Oscillatory tides flowing over rough topography on the ocean floor generate internal gravity waves, which are a major source of ocean mixing. Linear inviscid theory can describe waves generated by gentle topography with slopes that are less steep than the propagation angle of the internal waves; such topography is termed subcritical. However, a clear physical picture of internal waves generated...

Second-order nonlinear optical diffraction by standing acoustic waves in a crystalline plate is theoretically investigated. A detailed analysis of the polarization state of the second-harmonic light diffracted by both longitudinal and transversal acoustic waves is carried out. It is shown that longitudinal standing acoustic waves only allow p-polarized nonlinear optical diffraction, irrespectiv...

A transplantable frequency selective metasurface element (FSMSE) for high-order harmonic suppression (HS) is presented in this paper. The proposed harmonic free FSMSE can be integrated with arbitrary frequency selective surfaces (FSSs) operating at the same frequency band. The designed HS-FSMSE is applied to two different types of FSSs for verification of harmonic suppression, respectively. One...

We demonstrate phase-matched second harmonic generation in gallium nitride on silicon microdisks. The microdisks are integrated with side-coupling bus waveguides in a two-dimensional photonic circuit. The second harmonic generation is excited with a continuous wave laser in the telecom band. By fabricating a series of microdisks with diameters varying by steps of 8 nm, we obtain a tuning of the...

We study the second-harmonic generation via transversely matched interaction of two counterpropagating ultrashort pulses in chi(2) photonic structures. We show that the emitted second-harmonic wave attains the form of spatially expanding toroid with the initial thickness given by the cross correlation of the pulses. We demonstrate the formation of such toroidal waves in crystals with random fer...

We report on the observation of multiple third-harmonic conical waves generated in an annular periodically poled nonlinear photonic crystal. We show that the conical beams are formed as a result of the cascading effect involving two parametric processes that satisfy either the transverse and/or longitudinal phase-patching conditions. This is the first experimental observation of third-harmonic ...

We theoretically propose a new procedure of designing quasi-phase-matching (QPM) gratings for compressing optical ultra-short pulses during second-harmonic generation. The grating consists of blocks of crystal with same block length and the direction of spontaneous polarization of each block is determined by optimal algorithm, by which the sign of the nonlinear coefficient of each block is opti...

The vertical propagation of nonlinear acoustic waves in an isothermal atmosphere is considered. A new analytical solution that describes a finite-amplitude wave of an arbitrary wavelength is obtained. Although the shortand long-wavelength limits were previously considered separately, the new solution describes both limiting cases within a common framework and provides a straightforward way of i...

The nonlinear self-interaction of an electrostatic surface wave on a semibounded quantum plasma with relativistic degeneracy is investigated by using quantum hydrodynamic (QHD) model and the Poisson’s equation with appropriate boundary conditions. It is shown that a part of the second harmonic generated through self-interaction does not have a true surface wave character but propagates obliquel...

Using beam propagation method calculations, we show that new effects occur for second-harmonic generation in the Cerenkov regime when it is optimized for efficient coupling to leaky modes. The fundamental throughput becomes independent of the input power over a few decades; i.e., optical power limiting is found. At even higher input powers, the fundamental throughput abruptly switches back to a...