Parametric amplification of light waves at low-frequency pumping in aperiodic nonlinear photonic crystals

Multiple quasi-phase-matching in nonlinear Raman–Nath diffraction

“…3(c), the Fourier transform of the function ηy contains a triplet of primary spatial frequencies, with the Fourier amplitudes ranging from 0.3 to 0.4. These values of the Fourier amplitudes are consistent with the results found in [17]. The spatial frequencies of these peaks are suitable for the compensation for the wave vector mismatch for the first three NRND orders.…”

“…We determine the Fourier amplitudes of these components for the parameters C j 1 and φ j 0. In this case (see also [17]), ηy is given by ηy sgnsinG Y ;0 y sinG Y ;1 y sinG Y;2 y: (6) Figure 3(b) shows the layer thicknesses provided by the function ηy of the layer number in the propagation direction y. The layer thicknesses vary in the range from 8.0 to 12.5 μm, with a mean value of 10.2 μm.…”

Object reconstruction from multiplexed quantum ghost images using reduction technique

“…The required states can be obtained, e. g., in consecutive coupled parametric interactions in nonlinear crystals located either outside [11,12] or inside [13] an optical resonator, in nonlinear waveguide structures [14,15] where modes are coupled through evanescent modes, in a spatially modulated pump beam [16]. The considered GI multiplexing employs four-frequency entangled quantum states formed through parametric decay of pump photons into two photons with different frequencies that are mixed in the same crystal with pump photons, which produces photons with sum frequencies [17,18]. Quantum theory of this process has been systematically developed in recent years [19][20][21][22].…”

“…Naturally, the coefficients 2 , 3 , 4 can be made equal by choice of setup parameters. In addition, in the following formulas (18) and (19) the factors dependent on the measurement unit choice will be omitted for brevity.…”

Improvement of an optical image by the measurement reduction technique at parametric multiplexing

“…As it is well-known, in traditional parametric amplification of an optical image with high-frequency pumping, an additional image appears at the so-called idle frequency (see, for example [1,2]). In the case of processes of optical parametric amplification with low-frequency pumping that can be realized in coupled parametric processes [3][4][5] optical images are formed at more than two frequencies [6][7][8][9][10]. In other words, in coupled parametric interactions frequency multiplexing of optical images occurs.…”