Nonlinear surface waves on the boundary of a photorefractive crystal

Abstract

The determination of pulsation mode and distance for field Cepheids is a complicated problem best resolved by a luminosity estimate. For illustration a technique based on spectroscopic luminosity discrimination is applied to the 4.47 day s-Cepheid FF Aql. Line ratios in high dispersion spectra of the variable yield values of M V = −3.40 ± 0.02 s.e. (±0.04 s.d.), average effective temperature T eff = 6195 ± 24 K, and intrinsic color ( B − V ) 0 = +0.506±0.007, corresponding to a reddening of E B−V = 0.25 ± 0.01, or E B−V (B0) = 0.26 ± 0.01. The skewed light curve, intrinsic color, and luminosity of FF Aql are consistent with fundamental mode pulsation for a small-amplitude classical Cepheid on the blue side of the instability strip, not a sinusoidal pulsator. A distance of 413 ± 14 pc is estimated from the Cepheid's angular diameter in conjunction with a mean radius of R = 39.0 ± 0.7 R inferred from its luminosity and effective temperature. The dust extinction toward FF Aql is described by a ratio of total-to-selective extinction of R V = A V /E(B − V ) = 3.16 ± 0.34 according to the star's apparent distance modulus.

The surface waves propagating along the contact between the layer with the constant gradient of refractive index and photorefractive crystal

“…Here we describe the extraordinary polarized (p-polarized) nonlinear surface waves Transverse magnetic (TM waves) with the vector of magnetic field strength H = (0, H y , 0) [26][27][28][29][30]. The light intensity in surface wave I ∝ |H y | 2 does not depend on the coordinate y.…”

“…We suppose here that photorefractive crystal is characterized by diffusion mechanism of nonlinearity formation, which describes the nonlinear addition to the unperturbed refractive index of a photorefractive crystal [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. The propagation of light leads to the appearance of an intracrystalline electric field E sc x , which is directed along the optical axis (which coincides with x axis).…”

“…The propagation of light leads to the appearance of an intracrystalline electric field E sc x , which is directed along the optical axis (which coincides with x axis). The intracrystalline electric field changes the refractive index in accordance with the Pockels effect in a linear manner, and the nonlinear addition ∆n P can be written as [26][27][28][29][30]:…”

“…The intracrystalline field E sc x becomes non-linearly dependent on the light intensity in the surface wave because of the action of the diffusion mechanism of the redistribution of photoinduced electric charge carriers in a photorefractive crystal [30]. The authors usually write the intracrystalline field as follows [26][27][28][29][30]:…”

“…Typically, non-linear contacting media are selected [19,20]. It is also studied the waveguide properties of interfaces in metamaterials (left-handed materials) [21][22][23] and photorefractive crystals [24][25][26][27][28][29]. The field-induced change in the refractive index in photorefractive crystals makes it possible to use them in various optical devices [30][31][32][33][34].…”