Noncollinear Optical Frequency Doubling in Strontium Barium Niobate

Abstract

The observation of a novel noncollinear optical second-harmonic generation mechanism is reported. In strontium barium niobate crystals, a circular cone of second-harmonic light is generated when a fundamental beam of intensive laser light is directed along the crystallographic c axis. It can be shown that the effect is caused by the nonlinear polarization of antiparallel ordered ferroelectric microdomains.

Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

“…The difference in the pulse duration obtained with both methods has not exceeded 2%. This difference is consistent with the resolution error introduced by our experimental setup taking into account the parameters of the CCD camera, the intersection angle α and the propagation errors in the formulas (8) and (9). For the parameters used in our experiment we obtained an error estimation of around 5% for the pulse duration and of the order of 10% for the chirp determination.…”

“…While the reversed orientation of domains corresponds to inversion of sign of the quadratic susceptibility, the refractive index of these crystals remains practically homogeneous [7]. Such crystals provide phase matching for frequency conversion processes over wide angular and frequency bandwidths without need for angular or temperature tuning as it is usual in typically used homogeneous nonlinear crystals [8][9][10]. Phase matching is obtained thanks to the continuous set of reciprocal lattice vectors, G, arising from the random size and distribution of the nonlinear domains, which entails a random distribution of the nonlinearity sign.…”

Random Quasi-Phase-Matched Second Harmonic Generation in Periodically Poled Lithium Tantalate

“…© 2010 Optical Society of America OCIS codes: 190.0190, 190.2620 Parametric wavelength conversion in media with a random nonlinearity, discussed in the pioneering works by Freund [1] and by Dolino and coworkers [2], has recently attracted significant interest due to its nonresonant behavior, i.e., its low sensitivity to phase matching and its broadband response [3][4][5][6][7][8][9]; potential applications have also been investigated, such as the time-domain characterization of femtosecond pulses [10]. Moreover, in connection with quasi-periodicity, a few important aspects of nonlinear wave mixing and transverse phase matching have been unveiled [11][12][13][14]. Broadband frequency conversion can take place in both isotropic polycrystalline ferroelectrics [3] and in crystals with randomly distributed antiparallel ferroelectric micro-domains [5,6]; the former are easily accessible and support a linear trend in terms of the generated second harmonic (SH) versus the input fundamental power, while the latter exhibit the standard quadratic dependence of the generated SH versus the input fundamental power, with higher conversion efficiencies.…”

“…Moreover, in connection with quasi-periodicity, a few important aspects of nonlinear wave mixing and transverse phase matching have been unveiled [11][12][13][14]. Broadband frequency conversion can take place in both isotropic polycrystalline ferroelectrics [3] and in crystals with randomly distributed antiparallel ferroelectric micro-domains [5,6]; the former are easily accessible and support a linear trend in terms of the generated second harmonic (SH) versus the input fundamental power, while the latter exhibit the standard quadratic dependence of the generated SH versus the input fundamental power, with higher conversion efficiencies.…”

“…The presence of antiparallel ferroelectric domains can intrinsically depend on the specific growth technique, as is the case for strontium barium niobate (SBN, d 33 = 12 pm/V) [4]. Here, a random domain distribution is generated during boule preparation [7,11]. In SBN and with reference to SH generation, Horowitz and coworkers studied the role of microdomains superimposed to an ordered pattern [6].…”