I. I. Naumova

Mapping of periodically poled crystals via spontaneous parametric down-conversion

A new method for characterization of periodically poled crystals is developed based on spontaneous parametric down-conversion. The method is demonstrated on crystals of Y:LiNbO3, Mg:Y:LiNbO3 with non-uniform periodically poled structures, obtained directly under the Czochralski growth procedure and designed for application of 1.064 μmpumped OPO in the mid-infrared range. Infrared dispersion of refractive index, effective working periods and wavelengths of OPO were determined by special treatment of frequency-angular spectra of spontaneous parametric down-conversion in the visible range. Two-dimensional mapping via spontaneous parametric down-conversion is proposed for characterizing spatial distribution of bulk quasi-phase matching efficiency across the input window of a periodically poled sample.

Characterization of aperiodic domain structure in lithium niobate by spontaneous parametric down-conversion spectroscopy

We develop a technique for detailed analysis of aperiodically poled crystalline nonlinear transfer functions. The method allows precise evaluation of 1D aperiodic domain structure amplitude spectra. It also allows determining the angle of periodic poling in respect to the crystalline z axis, as well as the dispersion of both ordinary and extraordinary refractive indexes in a broad spectral range. The measurement is non-destructive, and all data can be extracted from two frequency-angular spontaneous parametric down-conversion (SPDC) spectra. The precision of the domain structure analysis for aperiodically poled lithium niobate is increased by an order of magnitude in comparison to previously reported techniques based on spontaneous parametric down-conversion.

Evaluating the spectral sensitivity of the nonlinear-optical terahertz wave radiation detecors via spontaneous parametric down-conversion spectra

Principal parameters of the nonlinear-optical crystals are analyzed, which govern the spectral sensitivity of the terahertz wave detectors based on the frequency conversion from terahertz to optical range. A method is developed and experimentally demonstrated for characterizing these parameters. The method is founded on the spontaneous parametric down-conversion spectra observation without external terahertz wave radiation.

Simultaneous generation second and third harmonics in crystal with the modulated second-order nonlinearity

We present results of theoretical and experimental study of the consecutive third harmonic generation in a periodically poled bulk LiNbO/sub 3/:Y crystal. It is shown theoretically that under certain conditions for nonlinear coefficients the energy of wave with frequency /spl omega/ in the consecutive considered interaction can be almost completely converted to the energy of wave with frequency 3/spl omega/.