Browsing by Subject "Optical parametric oscillation"

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    Nanosecond optical parametric oscillators generating eye-safe radiation
    (1998) Durak, Lütfiye
    In this thesis, construction and characterization of nanosecond optical parametric oscillators (OPO’s) generating eye-safe radiation are presented. These OPO’s convert the output of an Nd:YAG laser at 1.06 μ,\ι\ wavelength to 1.57 μη\ wavelength which is in the eye-safe band of the spectrum. A potassium titanyl phosphate (KTP) crystal is employed in these OPO’s. In the experiments, output signal energies, pulse durations, spectral characteristics, and divergence angles of the OPO outputs have been measured. We have obtained 35% conversion efficiency by using pump pulses having 15 rnJ energy and 7 ns pulse duration. These low energy OPO’s can be used in range finders. We have also constructed OPO’s that are pumped by 100 mJ pulses of 15 ns pulse duration, and 38% conversion efficiency was achieved. These high energy OPO’s can be used in target designators. The divergence angles of the low energy and the high energy OPO’s hav(' been measured as 4 rnrad and 3 mrad, respectively. A numerical model which takes into account the temporal and spatial beam profiles, diffraction, and absorptions in the crystal has been constructed. The model is in qualitative agreement with the experimental results.
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    Plane-wave dynamics of single crystal upconversion optical parametric oscillators
    (1999) Akgün, Gülbin
    This thesis presents our investigation of the dynamics of single crystal up- conversion optical parametric oscillators (OPO’s). In these devices, parametric generation and sum frequency generation or second harmonic generation processes are simultaneously phase matched in a single crystal for the same direction of propagation. These devices can be categorized depending on the polarization geometries of the interacting fields leading to simultaneous phase matching of the two processes. The dynamics of these OPO’s are analyzed using a discrete dynamical system representation. The dependence of the dynamics of the system on various parameters is investigated by forming bifurcation diagrams. Regions of stable steady state, multistable, periodic and chaotic operation are identified on these diagrams.