Frequency conversion in conjugated organic molecules and its applications to ultra-fast pulse diagnostic and imaging
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PublisherThe University of Arizona.
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AbstractThis dissertation is devoted to the study of third-harmonic generation (THG) in push-pull chromophore-doped polymer films. This kind of films, with amorphous structure, exhibit null second harmonic generation but strong THG when pumped at the fundamental wavelengths within the telecommunication range (1.4-1.6 μm). It is demonstrated that at 1550 nm, micrometer-thick samples generate up to 17 muW of green light with an input power of 250 mW delivered by an optical parametric oscillator. This high conversion efficiency is achieved without the use of phase matching or cascading of quadratic nonlinear effects and it is due to high values of the third-order nonlinear susceptibility combined with weak film absorption at the third harmonic wavelength. The efficient THG process opens the doors to low cost and sensitive third-order optical autocorrelation and cross-correlation applications. So, in addition to the basic research performed about the characterization of the THG in push-pull chromophore-doped polymer films, two applications are demonstrated. The first is the complete diagnostic of femtosecond pulses by THG-Interferometric Autocorrelation and by THG Frequency-Resolved Optical Gating. The second is the THG-Cross-correlation Time-Gated Imaging of objects embedded in highly scattering conditions.
Degree ProgramGraduate College