Tunable Soft-Matter Optofluidic Waveguides Assembled by Light

Brzobohatý, Oto; Chvátal, Lukáš; Jonáš, Alexandr; Šiler, Martin; Kaňka, Jan; Ježek, Jan; Zemánek, Pavel

doi:10.1021/acsphotonics.8b01331

Cited by 19 publications

(11 citation statements)

References 39 publications

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“…At the end, the spatio-temporal variations of refractive index foretells that the UV 254 irradiated toluene, particularly that is irradiated from above, can be operated as a graded index fluidic waveguide 58 – 60 and this will be considered in a future work. Moreover, different characteristics of VOCs have to be explored under different experimental conditions since the experiment is strongly sensitive to the ambient conditions as well as the way of the UV irradiation.…”

Section: Resultsmentioning

confidence: 99%

Spatio-temporal photolysis rate profiles of UV254 irradiated toluene

El-Tawargy

2022

Sci Rep

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The volatile organic compound (VOC) toluene is irradiated with a 254 nm UV source. The studied sample (1 mL) of toluene is equipped in a sealed quartz cuvette and inserted in one of the Michelson interferometer’s arms. During a UV254 irradiation of 1 h, the variation in the toluene’s refractive index profiles are monitored as a movement of Michelson interference fringes. These interferograms are recorded and digitally analyzed to produce their phase map distributions and, hence, reconstructing the refractive index profiles which are expressing the toluene’s photolysis behavior. With increasing the UV254 irradiation time, the toluene’s refractive index profiles exhibit both temporal and spatial decrease due to the production of benzyl radicals and the consequent oxidation of these radicals. The spatio-temporal refractive index and photolysis rate profiles of toluene are reconstructed and discussed.

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Section: Resultsmentioning

confidence: 99%

Spatio-temporal photolysis rate profiles of UV254 irradiated toluene

El-Tawargy

2022

Sci Rep

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“…(5) [Eq. (6)] denotes that the first term depends on the incident electric (magnetic) field while the last two terms are determined by the radiative electric (magnetic) field of the ED and MD in the other particle. Note that the last terms in the second brackets in Eqs.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…The optical binding force is mediated by the momentum exchange between light and matter to realize stable equilibrium configurations of tiny objects [1,2]. Therefore, it is one of the most important tools in light-induced micro/nanoparticle self-assembly of, e.g., arrays [3,4], metamolecule [5], colloid optical waveguide [6], and optical matter [2,7]. In general, there are two forms of the force.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric longitudinal optical binding force between two identical dielectric particles with electric and magnetic dipolar responses

Duan

Bruce

et al. 2022

Phys. Rev. A

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In general, the optical binding force between identical particles is thought to be symmetric. However, we demonstrate analytically a counter-intuitively asymmetric longitudinal optical binding force between two identical electric and magnetic dipolar dielectric particles. This homodimer is confined in two counter-propagating incoherent plane waves along the dimer's axis. The force consists of the electric dipolar, magnetic dipolar, and electricmagnetic dipolar coupling interactions. The combined effect of these interactions is markedly different than the expected behavior in the Rayleigh approximation. The asymmetric force is a result of the asymmetric forward and backward scattering of the particles due to the dipolar hybridization and coupling interactions. Consequently, it leads to a harmonic driving force on the pair, which decays with the interparticle distance to the first power. We show the rich nonequilibrium dynamics of the dimer and of the two particles impelled by the driving and binding forces and discuss the ranges of particle refractive index and size in which the asymmetric binding force arises. Our results open perspectives for nonequilibrium light-driven multiparticle transport and selfassembly.

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“…Nonlinear self-trapping of laser light in soft-matter systems, such as dielectric [ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ] or plasmonic colloids [ 6 ], [ 7 ], [ 8 ], [ 9 ], [ 10 ], [ 11 ], [ 12 ], [ 13 ], [ 14 ], [ 15 ] as well as biological media [ 16 ], [ 17 ], [ 18 ], [ 19 ], [ 20 ], has attracted increased attention over the past decade. The effect is described as diffraction-less propagation of laser light, trapped over many diffraction lengths by virtue of the intensity-dependent nonlinear refractive index of the medium.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear thermal lensing of high repetition rate ultrafast laser light in plasmonic nano-colloids

Agiotis

Meunier

2022

Nanophotonics

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We report on experimental observations of phenomenological self-trapping in plasmonic colloids of varying plasmon peaks in the visible/near infrared. A femtosecond (fs) oscillator is used in both pulsed (35 fs, 76 MHz) and continuous wave (cw) operation for comparison. We show that for both modes and for all examined colloids (and under typically applied external focusing conditions in self-trapping studies in colloidal media) nonlinear propagation is governed by thermal defocusing of the focused beam, which precedes the steady-state regime reached by particle diffusion, even far from the plasmon resonance (or equivalently for non-plasmonic colloids, even for low absorption coefficients). A strategy for the utilization of high repetition fs pulses to mitigate thermal lensing and promote gradient force-induced self-trapping is discussed. Notably, nonlinear thermal lensing is further accompanied by natural convection due to the horizontal configuration of the setup. Under resonant illumination, for both fs and cw cases, we observe mode break-up of the beam profile, most likely due to azimuthal modulation instability. Importantly, time-resolved observations of the break-up indicate that in the fs case, thermal convection heat transfer is reduced in magnitude and significantly decoupled in time from thermal conduction, presumably due to temperature increase confinement near the particles. We anticipate that our findings will trigger interest toward the use of high repetition fs pulses for self-channeling applications in nano-colloids.

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Tunable Soft-Matter Optofluidic Waveguides Assembled by Light

Cited by 19 publications

References 39 publications

Spatio-temporal photolysis rate profiles of UV254 irradiated toluene

Spatio-temporal photolysis rate profiles of UV254 irradiated toluene

Asymmetric longitudinal optical binding force between two identical dielectric particles with electric and magnetic dipolar responses

Nonlinear thermal lensing of high repetition rate ultrafast laser light in plasmonic nano-colloids

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