Speckle contrast reduction by linear and nonlinear photonic devices
Speckle contrast <; 3.5% was achieved by means of (i) wavelength-diversity using spectrally-broad nonlinear photonic green lasers over the 520-545nm range and (ii) polarization- and phase-diversity using birefringent nano-photonic devices.
Upconversion blue laser by intracavity frequency self-doubling of periodically poled lithium tantalate parametric oscillator.
We report a design for upconversion 435 nm blue lasers based on simultaneously fulfilling the nonlinear processes of optical parametric oscillation (OPO) and second-harmonic generation (SHG) in a 7.9 mum periodically poled lithium tantalate (PPLT). The uncoated 15-mm-long PPLT device exhibits a low threshold of 150 mW and a differential slope efficiency of 22.6%, rendering 56 mW blue generation when pumped by a pulsed 532 nm green laser with an average power rating of 400 mW. These observations were attributed to a quasi-phase-matching (QPM) structural design with a 75% domain duty cycle to ensure the concurrence of frequency doubling with the first-order QPM-OPO PPLT device via the second-order QPM-SHG process.
Reflection coefficient of inhomogeneous anisotropic impedance plane
Solved the problem of constructive synthesis of an inhomogeneous anisotropic impedance plane reflecting a homogeneous plane wave in two different preset directions on a matched and cross polarization. Obtained the reflection coefficients and expressions for the scattering diagrams. The impedance is implemented by the frequent array of orthogonal strips. The law of distribution of the reactance was obtained in an explicit form. It is shown that for arbitrarily given (unequal) directions of reflections on matched and cross polarizations, the orientation of the reactance strips turns out to be variable along the plane. Formulated restrictions on class of implemented scattering diagrams. Shown the results of numerical studies.