Fabrication and Characterisation of Photonic Devices in Laser

DANIEL JAQUE GARCIA, AIRAN RODENAS, JORGE LAMELA, FRANCISCO JAQUE, GUSTAVO TORCHIA, C. MÉNDEZ Y L. ROSO

Hangzhou, China

Simposio; Progress In Electromagnetics Research Symposium; 2008

Femtosecond laser writing has been used to modify, at the micrometric scale, the local refractive index of solid state laser media leading to the creation of optically active photonic devices. Due to the possibility of optical amplification, the obtained devices have been demonstrated to be capable of light generation and manipulation. As an example, femtosecond laser writing has been used to fabricate optically active channel waveguides and non-collinear diode pumped lasers. In order to evaluate the potential application of the obtained photonic structures it is necessary to investigate how the original properties of the irradiated laser media have been modified by the physical phenomena at the origin of the permanent modifications induced after femtosecond irra-diation. In this work we present a novel approach to this problem consisting in the combination of Confocal-Micro-Luminescence and Near Field Optical Microscopy. We have found that the spectroscopic properties of the active ions, responsible of optical gain, are quite sensible to the structural modifications induced by femtosecond pulses. Taking advantage of this fact we have been able to locate spatially a rich variety of effects activated by femtosecond pulses including local compression and dilatation, local amorphization and local crystallographic re-orientations. The results obtained from the analysis of Confocal-Micro-Luminescence have been found in excellent agreement with the micro-pictures obtained with the Near Field Scanning Microscope which has also revealed the presence of defect formation, self-focusing induced micro-explosions and shock wave propagation above the elastic limits of the irradiated material. The information provided from both techniques has been found of great relevance not only from the applied point of view but also from the fundamental one since it gets information about the light matter interaction at the femtosecond time scale.