Photonic crystals (PhC), are periodic dielectric media that possess photonic band gaps, a frequency range in which certain light wavelengths, or colors, are completely reflected. These ordered media are the optical equivalent of electronic semiconductors, such as silicon, that pervade our daily lives. From the precision dispersion tailoring of propagating modes, to compact resonant nanocavities, to the generation of novel light sources for quantum information, we are now able to engineer optical properties with prescriptive control over light-matter interaction at sub-diffraction-limited scales.
This thesis reports on enhanced nonlinear effects in III-V photonic crystals, in both waveguide and cavity configurations. A significant portion of this thesis focuses on ‘slow-light’ effects in GaInP photonic crystal waveguides (PhCWG). The origin of slow-light in photonic crystals arises from coherent Bragg reflections due to the periodic PhCWG lattice. The result is the light effectively travels at a decreased group velocity, increasing light intensity inside the photonic crystal even though small energies are injected.
In the first part of this thesis, strong light-matter interaction is demonstrated experimentally through slow-light enhanced self-phase modulation (SPM) of optical pulses due to the Kerr effect. Analytic formulations were also conducted to discern the limitations due to multi-photon absorption and free-carrier effects. Building on these spectral-domain experiments, we next investigated temporal soliton effects with intensity autocorrelation in the time-domain. A third set of PhCWG experiments provide the main result of this thesis: the first experimental demonstration of temporal soliton phase in nanoscale waveguides. These observations were greatly facilitated by the introduction of the GaInP material, which completely suppresses two-photon nonlinear absorption at 1.55 μm wavelength employed in the experiments. Finally, the dynamic response of a GaAs photonic crystal nanocavity was investigated in a pump-probe configuration, demonstrating low-energy threshold all-optical modulation at time scales on the order of ten picoseconds.
|Adviser||Chee Wei Wong|
|Subjects||Electrical engineering; Electromagnetics; Optics|
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