Surface sum-frequency generation from chiral medium by elliptically polarized light beyond plane-wave approximation and coplanar geometry of incidence

Aiming to study the nonlinear response of the surface of isotropic chiral medium, we obtained analytical expression relating the transverse amplitudes of the spatial Fourier-spectra of two incident arbitrary polarized fundamental beams and one signal reflected beam at the sum-frequency within the first-order approximation by their divergence angles. The calculations, carried out in paraxial approximation, simultaneously take into account the spatial dispersion of the bulk of the medium, its near-surface heterogeneity and the transverse finiteness of the three interacting light beams with arbitrary amplitude profiles and orientation in space. A special compact form for the final formulas was found, which makes use of effective nonlinear transformation tensors, the components of which are solely determined by the geometry of incidence of the beams and the material constants of the medium. A possibility of ``switching off'' the certain mechanisms of nonlinear response by choosing the specific polarization states of the incident beams is discussed.

Nonlinear dynamics in the Jupiter magnetosphere: implications of dust-acoustic cnoidal mode

Different types of waves and their nature in the Jovian middle magnetosphere are still not clear or specified. For this purpose, a generalized hydrodynamic model for an arbitrary amplitude dust-acoustic waves is built for true Jovian magnetosphere. The plasma system consists of positive dust grains, Maxwellian ions and electrons. An evolution equation containing a Sagdeev potential is derived, and its numerical analysis is presented. Unexpectedly, the given data yielded cnoidal waves only with positive potential. The effect of the external magnetic field, Mach number, and directional cosine parameters are studied and manipulated. We think that the present results are important in realizing the main waves in the Jovian magnetosphere, and the possible correlation to its particlesístability and pole acoustic waves.

Acoustic Focusing with Intensity Modulation Based on Sub-Wavelength Waveguide Array

Acoustic focusing with intensity modulation plays an important role in biomedical and life sciences. In this work, we propose a new approach for simultaneous phase and amplitude manipulation in sub-wavelength coupled resonant units, which has not been reported so far. Based on the equivalent impedance and refractive index modulation induced by the change of geometry, arbitrary amplitude response from 0 to 1 and phase shift from 0 to 2π is realized. Thus, the acoustic focusing with intensity modulation can be achieved via waveguide array. Herein, the focal length can be adjusted by alternating the length of supercell, and the whole system can work in a broadband of 0.872f0–1.075f0. By introducing the coding method, the thermal viscosity loss is reduced, and the wavefront modulation can be more accurate. Compared with previous works, our approach has the advantages of simple design and broadband response, which may have promising applications in acoustic communication, non-destructive testing, and acoustic holography.

Arbitrary amplitude ion acoustic solitons, double layers and supersolitons in a collisionless magnetized plasma consisting of non-thermal and isothermal electrons

Using Sagdeev pseudo-potential technique, we have studied the arbitrary amplitude ion acoustic solitons, double layers and supersolitons in a collisionless plasma consisting of adiabatic warm ions, non-thermal hot electrons and isothermal cold electrons immersed in an external uniform static magnetic field. We have used the phase portraits of the dynamical system describing the non-linear behaviour of ion acoustic waves to confirm the existence of different solitary structures. We have found that the system supports (a) positive potential solitons, (b) negative potential solitons, (c) coexistence of both positive and negative potential solitons, (d) negative potential double layers, (e) negative potential supersolitons and (f) positive potential supersolitons. Again, we have seen that the amplitude of the positive potential solitons decreases or increases with increasing n ch according to whether 0 < n c h < n c h ( c ) $0{< }{n}_{ch}{< }{n}_{ch}^{\left(c\right)}$ or n c h ( c ) < n c h ≤ 1 ${n}_{ch}^{\left(c\right)}{< }{n}_{ch}\le 1$ , where n c h ${n}_{ch}$ is the ratio of isothermal cold and non-thermal hot electron number densities, and n c h ( c ) ${n}_{ch}^{\left(c\right)}$ is a critical value of n ch . Also, we have seen that the amplitude of the positive potential solitons decreases with increasing β e , where β e is the non-thermal parameter. We have also investigated the transition of different negative potential solitary structures: negative potential soliton (before the formation of negative potential double layer) → negative potential double layer → negative potential supersoliton → negative potential soliton (after the formation of negative potential double layer) by considering the variation of θ only, where θ is angle between the direction of the external uniform static magnetic field and the direction of propagation of the ion acoustic wave.