Increasing Laser Fluence Research Articles

Laser sintering of screen-printed TiO2 nanoparticles for improvement of mechanical and electrical properties

Conducted research presents a rapid and cost-effective approach to technological processing of screen-printed films with anatase TiO2 nanoparticles, by utilizing the high fluence laser radiation. The influence of laser sintering on the screen-printed films was characterized with optical and scanning electron microscopy, energy-dispersive X-ray (EDX) spectroscopy, Raman spectroscopy, nanoindenter measurements and current vs voltage measurements. Investigation of surface morphology of screen-printed films revealed that higher laser fluences caused significant decrease in film thickness, trough evaporation of organic additives used in the paste matrix. EDX mapping of carbon content in untreated and laser sintered surface confirmed removal of organic additives. Laser sintering stimulated breaking of large agglomerates into much finer nano-sized particles and promoted formation of necking between individual grains. Crystal structure and vibrational properties of anatase TiO2 nanoparticles was monitored with Raman spectroscopy before and after laser sintering. Obtained results point out that anatase polymorph was preserved during the sintering process, without appearance of other phases. From observation of the behavior of the most intense Eg Raman active mode it was deduced that laser sintering provoked a formation of structural defects i.e. oxygen vacancies in TiO2 nanoparticles, whose concentration increased in the samples treated with higher laser fluences. Mechanical properties of untreated and laser sintered samples were investigated with nanoindenter measurements using several load forces, in order to carefully probe the Young modulus and mechanical hardness. From the analysis of collected data, we established that overall improvement of the mechanical properties with laser sintering originates from formation of very dense ceramic layer with enhanced interconnectivity between individual TiO2 nanoparticles. Measurements of current vs voltage characteristics clearly demonstrated that increase in laser fluence leads to drastic increase in current values and improvement of electric conductivity.

Effect of Laser Fluence on the Structural and Optical Properties of Tantalum Oxide Films Ablated by Pulsed Laser

The influence of laser fluence on the properties of thin films of tantalum oxide is studied in this paper, varying the laser fluence from 5.7 to 8.3 J/cm2. Thin films of tantalum oxide were deposited on glass substrates using pulsed-laser ablation technique. X-ray diffraction studies confirm the amorphous/nanocrystalline nature of all the films irrespective of the laser fluence. The Tauc plot analysis suggests that tantalum oxide is an indirect band gap material, whose band gap decreases with increase in laser fluence. The refractive index of the films is found to decrease with increase in laser fluence but the extinction coefficient of the films increases with increase in laser fluence. Fourier transform infrared studies suggest the use of tantalum oxide thin films as oxygen sensors. Micro-Raman analysis reveals the sensitiveness of Ta-O-Ta and Ta-O vibration modes to laser fluence. Among all the films, the film deposited at a laser fluence of 7 J/cm2 is found to be superior in quality.

Investigations on surface morphology and bandgap engineering of single crystal boron-doped silicon irradiated by a nanosecond laser.

We irradiate the single crystal boron-doped silicon (Si) at various laser fluences with 100 laser shots in ambient air at room temperature using an Nd:YAG laser and investigate its surface morphology and optical properties. The optical microscopy gives evidence of the formation of a crater and reveals that the heat-affected zone and melted area are increased with increase in laser fluence from 1.1 to 15.4 J/cm2. The micrographs obtained by scanning electron microscopy (SEM) show that the micro- and nano-structures such as microcracks, bubbles, nucleation sites, clusters, redeposited layered material, nanoparticles, and alike water droplet structures are formed on a laser-exposed Si surface. The optical profilometry of the irradiated Si further confirms the ablation and redeposition of the material and shows that the depth of the crater is increased from 12.1 to 15.2μm with increase in fluence from 1.1 to 15.4 J/cm2. Raman spectroscopy of the samples shows that the irradiation generates anneal effects due to higher temperature, which increases the crystallinity of the Si. The ellipsometric analysis shows that the irradiation of Si with increasing laser fluence changes its optical constants (refractive index and extinction coefficient), which further influence its optical properties, e.g.,reflectivity, absorptivity, and energy bandgap. The absorptivity of laser irradiated Si tends to increase with increasing laser fluence, and the energy bandgap is decreased accordingly due to increase in structural disorders. Our study shows that the controlled laser irradiation can tune the energy bandgap of exposed Si, and it makes the Si materials useful for the fabrication of optoelectronic devices such as solar cells, photovoltaic cells, and LEDs.

Influence of skin-layer microstructure in ultrafast laser surface treatment

In this work, the morphology of AISI 316L stainless steel surfaces, textured with ultrafast laser machining, was studied by scanning probe microscopy. In particular, correlations between the morphology and the polycrystalline microstructure of the material were searched. Topographic maps of the treated surfaces revealed a transition from small-sized to larger size and rather irregular features, driven by increase in laser fluence and depending on process parameters. In addition, a metrological analysis of the material grains demonstrated a shape and size similarity with laser-induced features attained for certain process parameters, suggesting that surface texture turns influenced by the microstructure of the skin-layer.

Laser initiation of RDX crystal slice under ultraviolet and near-infrared irradiations

Interactions between energetic materials and laser beams of specific frequency are of both scientific and engineering importance for understanding and manipulating the laser-induced ignition of energetic crystals. In this work, we investigate the effects of laser irradiation of variable energy densities from ultraviolet (355 nm) to near-infrared (1064 nm) on the ignition properties of a well-treated cyclotrimethylenetrinitramine (RDX) crystal slice (9.3 mm × 9.1 mm × 2.9 mm). The laser-induced damage and initiation dynamics were characterized in detail by using optical microscopy as well as an ultrafast pump-probe imaging technique at nanoseconds. It discloses that both ignition probabilities (p) of 355 and 1064 nm change exponentially with increasing laser fluence (H, J/cm2): p(355)=1−e−1.72*(H−3.981), p(1064)=1−e−0.74*(H−7.898). RDX crystals can be more easily ignited under ultraviolet laser irradiation than by near-infrared one due to its different absorptions (α(355) = 1.6306 cm−1, and α(1064) = 0.5313 cm−1) and the effects of photochemical initiation mechanism. The damage induced by either 355 nm or 1064 nm laser exhibits three typical morphologies varied with laser exposure. In addition, damage generated by ultraviolet laser appears on the incident surface of the crystal slice, while it is mainly located on the exit surface when being ignited by near-infrared laser. Our work sheds light on the dedicated interaction mechanism between energetic crystals and laser beams of various frequency and energy density.

Correlation between luminescence and structural evolution of colloidal silicon nanocrystals synthesized under different laser fluences

We present a detailed investigation of the structural evolution and photoluminescence (PL) properties of colloidal silicon (Si) nanocrystals (NCs) synthesized through femtosecond laser ablation at different laser fluences. It is shown that the mean size of colloidal Si NCs increases from ∼0.97–2.37 nm when increasing laser fluence from 1.0–2.5 mJ cm−2. On the basis of structural characterization, temperature-dependent PL, time-resolved PL, and PL excitation spectra, we identify that the size-dependent spectral shift of violet emission is attributed to the quantum confinement effect. The localized excitons’ radiative recombination via the oxygen-related surface states on the surface of the colloidal Si NCs is employed to explain the origin of the blue emission.

Integrated experimental and computational approach to laser machining of structural bone

This study describes the fundamentals of laser–bone interaction during bone machining through an integrated experimental-computational approach. Two groups of laser machining parameters identified the effects of process thermodynamics and kinetics on machining attributes at micro to macro. A continuous wave Yb-fiber Nd:YAG laser (wavelength 1070 nm) with fluences in the range of 3.18 J/mm2–8.48 J/mm2 in combination of laser power (300 W–700 W) and machining speed (110 mm/s–250 mm/s) were considered for machining trials. The machining attributes were evaluated through scanning electron microscopy observations and compared with finite element based multiphysics-multicomponent computational model predicted values. For both groups of laser machining parameters, experimentally evaluated and computationally predicted depths and widths increased with increased laser energy input and computationally predicted widths remained higher than experimentally measured widths whereas computationally predicted depths were slightly higher than experimentally measured depths and reversed this trend for the laser fluence >6 J/mm2. While in both groups, the machining rate increased with increased laser fluence, experimentally derived machining rate remained lower than the computationally predicted values for the laser fluences lower than ∼4.75 J/mm2 for one group and ∼5.8 J/mm2 for other group and reversed in this trend thereafter. The integrated experimental-computational approach identified the physical processes affecting machining attributes.

Photoporation Using Carbon Nanotubes for Intracellular Delivery of Molecules and Its Relationship to Photoacoustic Pressure.

Exposure of carbon-black (CB) nanoparticles to near-infrared nanosecond-pulsed laser energy can cause efficient intracellular delivery of molecules by photoporation. Here, cellular bioeffects of multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) are compared to those of CB nanoparticles. In DU145 prostate-cancer cells, photoporation using CB nanoparticles transitions from (i) cells with molecular uptake to (ii) nonviable cells to (iii) fragmented cells with increasing laser fluence, as seen previously. In contrast, photoporation with MWCNTs causes uptake and, at higher fluence, fragmentation, but does not generate nonviable cells, and SWCNTs show little evidence of bioeffects, except at extreme laser conditions, which generate nonviable cells and fragmentation, but no significant uptake. These different behaviors cannot be explained by photoacoustic pressure output from the particles. All particle types emit a single, ≈100 ns, mostly positive-pressure pulse that increases in amplitude with laser fluence. Different particle types emit different peak pressures, which are highest for SWCNTs, followed by CB nanoparticles and then MWCNTs, which does not correlate with cellular bioeffects between different particle types. This study concludes that cellular bioeffects depend strongly on the type of carbon nanoparticle used during photoporation and that photoacoustic pressure is unlikely to play a direct mechanistic role in the observed bioeffects.

Comprehensive studies of ultrashort laser pulse ablation of tin target at terawatt power

The fundamental properties of ultrashort laser interactions with metals using up to terawatt power were comprehensively studied, i.e., specifically mass ablation, nanoparticle formation, and ion dynamics using multitude of diagnostic techniques. Results of this study can be useful in many fields of research including spectroscopy, micromachining, thin film fabrication, particle acceleration, physics of warm dense matter, and equation-of-state determination. A Ti:Sapphire femtosecond laser system (110mJ maximum energy, 40fs, 800nm, P-polarized, single pulse mode) was used, which delivered up to 3 terawatt laser power to ablate 1mm tin film in vacuum. The experimental analysis includes the effect of the incident laser fluence on the ablated mass, size of the ablated area, and depth of ablation using white light profilometer. Atomic force microscope was used to measure the emitted particles size distribution at different laser fluence. Faraday cup (FC) detector was used to analyze the emitted ions flux by measuring the velocity, and the total charge of the emitted ions. The study shows that the size of emitted particles follows log-normal distribution with peak shifts depending on incident laser fluence. The size of the ablated particles ranges from 20 to 80nm. The nanoparticles deposited on the wafer tend to aggregate and to be denser as the incident laser fluence increases as shown by AFM images. Laser ablation depth was found to increase logarithmically with laser fluence then leveling off at laser fluence >400J/cm2. The total ablated mass tends to increase logarithmically with laser fluence up to 60J/cm2 while, increases gradually at higher fluence due to the increase in the ablated area. The measured ion emitted flux shows a linear dependence on laser fluence with two distinct regimes. Strong dependence on laser fluence was observed at fluences <350J/cm2. Also, a slight enhancement in ion velocity was observed with increasing laser fluence up to 350J/cm2.

Preparation and characteristics study of diamond like carbon/silicon heterojunction photodetector by pulsed laser deposition

In this paper, amorphous undoped diamond-like carbon films were deposited on glass and silicon substrates by pulsed laser ablation of graphite target; using nanoseconds frequency doubled Nd: YAG laser pulses. The effect of laser fluence (9.5–14.3 J/cm2) on optical, structural, morphological, and electrical properties of diamond like carbon films was studied by X-ray diffraction, Raman spectroscopy, Scanning electron microscopy, energy dispersive X-ray, Fourier transform infrared spectroscopy, photoluminescence, and UV–Vis transmittance. UV–Vis results revealed a decreased indirect optical band gap from 2.2 to 1.92 eV with increasing laser fluence from 9.5 to 14.3 J/cm2 leads. The ID/IG ratio and sp2 bonded percentage of DLC films increased with laser fluence increase. Films prepared at a higher laser fluence yield lower electrical resistivity. The dark and illuminated current–voltage characteristics at room temperature of diamond like carbon/Silicon heterojunction under the effect of laser flunce were examined and analyzed. Our results demonstrated an optimum photodetectors’ responsivity of 450 m AW−1 at 10 V bias.

Effect of laser processing on physical properties of (Ba0.85Ca0.15Ti0.9Zr0.1O3) lead-free thick films fabricated by the electrophoretic deposition

In this work, we have fabricated lead-free piezoelectric Ba0.85Ca0.15Ti0.9Zr0.1O3 thick films by the electrophoretic deposition (EPD) followed by a continuous-wave CO2 laser annealing and demonstrated the effect of laser energy on the quality of the final product. Thick films annealed under optimized conditions, 50 W/15 min, show a controlled microstructure/density compared to those derived from higher laser power/annealing time/conventional sintering. The increase in laser power above this limit affects the grain growth kinetics and results in the compositional heterogeneities. From the results of Raman spectra, it was found that the film annealed under optimized conditions has a high degree of crystallinity and tetragonality, while the increase in laser fluence results in the growth of A1g mode. The controlled composition and microstructure, thus has resulted in the improved ferroelectricity with a remanent polarization 12 μC/cm2, on par with the bulk or larger than the films grown by the chemical solution deposition techniques. From the piezoresponse studies, we found that the film annealed at 75 W/5 min has weak ferroelectric nature with no switchable ferroelectric domains compared to those under optimized conditions. Subtle differences in phase transition temperatures and drop in ferroelectric polarization, for films annealed conventionally or at higher laser fluence, are related to porosity or site defects as well as compositional heterogeneities. Our study demonstrates that the combination of EPD and laser annealing is an effective way to achieve high quality piezoelectric thick films with a controlled composition, useful for energy harvesting applications.

Tunable photoacoustic properties of gold nanoshells with near-infrared optical responses

Photoacoustic (PA) properties of liquid-immersed gold nanoshells (GNSs) with near-infrared optical responses are investigated using the finite element method. We focus on the dependence of the PA signal of the GNS on the geometry, surrounding medium, laser fluence, and laser pulse width. It is found that the PA signal of the GNS is strongly sensitive to the optical absorption of the GNS and can be greatly modulated by changing the geometry. At the wavelength of 800 nm, the maximal PA signal could be obtained for the GNS with the optimized size of the inner radius (r1 = 48.5 nm) and outer radius (r2 = 57 nm). The increased laser fluence enhances the optical absorption and PA signal. The decreased laser pulse width induces the decreased PA pulse width, the increased bandwidth of the PA signal, and the increased PA conversion efficiency, resulting in the enhanced PA signal. In addition, we find that the larger Gruneisen parameter of the embedding medium leads to a stronger PA signal.

Estimation of ion accelerating potential inside the nanosecond pulsed laser produced tungsten plasma

Plasma plume generated by neodymium-doped yttrium aluminium granite laser (wavelength = 1064 nm, pulse duration = 6 ns) focused onto a planar tungsten target is investigated with the help of ion collector (IC) and electrostatic ion energy analyzer (IEA) operating in time-of-flight configuration. Laser fluence was in the range of 7–20 J/cm2. The IEA spectra showed that the charge state of tungsten ions emitted from the plume increases with the laser fluence and W6+ was the highest ion charge state detected in the investigated range of the laser fluence. Coulomb–Boltzmann-shifted time function was used to determine ion intensities and peak energies of the various ion charge states from the measured IC spectra. Depending on the charge state, the energies of various ion charge states were in the range of 0.6–2.7 keV. The experimental data were exploited to estimate the equivalent accelerating potential developed inside the plume. The equivalent accelerating potential was found to increase linearly with the increase of laser fluence. The comparison with literature data revealed that the equivalent accelerating potential also increases with the atomic number of the target material. These results are in good agreement with the predictions of the electrostatic model for ion acceleration in laser plasma.

Mid-infrared femtosecond laser-induced damages in As2S3 and As2Se3 chalcogenide glasses

In this paper, we report the first measurements of mid-infrared (MIR) femtosecond laser-induced damage in two typical chalcogenide glasses, As2S3 and As2Se3. Damage mechanism is studied via optical microscopy, scanning electron microscopy and elemental analysis. By irradiating at 3, 4 and 5 μm with 150 fs ultrashort pulses, the evolution of crater features is presented with increasing laser fluence. The dependence of laser damage on the bandgap and wavelength is investigated and finally the laser-induced damage thresholds (LIDTs) of As2S3 and As2Se3 at 3 and 4 μm are calculated from the experimental data. The results may be a useful for chalcogenide glasses (ChGs) applied in large laser instruments to prevent optical damage.

A coupling model to simulate the dynamic process of blister-actuated nanosecond laser-induced forward transfer

The modeling of laser-induced forward transfer process (LIFT) is helpful to understand and optimize its complex transfer process. In this work, a coupling model is developed to investigate the dynamic response of a thin polymer layer used as the release layer in the blister-actuated LIFT. In this model, the vapor pressure generated by nanosecond laser irradiation is computed through coupling with the transient vapor volume obtained from different step durations to simulate the dynamic blister formation. And the model is validated by experiments on polyimide film irradiated with different laser fluences, which is found to be capable of providing a consistent prediction of blister profiles under several laser conditions. The calibrated energy conversion ratios imply that laser pulse energy is mainly allocated for the heating and vaporizing of polymers, but increasing laser fluence can make this expense gradually saturated to allow more pulse energy to increase the vapor pressure. Transient pressure development from the coupling model is observed to increase rapidly within the pulse duration, but then to decrease because of vapor expansion. Forward velocity in axial direction is also observed to increase with laser fluence. The maximum velocity is possible to exceed the sound velocity under a high laser fluence. And the thin polymer layer is more preferred to obtain a high transfer velocity.

Polarization and fluence effects in femtosecond laser induced micro/nano structures on stainless steel with antireflection property

In this paper, micro/nano structures on stainless steel were prepared in single spot irradiation mode and scan mode by using femtosecond laser technique. The influence of polarization and fluence on the formation of micro/nano structures were explored. Surface morphology, microstructure, roughness and composition of prepared samples were characterized. The antireflection property and wettability of laser treated samples were also tested and compared with that of original stainless steel.Results showed that the laser-induced spot consists of two distinct regions due to the Gaussian beam profile: a core region of moth-eye-like structure and a peripheral region of nanoparticles-covered laser-induced periodic surface structure (NC-LIPSS). The proportion of the core region and dimension of micro/nano structure increase with increasing laser fluence. Polarization can be used to tune the direction of NC-LIPSS. Atomic ratios of Cr and Mn increase and atomic ratio of Ni decreases after laser irradiation. Oxygen is not detected on laser irradiated samples, indicating that oxidation reactions are not significant during the interaction process between femtosecond laser and 304 stainless steel. These are good for the application of stainless steel as its physical properties would not change or even enhanced. The overlaps between two laser scan lines significantly influence the surface roughness and should be controlled carefully during the preparation process. The laser irradiated surface has a better antireflection property in comparison with that of original stainless steel, which may due to the scattering and absorption of micro/nano structures. Contact angle of micro/nano structured stainless steel decreases with the increase of laser fluence. The hydrophilic property can be explained by Wenzel’s model. The interference between the surface plasmon wave and the incident light wave leads to the formation of NC-LIPSS.

Ultraviolet-Diode Pump Solid State Laser Removal of Titanium Aluminium Nitride Coating from Tungsten Carbide Substrate

This paper presents an investigation on the titanium aluminium nitride (TiAlN) coating removal from tungsten carbide (WC-Co) substrate using a diode pump solid state (DPSS) ultraviolet (UV) laser with maximum average power of 90 W, wavelength of 355 nm and pulse width of 50 ns. The TiAlN coating of 1.5 μm thickness is removed from the WC-Co substrate with laser fluence of 2.71 J/cm2 at 285.6 number of pulses (NOP) and with NOP of 117.6 at 3.38 J/cm2 fluence. Titanium oxide formation was observed on the ablated surface due to the re-deposition of ablated titanium residue and also attributed to the high temperature observed during the laser ablation process. Crack width of around 0.2 μm was observed over both TiAlN coating and WC-Co substrate. The crack depth ranging from 1 to 10 μm was observed and is related to the thickness of the melted carbide. The crack formation is a result of the thermal induced stresses caused by the laser beam interaction with the material as well as the higher thermal conductivity of cobalt compared to WC. Two cleaning regions are observed and is a consequence of the Gaussian distribution of the laser beam energy. The surface roughness of the ablated WC-Co increased with increasing laser fluence and NOP.

The role of spatial confinement for improvement of laser-induced Mg plasma parameters and growth of surface features

The role of spatial confinement for improvement of laser-induced Mg plasma parameters and growth of surface features is investigated by introducing a metallic blocker. Nd: YAG laser at various fluences ranging from 7 to 28 J cm−2 was employed as an irradiation source. All measurements were performed in the presence of Ar under different pressures. Confinement effects offered by metallic blocker are investigated by placing the blocker at different distances of 6, 8 and 10 mm from the target surface. It is revealed from laser-induced breakdown spectroscopy analysis that both plasma parameters, i.e., excitation temperature and electron number density initially increase with increasing laser fluence due to enhancement in energy deposition. With further increase in laser fluence, a decreasing trend followed by saturation is observed which is attributable to shielding effect and self-regulating regime. It is also observed that spatial confinement offered by metallic blocker is responsible for the significant enhancement of both electron temperature and electron number density of Mg plasma. This is true for all laser fluences and pressures of Ar. Maximum values of electron temperature and electron number density without blocker are 8335 K and 2.4 × 1016 cm−3, respectively, whereas these values are enhanced to 12,200 K and 4 × 1016 cm−3 in the presence of the blocker. The physical mechanisms responsible for the enhancement of Mg plasma parameters are plasma compression, confinement and pronounced collisional excitations due to reflection of shock waves. Scanning electron microscope analysis was performed to explore the surface morphology of laser-ablated Mg. It reveals the formation of cones, cavities and ripples. These features become more distinct and well defined in the presence of the blocker due to plasma confinement. The optimum combination of blocker distance, fluence and Ar pressure can identify the suitable conditions for defining the role of plasma parameters for surface structuring.

Spatial confinement effects on spectroscopic and morphological studies of nanosecond laser-ablated Zirconium

Spatial confinement effects on plasma parameters and surface morphology of laser ablated Zr (Zirconium) are studied by introducing a metallic blocker. Nd:YAG laser at various fluencies ranging from 8Jcm−2 to 32Jcm−2 was employed as an irradiation source. All measurements were performed in the presence of Ar under different pressures. Confinement effects offered by metallic blocker are investigated by placing the blocker at different distances of 6mm, 8mm and 10mm from the target surface. It is revealed from LIBS analysis that both plasma parameters i.e. excitation temperature and electron number density increase with increasing laser fluence due to enhancement in energy deposition. It is also observed that spatial confinement offered by metallic blocker is responsible for the enhancement of both electron temperature and electron number density of Zr plasma. This is true for all laser fluences and pressures of Ar. Maximum values of electron temperature and electron number density without blocker are 12,600K and 14×1017cm−3 respectively whereas, these values are enhanced to 15,000K and 21×1017cm−3 in the presence of blocker. The physical mechanisms responsible for the enhancement of Zr plasma parameters are plasma compression, confinement and pronounced collisional excitations due to reflection of shock waves. Scanning Electron Microscope (SEM) analysis was performed to explore the surface morphology of laser ablated Zr. It reveals the formation of cones, cavities and ripples. These features become more distinct and well defined in the presence of blocker due to plasma confinement. The optimum combination of blocker distance, fluence and Ar pressure can identify the suitable conditions for defining the role of plasma parameters for surface structuring.

Rutile TiO2 Flocculent Ripples with High Antireflectivity and Superhydrophobicity on the Surface of Titanium under 10 ns Laser Irradiation without Focusing.

We report on the formation of rutile TiO2 flocculent laser-induced periodic surface structures (LIPSSs) with high antireflectivity and superhydrophobicity on the surface of titanium under 10 ns 1064 nm laser irradiation without focusing. The center part of the Gaussian laser beam is used to deposit flocculent structure and the edge part used to produce LIPSSs. The melt and modification thresholds of titanium were determined first, and then, the melt and modification spot-overlap numbers, several responsible for the formation of flocculent structure and LIPSSs, were introduced. It is found that both the melt and modification spot-overlap numbers increase with an increase in laser fluence and spot-overlap number, contributing to the production of flocculent LIPSSs. LIPSSs are obtained with the modification spot-overlap number above 300, and the amount of flocculent structures increases with an increase in the peak laser fluence and spot-overlap number. Then, considering that the fine adjustment of the melt and modification spot-overlop numbers in one-time line scanning is quite difficult, the composite structure, of which both LIPSSs and flocculent structures are distinct, was optimized using laser line scanning twice. On this basis, a characterization test shows the sample full of the flocculent LIPSSs represents best antireflectivity with the value around 10% in the waveband between 260 and 2600 nm (advance 5 times in infrared wavelengths compared to the initial titanium surface), and shows the no-stick hydrophobicity with the contact angle of 160° and roll-off angle of 25° because of the pure rutile phase of TiO2.