Colored conical emission by means of second-harmonic generation

Trillo, Stefano; Conti, Claudio; Trapani, P. Di; Jedrkiewicz, O.; Trull, J.; Valiulis, G.; Bellanca, Gaetano

doi:10.1364/ol.27.001451

Cited by 58 publications

(29 citation statements)

References 16 publications

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“…Again, since no theory has yet been developed for the MI of a bulk solitary beam, we must rely on the study of the MI of the FH+SH planeand-monochromatic eigenmode for disclosing the mechanism of the ST interplay. Indeed, in this case too the MI has been shown to lead to the spontaneous formation of angular dispersion, its gain curve having an X-type profile in the ST frequency domain [15].…”

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confidence: 91%

Red Solitons: Evidence of Spatiotemporal Instability inχ(2)Spatial Soliton Dynamics

Minardi

Blasi

et al. 2003

Phys. Rev. Lett.

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In χ (2) three-wave mixing, the noise-seeded spatio-temporal modulational instability has a dramatic impact on the spatial-soliton dynamics, leading to the counterintuitive observation of a soliton with no apparent participation of the high-frequency field in the process.Optical spatial solitons [1] are ideally monochromatic light beams whose linear diffractive spreading is compensated by a suitable non-linear phase shift. In χ (2) threewave mixing, multi-color solitary beams are sustained by energy exchange among the three waves, whose phasevelocity and wavefront-curvature mismatch give rise to an intensity-dependent phase accumulation [2]. Since their first observation in a second-harmonic generation (SHG) scheme [3], χ (2) spatial solitons have been investigated in a number of different experimental conditions, i.e., in up and down conversion, in bulk, waveguides and periodically-poled crystals, with gaussian and vortex-type pumps; their unique steering, addressing and switching properties have been studied in great detail for potential applications in all-optical interconnects (see reference [4] for an updated review on the topic).With the exception of two recent experiments, where fairly short pulses and long samples were used [5,6], all the above mentioned phenomenology has been investigated in conditions in which material chromatic dispersion was assumed to play a negligible role. However, no matter how long the input pulses are (i.e., how narrow the input pulse spectra are), one should expect appreciable frequency broadening to occur, due the effect of the noise-seeded modulational instability (MI) [7]. In the spatial domain, sizeable MI impact has already been shown to cause spatial filamentation of the SHG-generated temporal soliton, for operation just above threshold [8]. By analogy, one would expect temporal pulse fragmentation to affect the spatial-soliton regime. This process is, however, difficult to detect directly since it would require ultra-high temporal resolution in singleshot acquisition mode.In this paper we present the first evidence for the effect of noise-seeded spatio-temporal (ST) MI on χ (2) spatialsoliton dynamics, which we predict to cause a temporal breakup on the 10-fs scale. We claim ST MI to be the mechanism that explains our counter-intuitive observation of a spatial soliton for which self-trapping only occurs between the low-frequency waves (e.g., the signal and idler), with no apparent participation of the highfrequency wave (e.g., the pump). This is the reason we use the term "red soliton" to indicate such a process even though, strictly speaking, no solitons are formed.Our first experiment was performed in the regime of optical parametric amplification (OPA) of the vacuumstate fluctuations, with the usual scheme assumed to lead to spatial-soliton formation [9]: a pump pulse (527 nm, 1.3 ps, 32 µm spot FWHM) was launched on the input face of a 15 mm-long lithium triborate (LBO) crystal, operated in non-critical, type-I phase matching. For the given pump frequency (Ω p ), w...

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confidence: 91%

Red Solitons: Evidence of Spatiotemporal Instability inχ(2)Spatial Soliton Dynamics

Minardi

Blasi

et al. 2003

Phys. Rev. Lett.

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“…The nonlinear X waves are weakly localized nondiffracting and nondispersing wave packets characterized by a nonseparable spatiotemporal profile (propagation invariant solutions) [31,32], accessible in the normal group-velocity dispersion regime, the formation of which is triggered by conical emission [33]. In [34], it was theoretically demonstrated that an X wave at SH can be generated spontaneously by doubling a broad FH pump beam in the undepleted stage of its propagation.…”

Section: Introductionmentioning

confidence: 99%

Propagation dynamics and X-pulse formation in phase-mismatched second-harmonic generation

et al. 2011

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This paper concerns the theoretical, numerical, and experimental study of the second-harmonic-generation (SHG) process under conditions of phase and group-velocity mismatch and aims to demonstrate the dimensionality transition of the SHG process caused by the change of the fundamental wave diameter. We show that SHG from a narrow fundamental beam leads to the spontaneous self-phase-matching process with, in addition, the appearance of angular dispersion for the off-axis frequency components generated. The angular dispersion sustains the formation of the short X pulse in the second harmonic (SH) and is recognized as three-dimensional (3D) dynamics. On the contrary, the large-diameter fundamental beam reduces the number of the degrees of freedom, does not allow the generation of the angular dispersion, and maintains the so-called one-dimensional (1D) SHG dynamics, where the self-phase-matching appears just for axial components and is accompanied by the shrinking of the SH temporal bandwidth, and sustains a long SH pulse formation. The transition from long SH pulse generation typical of the 1D dynamics to the short 3D X pulse is illustrated numerically and experimentally by changing the conditions from the self-defocusing to the self-focusing regime by simply tuning the phase mismatch. The numerical and experimental verification of the analytical results are also presented.

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“…The above mentioned experimental and theoretical results have stimulated further investigations on the role of Xwaves in nonlinear processes, as well as their description in terms of linear waves with a convenient envelope approach, [12,13,14,15,16,17,18,19,20,21,22,23] and their extension to quantized fields. [24] Within the active field of optical self-invariant pulsed beams (see among others [25,26,27,28,29,30,31]), it was recognized that X-waves may play a fundamental role in all the nonlinear processes encompassing spatio-temporal mechanics, well beyond the realm of quadratic frequency mixing where they had been originally observed.…”

Section: Introductionmentioning

confidence: 99%

Generation and nonlinear dynamics of X waves of the Schrödinger equation

Conti¹

2004

Phys. Rev. E

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The generation of finite energy packets of X-waves is analysed in normally dispersive cubic media by using an X-wave expansion. The 3D nonlinear Schroedinger model is reduced to a 1D equation with anomalous dispersion. Pulse splitting and beam replenishment as observed in experiments with water and Kerr media are explained in terms of a higher order breathing soliton. The results presented also hold in periodic media and Bose-condensed gases.

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Colored conical emission by means of second-harmonic generation

Cited by 58 publications

References 16 publications

Red Solitons: Evidence of Spatiotemporal Instability inχ(2)Spatial Soliton Dynamics

Red Solitons: Evidence of Spatiotemporal Instability inχ(2)Spatial Soliton Dynamics

Propagation dynamics and X-pulse formation in phase-mismatched second-harmonic generation

Generation and nonlinear dynamics of X waves of the Schrödinger equation

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