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Derrien T.J.-Y.,BAM Federal Institute of Materials Research and Testing | Kruger J.,BAM Federal Institute of Materials Research and Testing | Itina T.E.,CNRS Hubert Curien Laboratory | Hohm S.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie Mbi | And 2 more authors.
Optics Express | Year: 2013

The formation of near-wavelength laser-induced periodic surface structures (LIPSS) on silicon upon irradiation with sequences of Ti:sapphire femtosecond laser pulse pairs (pulse duration 150 fs, central wavelength 800 nm) is studied theoretically. For this purpose, the nonlinear generation of conduction band electrons in silicon and their relaxation is numerically calculated using a two-temperature model approach including intrapulse changes of optical properties, transport, diffusion and recombination effects. Following the idea that surface plasmon polaritons (SPP) can be excited when the material turns from semiconducting to metallic state, the "SPP active area" is calculated as function of fluence and double-pulse delay up to several picoseconds and compared to the experimentally observed rippled surface areas. Evidence is presented that multi-photon absorption explains the large increase of the rippled area for temporally overlapping pulses. For longer double-pulse delays, relevant relaxation processes are identified. The results demonstrate that femtosecond LIPSS on silicon are caused by the excitation of SPP and can be controlled by temporal pulse shaping. © 2013 Optical Society of America. Source


Hohm S.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie Mbi | Rosenfeld A.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie Mbi | Kruger J.,BAM Federal Institute of Materials Research and Testing | Bonse J.,BAM Federal Institute of Materials Research and Testing
Applied Physics Letters | Year: 2013

The formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration, 800 nm center wavelength) is studied experimentally using a transillumination femtosecond time-resolved (0.1 ps-1 ns) pump-probe diffraction approach. This allows to reveal the generation dynamics of near-wavelength- sized LIPSS showing a transient diffraction at specific spatial frequencies even before a corresponding permanent surface relief was observed. The results confirm that the ultrafast energy deposition to the materials surface plays a key role and triggers subsequent physical mechanisms such as carrier scattering into self-trapped excitons. © 2013 American Institute of Physics. Source


Hohm S.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie Mbi | Rosenfeld A.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie Mbi | Kruger J.,BAM Federal Institute of Materials Research and Testing | Bonse J.,BAM Federal Institute of Materials Research and Testing
Journal of Applied Physics | Year: 2012

The formation of laser-induced periodic surface structures (LIPSS) on two different silica polymorphs (single-crystalline synthetic quartz and commercial fused silica glass) upon irradiation in air with multiple linearly polarized single- and double-fs-laser pulse sequences (τ 150 fs pulse duration, λ 800 nm center wavelength, temporal pulse separation Δt 40 ps) is studied experimentally and theoretically. Two distinct types of fs-LIPSS [so-called low-spatial-frequency LIPSS (LSFL) and high-spatial-frequency LIPSS (HSFL)] with different spatial periods and orientations were identified. Their appearance was characterized with respect to the experimental parameters peak laser fluence and number of laser pulses per spot. Additionally, the dynamics of the LIPSS formation was addressed in complementary double-fs-pulse experiments with varying delays, revealing a characteristic change of the LSFL periods. The experimental results are interpreted on the basis of a Sipe-Drude model considering the carrier dependence of the optical properties of fs-laser excited silica. This new approach provides an explanation of the LSFL orientation parallel to the laser beam polarisation in silica-as opposed to the behaviour of most other materials. © 2012 American Institute of Physics. Source


Hohm S.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie Mbi | Rosenfeld A.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie Mbi | Kruger J.,BAM Federal Institute of Materials Research and Testing | Bonse J.,BAM Federal Institute of Materials Research and Testing
Applied Surface Science | Year: 2013

The formation of laser-induced periodic surface structures upon irradiation of titanium, silicon, and fused silica with multiple irradiation sequences consisting of parallel polarized Ti:sapphire femtosecond laser pulse pairs (pulse duration 50-150 fs, central wavelength ∼800 nm) is studied experimentally. The temporal delay between the individual near-equal energy fs-laser pulses was varied between 0 and 5 ps with a temporal resolution of better than 0.2 ps. The surface morphology of the irradiated surface areas is characterized by means of scanning electron microscopy (SEM). In all materials a decrease of the rippled surface area is observed for increasing delays. The characteristic delay decay scale is quantified and related to material dependent excitation and energy relaxation processes. © 2012 Elsevier B.V. Source


Hohm S.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie Mbi | Rosenfeld A.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie Mbi | Kruger J.,BAM Federal Institute of Materials Research and Testing | Bonse J.,BAM Federal Institute of Materials Research and Testing
Optics Express | Year: 2015

Single- and two-color double-fs-pulse experiments were performed on titanium to study the dynamics of the formation of laserinduced periodic surface structures (LIPSS). A Mach-Zehnder interferometer generated polarization controlled (parallel or cross-polarized) double-pulse sequences in two configurations - either at 800 nm only, or at 400 and 800 nm wavelengths. The inter-pulse delays of the individual 50-fs pulses ranged up to some tens of picoseconds. Multiple of these single- or two-color double-fs-pulse sequences were collinearly focused by a spherical mirror to the sample surface. In both experimental configurations, the peak fluence of each individual pulse was kept below its respective ablation threshold and only the joint action of both pulses lead to the formation of LIPSS. Their resulting characteristics were analyzed by scanning electron microscopy and the periods were quantified by Fourier analyses. The LIPSS periods along with the orientation allow a clear identification of the pulse which dominates the energy coupling to the material. A plasmonic model successfully explains the delay-dependence of the LIPSS on titanium and confirms the importance of the ultrafast energy deposition stage for LIPSS formation. © 2015 Optical Society of America. Source

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