| Femtosecond-lasers represent a source for electric field pulses which can have field intensities approaching and even exceeding the atomic binding field. For an electric field of this order, the polarization response of the medium changes from linear to nonlinear. For transparent media, depending on the field intensity the laser pulse is either nonlinearly absorbed or, at lower field intensities, modifies medium as it propagates, modulating its own spectrum. Nonlinear absorption has direct applications to micromachining of photonic devices. We discuss the effect of different laser parameters such as the repetition rate and number of pulses in the femtosecond-laser generated structures. Additionally, we investigate the transmission losses, bending loss, supported electromagnetic modes and index of refraction profiles of optical interconnects fabricated through femtosecond micromachining we investigate. This dissertation also covers experiments on the propagation of femtosecond pulse confined in structures whose diameter is below the wavelength of the incident fight, silica based nanowires. We demonstrate the possibility of making sub-micrometer diameter silica fibers and discuss effects of their diameter-dependent dispersion and enhance nonlinearity for femtosecond laser pulse propagation. The nonlinearity and dispersion is measured as a function the nanowire diameter and our results confirm the theoretical predictions for the enhancement of the nonlinearity and the effect of high dispersion. Both technologies, nanowires and femtosecond manufactured waveguides, represent alternatives for photonic circuits interconnects, but at nanometer and micrometer scales, respectively. |
