Although ultrafast laser materials processing has advanced at a breakneck pace over the last two decades, most applications have been developed with pulses near-IR or visible wavelengths. Recent progress in mid-infrared (MIR) femtosecond source development may create novel capabilities for material processing. This is because, high intensities required such processing, wavelength tuning to longer wavelengths opens pathway special regime of laser-solid interactions. Under these conditions,...

Laser induced periodic surface structures (LIPSS or ripples) were generated on single crystal germanium after irradiation with multiple 3 µm femtosecond laser pulses at a 45° angle of incidence. High and low spatial frequency LIPSS (HSFL LSFL, respectively) observed for both s- p-polarized light. The measured LSFL period light was consistent the currently established origination model coupling between plasmon polaritons (SPP) incident pulses. A vector SPP is introduced to explain formation...

A systematic study of few-cycle pulse laser induced damage threshold (LIDT) determination was performed for commercially-available ultra-broadband optics, (i.e. chirped mirrors, silver beamsplitters, etc.) in vacuum and air, single multi-pulse regime (S-on-1). Multi-pulse morphology at fluences below the single-pulse LIDT studied order to investigate mechanisms leading onset damage. Stark morphological contrast observed between sites formed air versus those vacuum. One effect testing...

Time-resolved diffraction microscopy technique has been used to observe the formation of laser-induced periodic surface structures (LIPSS) from interaction a single femtosecond laser pulse (pump) with nano-scale groove mechanically formed on single-crystal Cu substrate. The dynamics (0-1200 ps) was captured by diffracting time-delayed, frequency-doubled (probe) nascent LIPSS induced pump an infinity-conjugate setup. ripples are observed form asynchronously, first one forming after 50 ps and...

Femtosecond laser-induced damage and ablation (fs-LIDA) is a rich field in extreme non-perturbative nonlinear optics with wide ranging applications, including laser micro- nano-machining, waveguide writing, eye surgery. Our understanding of fs-LIDA, however, limited mostly to visible near-infrared wavelengths. In this work, we systematically study single-shot, fs-laser (fs-LIA) single-crystal germanium from near- mid-infrared wavelengths, compare the fs-LIA wavelength scaling two widely used...

Abstract Potassium dihydrogen phosphate (KDP) and its deuterated analog (DKDP) are unique nonlinear optical materials for high power laser systems. They used widely frequency conversion polarization control by virtue of the ability to grow optical-quality crystals at apertures suitable fusion-class Existing methods freeform figuring KDP/DKDP optics do not produce surfaces with sufficient laser-induced–damage thresholds (LIDT’s) operation in ultraviolet portion high-peak-power In this work,...

Rapid growth and ultra-precision machining of large-size KDP (KH2PO4) crystals with high laser damage resistance are tough challenges in the development large systems. It is interest practical significance to have theoretical models for scientists manufacturers determine laser-induced threshold (LIDT) actually prepared optics. Here, we numerically experimentally investigate on ultra-short pulse regime. On basis rate equation free electron generation, a model dedicated predicting LIDT...

The response of model contamination particles located on the surface a multilayer dielectric mirror when exposed to 1053 nm laser pulses 10 ps or 0.6 duration is investigated. Four different particle types were studied: stainless steel, borosilicate glass, polyethylene, and polytetrafluoroethylene, all having an average diameter about 40 μm. Irradiation with one pulse caused eject from onset fluence in range 5× 100×, depending type, below particle-free, laser-induced damage threshold mirror....

We report on the generation of harmonic-like photon upconversion in a LiNbO3-based nonlinear photonic crystal by mid-infrared (MIR) femtosecond laser pulses. study below bandgap harmonics various driver wavelengths, reaching up to 11th order at 4 μm with 13% efficiency. compare our results numerical simulations based two mechanisms: cascade three-wave mixing and non-perturbative harmonic generation, both which include quasi-phase matching. The model reproduces well general features observed...

Formation of high spatial frequency laser induced periodic surface structures (HSFL) in germanium by 90 fs mid-IR pulses at a 1 kHz repetition rate with wavelengths between λ = 2 and 3.6 μm was studied varying angle incidence polarization. The period these varied from λ/3 to λ/8. A modified surface-scattering model including Drude excitation the optical Kerr effect explains scaling HSFL across wavelengths. Transmission electron microscopy shows presence 30 nm amorphous layer above structure...

Monolayers containing subnanometer striations of silica and hafnia to form composite materials at varying ratios are explored as a method develop high-index dielectric layers with increased laser-induced–damage thresholds (LIDTs). These can then be used in multilayer coatings for short-pulse, high-peak-power laser applications, particularly regions the highest electric-field intensity. Fabrication is achieved by means exposure two different evaporant vapor plumes, where local each plume...

Broadband low dispersion mirrors are fluence-limiting and pulse-shape-limiting components in short pulse lasers. To better understand the current technology state of broadband mirrors, a laser damage competition was held at 2015 Laser Damage Conference. Participants were asked to submit that met minimum reflection 99.5% 45 degrees incidence angle "P" polarization with Group Dispersion Delay (GDD) <± 100 fs² over spectral range 773 nm ± 50 nm. The participants selected coating...

Abstract We investigate the damage resistance of saturated and unsaturated liquid crystals (LC’s) under a wide range laser excitation conditions, including 1053-nm pulse durations between 600 fs 1.5 ns nanosecond at 351 nm 532 nm. This study explores relationship LC’s to laser-induced breakdown (damage) electronic structure ( π -electron delocalization) constituent molecules. The threshold all wavelengths was consistently higher in materials than their counterparts. wavelength’s dependence...

The interactions of microparticles different materials located on the surface a multilayer dielectric mirror with intense 1053-nm laser pulses varying fluence and duration (10 0.6 ps) are investigated. particles caused localized intensification electric field, which becomes dominant mechanism for onset damage secondary contamination at fluences far below pristine (without particles) laser-induced-damage threshold mirror. Several interaction mechanisms leading to material modification...

This broadband, low dispersion mirror damage competition is a continuation of last year's test with 150 ps pulse length results published in 2015 and 40 fs this study. allows direct laser resistance comparison between durations because the samples were tested under identical conditions. The requirements coatings are minimum reflection 99.5% at 45 degrees incidence angle "P" polarization Group Delay Dispersion (GDD) < ± 100 fs² over spectral range 773 nm 50 nm. choice...

A laser pulse impinging on the surface of an optical component can interact with particles, such as contamination debris, to produce a scattered electric field, which, either by itself or combined incident coherently significantly increase local field intensity. This effect be critical importance it reduce laser-induced–damage threshold affected component. In this work, we use field-propagation code improve understanding regarding factors that determine magnitude and location electric-field...

Interactions of liquid crystals (LC's) with polarized light have been studied widely and spawned numerous device applications, including the fabrication optical elements for high-power large-aperture laser systems. Currently, little is known about both effect incident polarization state on laser-induced-damage threshold (LIDT) laser-induced functional (LIFT) behavior at sub-LIDT fluences under multipulse irradiation conditions. This work reports first study nanosecond-pulsed LIDT's...

For laser direct-drive (LDD) fusion implosions, intense beams are used to directly illuminate the inertial confinement (ICF) capsule. The beams' intensity nonuniformity (due speckles) on target can impose perturbation seeds which subsequently amplified by Rayleigh-Taylor instability growth, thereby leading degradation of ICF implosion performance. To devise methods mitigate this issue, adequate understanding underlying so-called laser-imprinting process is required. Here, we report...

Laser solid interaction with < 100 fs pulses from 800 - 3600 nm wavelength was studied at 45 degree angle of incidence s- and p-polarized light. Mid-IR femtosecond laser damage thresholds Si, Ge, ZnSe were determined. Obtained results compared against existing Two Temperature Model for which shown to fail longer wavelengths. Experimental evidence suggests that electron dynamics the vacuum-solid interface contribute lowering threshold

Laser-induced damage threshold (LIDT) testing was performed on commercially-available multilayer dielectric coatings to qualify for use in the High Repetition-Rate Advanced Petawatt Laser System (HAPLS) Extreme Light Infrastructure Beamlines. Various tests were with uncompressed pulses (150 ps) from a 780 nm-centered Ti:Sapphire regenerative ampliflier, and raster scan method used determine best-performing coatings. Performance varied 2&ndash;8 J/cm² across samples 6 different...

Laser conditioning was investigated as a function of the temporal shape and duration 351 nm nanosecond pulses for fused-silica substrates polished via magnetorheological finishing. The aim is to advance our understanding dynamics involved enable improved control interaction laser light with material optimize conditioning. Gaussian that are temporally truncated at intensity peak observed enhance conditioning, in comparison pulse shape.