Self-Trapping of “Necklace” Beams in Self-Focusing Kerr Media

Soljačić, Marin; Sears, Suzanne M.; Segev, Mordechai

doi:10.1103/physrevlett.81.4851

Cited by 171 publications

(110 citation statements)

References 17 publications

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“…The central result is that the information coded in the input array of topological charges is transformed into a predefined set of stable, robust, and neat bright soliton spots. We also notice that our results pave the way for generating controllable necklace beams 6 with multicolor solitons. …”

supporting

confidence: 52%

Controllable Patterns of Parametric Solitons

Minardi

Molina‐Terriza

Bramati

et al. 2001

Optics & Photonics News

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Optical vortices are dark holes nested in light beams that feature a helical phase-ramp around a core where the light intensity vanishes. 1 The phase of the field changes by 2m (m being an integer called the topological charge of the vortex) along any closed loop around the vortex core. Vortices abound in nature and thus appear spontaneously in many optical settings. They can be also generated, e.g., by appropriate phase masks. Because of their helical phase front, light beams with nested vortices can be used in specialized optical tools with far-reaching applications, such as optical tweezers and spanners. Similarly, in soliton systems, such a helical phasefront opens the door to unique possibilities.Multicolor solitons, 2 which are formed by the mutual trapping of multifrequency light beams, provide the ideal laboratory for exploring such possibilities. In the process of second-harmonic (SH) generation, intense light beams with nested vortices self-split into sets of spatial solitons. The question was whether the number of output solitons could be controlled, e.g., by the value of the topological charges m , m 2 of the input fundamental frequency (FF) and of the SH input signals. When only the FF light beam is input in the crystal, the SH beam is generated with the topological charge m 2 = 2m and the beams were observed to self-split into a certain number of solitons because of a spontaneous modulational instability.3 In a different scenario, however, one in which a coherent second-harmonic seed is present at the input together with the fundamental beams, and in which the topological charges of the input light signals are chosen to verify m 2 ≠ 2m , the number of output solitons was predicted to be n=|2m -m 2 |. This rule is dictated by the different dynamics experienced by the different azimuthal portions of the beams. 4 We have recently observed experimentally in a lithium triborate crystal that the possibility of generating the above mentioned patterns of solitons in a controllable way actually holds. 5 The experiment consisted in focusing 1.1-psec pulses from a mode-locked Nd:glass laser onto a spot of approximately 50 m in a 3-cm-long crystal cut for type I non-critical phasematching, under conditions of seeded second-harmonic generation pumped at 1055 nm. We prepared FF pump and SH seed signals separately by splitting the laser pulses over two different beam-shaping lines. A vortex of different topological charge in each line was nested into the beams by using high-diffraction-efficiency computer-generated holograms. The two beams were joined, aligned collinearly and coaxially, phase-delayed, and focused at the crystal. Figure 1 shows the salient point of the experimental observations. At low input intensities [see Fig. 1 (a)], the vortices experience diffraction and spread. Nevertheless, when the input power is increased above a threshold, a controllable number of solitons is observed [see Figs. 1 (c)- (d)]. In the images shown, three, four, and five clean solitons were respectively harvested, depending...

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supporting

confidence: 52%

Controllable Patterns of Parametric Solitons

Minardi

Molina‐Terriza

Bramati

et al. 2001

Optics & Photonics News

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“…Recently, very interesting soliton structure in the form of azimuthally periodically modulated beams ("necklace beams") was reported in [2,3]. Self-trapped necklace beams can exist in a homogeneous bulk NL optical medium, exhibiting quasi-stable expansion even in a self-focusing NL medium [2][3][4].…”

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confidence: 99%

"Necklace-Ring" Beams in Saturable Kerr Media with Square-Root Nonlinearity

Petrović

2007

Acta Phys. Pol. A

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“…We further show that this transition, accompanied by a peak in the collapse distance, can be exploited to control and manipulate the collapse dynamics of two coupled beams. Our results shed light on the basic nonlinear interaction between self-focused collapsing beams and are applicable in different scenarios, including that of multiple filamentation and collapse of complex multilobe beams such as necklace beams [25].To investigate the propagation and collapse of two spatially separated beams in Kerr media, we numerically integrate the scalar (2+1)D nonlinear Schrödinger equation (NLSE), neglecting dispersion and high-order terms. These assumptions are reasonable as long as the dispersion length is longer than the nonlinear and diffraction length scales.…”

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confidence: 99%

Self-focusing dynamics of coupled optical beams

et al. 2007

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We theoretically and experimentally investigate the mutual collapse dynamics of two spatially separated optical beams in a Kerr medium. Depending on the initial power, beam separation, and the relative phase, we observe repulsion or attraction, which in the latter case reveals a sharp transition to a single collapsing beam. This transition to fusion of the beams is accompanied by an increase in the collapse distance, indicating the effect of the nonlinear coupling on the individual collapse dynamics. Our results shed light on the basic nonlinear interaction between self-focused beams and provide a mechanism to control the collapse dynamics of such beams. [5]. Over the past decade, with the advent of high peak power ultra-short pulsed lasers, self-focusing dynamics of optical beams have revealed a remarkable richness of spatial and temporal nonlinear phenomena. These include observation of the universal self-similar spatial collapse profile known as the Townes profile [6], multiple filamentation [7], self steepening and pulse splitting [8,9], multiphoton ionization, and supercontinuum generation [9,10], along with saturation and plasma generation that typically arrest the collapse [11].Related optical beam interactions within the context of spatial solitons [12,13] have drawn considerable interest in recent years. Spatial solitons in 1D Kerr media are shown to interact in a particle-like elastic manner, where the number of solitons and the corresponding directions and propagation velocities are conserved [12,14]. Depending on the relative phase, attractive and repulsive forces and power transfer are observed between interacting solitons [15]. In saturable nonlinear media, which can support (2+1)D solitons, phenomena such as soliton fusion, fission, annihilation, and spiraling occur [16,17,18,19]. The interaction between incoherent solitons, where the medium responds non-instantaneously, exhibits similar effects as those observed with coherent solitons in nonlinear saturable media [20].In the regime of optical beam collapse in a Kerr medium, where self focusing is dominant and beams do not maintain their spatial distribution, only a few theoretical studies of beam interactions have been reported [21,22,23,24], and to the best of our knowledge no experiments have been performed. While in these initial theoretical studies several qualitative trends, such as repulsion, attraction, and fusion of two beams, were identified, the detailed dynamics and the transition to fusion of two beams, especially when each beam has a power near P cr , has not been explored.In this Letter, we investigate both theoretically and experimentally the spatial collapse dynamics of two coherently coupled beams in Kerr media. We observe repulsion and attraction between the collapsing beams, and a sharp transition to fusion of the beams, which is dependent on their initial power, spatial separation and relative phase. We further show that this transition, accompanied by a peak in the collapse distance, can be exploited to control and manipulat...

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Self-Trapping of “Necklace” Beams in Self-Focusing Kerr Media

Cited by 171 publications

References 17 publications

Controllable Patterns of Parametric Solitons

Controllable Patterns of Parametric Solitons

"Necklace-Ring" Beams in Saturable Kerr Media with Square-Root Nonlinearity

Self-focusing dynamics of coupled optical beams

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