Photonics in microelectronic and biological applications

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Photonics is contributing more and more in different fields of research. The two photonics applications described in this proposal are in the fields of ophthalmic micro-surgery and microelectronics. Femtosecond lasers are extensively used for micro-machining because of the very clean and precise cut that is possible with these ultrashort pulse systems. This precise ablation is now being transposed to transparent media for surface but also sub-surface applications such as micro-surgery of the eye. For example, by generating micro-plasmas inside the corneal stroma, it is possible to achieve a cutting effect inside the tissue while leaving the anterior layers intact. This cutting effect is produced by a cavitation that accompanies plasma-mediated ablation. But incisions require a large number of pulses with the successive pulses being scattered by the cavitation bubbles produced by earlier pulses. The object of this research is to optimize the laser conditions (wavelength, energy) to minimize this scattering to achieve the closest spacing of these cavitation bubbles and thus the most efficient incision. Silicon is the material of choice in the microelectronic industry. The integration of optoelectronic components on an all Si matrix would considerably simplify the conception and fabrication of optoelectronic devices, allowing, for example, computers to operate faster by replacing electrical connections with optical ones. But Si is a poor light emitter; its indirect band gap impedes radiative transitions. However, Si nanostructures (Si-nc) can emit light and several processes, compatible with those used in the micro-electronics industry, are being explored in order to produce Si-nc with tailored luminescent properties. Extensive studies are being carried out to better understand the basic mechanisms of nanocrystal production and growth. The goal of this research is to maximize emission and shape the luminescence spectrum.