Mid-infrared (MIR) laser sources have demonstrated diverse applications in science and technology. For spectroscopy applications, numerous molecules have unique absorption features in this range, and one needs a spectrally broad coherent laser source for parallel detection of mixtures of species. Frequency down-conversion in nonlinear optical materials via second-order nonlinear susceptibility is one of the promising techniques to generate the spectral coverage of more than an octave in the MIR, assisted by emerging novel crystals. The nonlinear light-matter interactions in such special crystals as ZnSe ceramics have not been analyzed. Additionally, through the use of high-intensity few-cycle optical pulses, high-order nonlinear effects such as four-wave mixing, multiphoton absorption, and nonlinear refraction come into play beyond conventional second-order nonlinear interaction. In this thesis, the nonlinear interactions for generating broadband MIR were studied through both experimental and numerical approaches. First, a nonlinear frequency conversion model based on random phase matching was developed in zinc-blende polycrystalline structures. Monte Carlo simulation statistically verifies that a disordered material could perform on par with a quasi-phase-matched material for frequency conversion in ultrafast interactions. Second, the nonlinear interaction in orientation-patterned GaP combined with an optical parametric oscillator was numerically analyzed. A wave propagation model discovers that third-order nonlinearity plays an important role in the process of spectral evolution. Finally, using a 2.35-µm Cr:ZnS mode-locked laser, nonlinear absorption and nonlinear refractive index were characterized in the Z-scan technique for GaP, ZnSe, GaSe, and ZGP crystals. The visualization of nonlinear interactions and the uncovering of nonlinear parameters will be a guide for optimizing experimental systems and will further advance the development of MIR laser sources.
If this is your thesis or dissertation, and want to learn how to access it or for more information about readership statistics, contact us at STARS@ucf.edu.
Doctor of Philosophy (Ph.D.)
College of Optics and Photonics
Optics and Photonics
Optics and Photonics
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Kawamori, Taiki, "Nonlinear Light-matter Interactions in Novel Crystals for Broadband Mid-infrared Generation" (2021). Electronic Theses and Dissertations, 2020-. 887.