Abstract
We show that spatiotemporal light bullets generated by self-focusing and filamentation of 100 fs, 1.8 μm pulses in a dielectric medium with anomalous group velocity dispersion (sapphire) are extremely robust to external perturbations. We present the experimental results supported by the numerical simulations that demonstrate complete spatiotemporal self-reconstruction of the light bullet after hitting an obstacle, which blocks its intense core carrying the self-compressed pulse, in nonlinear as well as in linear (free-space) propagation regimes.
Highlights
Filamentation of intense femtosecond laser pulses in transparent dielectric media exhibit universal features, such as long range propagation, which produces a narrow plasma channel, selfcleaning and robustness of the spatial mode, complex temporal dynamics, such as shock front generation, pulse splitting and compression, and supercontinuum generation accompanied by colored conical emission [1]
We show that spatiotemporal light bullets generated by selffocusing and filamentation of 100 fs, 1.8 μm pulses in a dielectric medium with anomalous group velocity dispersion are extremely robust to external perturbations
Pcr = 0.15λ 2/n0n2 = 10 MW is the critical power for self-focusing in sapphire, where λ is wavelength, n0 and n2 are linear and nonlinear refractive indexes, respectively), the light bullet composed of a narrow intense central core of 18 μm FWHM diameter, which carries the self-compressed pulse of 38 fs duration, surrounded by an extended ring-shaped spatiotemporal periphery, emerged after the nonlinear focus at z ≈ 6 mm of propagation
Summary
Filamentation of intense femtosecond laser pulses in transparent dielectric media exhibit universal features, such as long range propagation, which produces a narrow plasma channel, selfcleaning and robustness of the spatial mode, complex temporal dynamics, such as shock front generation, pulse splitting and compression, and supercontinuum generation accompanied by colored conical emission [1]. Strong coupling between the core and periphery arises from the interplay between nonlinear losses (multiphoton absorption and ionization), self-focusing and diffraction, resulting in reshaping of the Gaussian input beam into a Bessel-like beam [2, 3]; the sub-diffractive propagation of the central core, which carries an ultrashort pulse, is structurally sustained by the conical energy flux from the periphery [4]. Numerical simulations suggest that light filaments carrying few-optical cycle pulses are able to reconstruct their temporal structure when propagating in the medium with huge discontinuity of nonlinear properties, such as gas-glass-gas interface [15]. It is worth mentioning that selfhealing (self-reconstruction) is an intrinsic property of linear conical waves, e.g. Bessel [21] and Airy [22] beams and Bessel X-waves [23] owing to their transverse energy flux
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