High localization, focal depth and contrast by means of nonlinear Bessel beams

Abstract

We show an experimental and computational comparison between the resolution power, the contrast and the focal depth of a nonlinearly propagated diffraction-free beam and of other beams (a linear and a nonlinearly propagated Gaussian pulse): launching a nondiffractive Bessel pulse in a solution of Coumarine 120 in methanol creates a high contrast, 40 mm long, 10 microm width fluorescence channel excited by 3-photon absorption process. This fluorescence channel exhibits the same contrast and resolution of a tightly focused Gaussian pulse, but reaches a focal depth that outclasses by orders of magnitude that reached by an equivalent Gaussian pulse.

Femtosecond filamentation in transparent media

“…However, preliminary experimental and numerical results have shown that high localization, focal depth and contrast can be achieved by generating a filament from a high power Bessel beams (Polesana et al, 2005). For instance, Polesana et al (2006) have investigated the reshaping of ultrashort pulsed Bessel beams undergoing filamentation in Kerr media.…”

Nonlinear localization of light

“…Because of very local ionization within transparent materials, light filaments readily produce single shot longitudinal illumination and introduce permanent volumetric refractive index change in transparent bulk media for designing optical waveguides and photonic structures [63]. More recently, high resolution, high focal depth, and high contrast fluorescence channels excited by means of three-photon absorption of Coumarine 120 dye in methanol with Bessel beams has been demonstrated offering new applications in multiphoton microscopy [64].…”

Extension of filament propagation in water with Bessel-Gaussian beams

“…The self-reconstruction properties of filaments and their extension were also explained in terms of the energy reservoir surrounding filaments. 16 Nonlinear dynamics of pulsed Bessel beams [17][18][19] and possible applications [20][21][22] were also investigated.…”