New PhD Project Offers
2012-08-EM Nano-structured materials for advanced photonic components and laser applications (UB1-ICMCB/ISM, IST-ICEMS)
The next generation of optical materials will be based on nano-composites. The project aims to structure the optical properties of a glass at the different scales. For this purpose it is necessary to control phase separation, oxydation degree etc. locally, using external interactions (laser, thermal, electric field...). The goal desired and the challenge for optical applications, is to control the structuring of the materials at the nanometer scale and at the micrometer scale but more importantly at the intermediate scale (~100 nm) while maintaining the optical quality. This achievement is not trivial since the bottom up approach face defect of organization for instance which rule out most of possible applications. A combined bottom up and top down approach using structuring by external stimuli will allow the breakthrough.
Glasses are widely used in photonics because of their good optical properties and their low production cost. However, to obtain Second-Order Nonlinear (SON) optical properties in a glass, such as frequency conversion for laser applications, it is necessary to break its natural centrosymmetry. This can be obtained either by the precipitation of nonlinear optical crystals, or by thermal poling treatment. The main aim of the present project is to combine both process to develop new polarized nanostrutured glass ceramics with high second order non linear optical response.
The research work will be based on:
- Controlled elaboration of nanostructures in glass - (partner IST)
- Thermal polarization of glass nanocomposites - (ICMCB)
- Study of the “structure – SON” correlation by combining a set of structural characterizations and state of the art non linear optical characterization tools - (ISM)
- Spatial control of the SON properties at the micrometer level by controlled laser irradiation in order to achieve quasi phase matching for efficient frequency conversion - (ICMCB / ISM)
- Laser damage test on high power laser - (CEA-CESTA)
The project partners combine all the necessary expertise and realize the breakthrough for practical application. This program will be also an opportunity for prmoting post-graduated education, and offering to a graduate student the best research environment.
Project Partners and their Roles
ICEMS, Department of Chemical Engineering, IST Lisbon has extensive knowledge in glass preparation and glass characterization. Particularly, they have recently developed glass ceramics within the niobium/silicate/germanium systems .Those materials have been reported to exhibit nanoscale crystallization allowing a good transparency and having a high potential for application in photonics.
Institut des sciences Moléculaires (ISM) Bordeaux and Institut de Chimie de la Matière Condensée de Bordeaux” (ICMCB)
The Bordeaux groups have developed expertise in the design and development of materials with nonlinear optical properties (ICMCB) and in the characterization and modeling of optical properties (ISM). Since ten years, their work in glass poling has permitted to progress in the understanding of the polarization mechanisms and thus to permit a real control of the physical properties induced by poling.
CEA-CESTA (Laboratoire des Procédés Optiques) organism in Bordeaux is already involved in similar research topics. In the context of the Laser Megajoule, they need to design new large based-glass optics for frequency conversion useful for very high power lasers.
Figure: (left) High resolution SEM image of LiNbO3 crystals in a silicate matrix. (right) Second harmonic generation images showing the second order optical response of the precipitated crystals in the glass matrix.