. Optique [physics.optics]. Université Paris Sud - Paris XI, 1999. Français. ⟨pastel-00713905⟩

Share

Metrics

Record views

510

Files downloads

700