Frequency conversion of Bessel light beams in nonlinear crystals

Abstract

We present a numerical simulation of the response of an expanding relativistic jet to the ejection of a superluminal component. The simulation has been performed with a relativistic time-dependent hydrodynamical code from which simulated radio maps are computed by integrating the transfer equations for synchrotron radiation. The interaction of the superluminal component with the underlying jet results in the formation of multiple conical shocks behind the main perturbation. These trailing components can be easily distinguished because they appear to be released from the primary superluminal component instead of being ejected from the core. Their oblique nature should also result in distinct polarization properties. Those appearing closer to the core show small apparent motions and a very slow secular decrease in brightness and could be identified as stationary components. Those appearing farther downstream are weaker and can reach superluminal apparent motions. The existence of these trailing components indicates that not all observed components necessarily represent major perturbations at the jet inlet; rather, multiple emission components can be generated by a single disturbance in the jet. While the superluminal component associated with the primary perturbation exhibits a rather stable pattern speed, trailing components have velocities that increase with distance from the core but move at less than the jet speed. The trailing components exhibit motion and structure consistent with the triggering of pinch modes by the superluminal component. The increase in velocity of the trailing components is an indirect consequence of the acceleration of the expanding fluid, which is assumed to be relativistically hot; if observed, such accelerations would therefore favor an electron-positron (as opposed to proton rest mass) dominated jet.

Bessel-like beams with z-dependent cone angles

“…High efficient method for production of Bessel beam can be also based on using anisotropic crystals [10,11].…”

Generation and propagation of high-order Bessel vortices in linear and non-linear crystals

“…The generation of harmonic is fulfilled in conditions of longitudinal synchronism simultaneously along all azimuths within the region of (0÷2π). Due to axial symmetry of interaction the second harmonic field is also Bessel beam with the same cone angle θ s that provides maximum of overlap integral with BLB of fundamental frequency [11]. Note that the analysis of oe-e type interaction is fully analogical.…”

“…The peculiarity of using Bessel light beams for generation of the second harmonic consists, as is known, of necessity of fulfillment the conditions of transverse as well as longitudinal synchronisms (phase-matching) [11,12]. In a case when BLB propagates along the direction of phase-matching for plane waves or Gaussian-type beams, the simultaneous fulfillment of these conditions, strictly speaking, is unrealizable.…”

Self-action of Bessel light beams in cubic gyrotropic photorefractive crystals

“…) Broadening of the Fourier spectrum of a diverging Bessel light beam in the far zone vs. power of side illumination for different beam intensities: 1.2 W (1, 2) and 0.6 W (3, 4), no side illumination(5). b) Changes in the polarization azimuth of a Bessel light beam vs. beam power for a.c. electric field strength 7 kV/cm (1, 1′) and 5 kV/cm (2, 2′), for a d.c. electric field 7 kV/cm(3, 3′).…”

“…Consequently, in order to obtain a Bessel light beam, suitable optical systems are those making it possible to form both a ring-shaped field (an annular aperture, an optical fiber) and a set of plane waves characterized by a cone of wave vectors (hologram, axicon, lens with spherical aberration). The most widely used elements for obtaining a zero-th order Bessel light beam are conical lenses or "axicons" [5]. The angle of refraction in these devices is a constant quantity, which ensures constancy of the convergence angle of the wave vectors of the light beam beyond the axicon.…”