Femtosecond Laser Texturing of Ti-6Al-4V: From Ablation Behavior to Controlled Bi-Sinusoidal Surface Morphology

This work presents a systematic methodology for generating bi-sinusoidal surface topographies with controlled and reproducible characteristics on Ti-6Al-4V using a progressive 1D–2D–3D framework. Such deterministic topographies are of interest for dental implants, where surface micro-texture can influence an early biological response and osseointegration. Single-pulse ablation thresholds were first determined to be 0.175 J/cm2 at a 1031 nm wavelength using 306 fs pulses, with no polarization dependence. Studies were then carried out to identify fundamental ablation parameters, optimize scanning conditions for planar texturing, and extend the process to controlled three-dimensional surface architectures. During the 1D stage, increasing the fluence from 0.26 to 6.52 J/cm2 enlarged the crater diameter from approximately 7 to 32 µm and increased the areal roughness Sa from 0.012 to 0.020 µm. With an increasing pulse number, the crater diameter continued to grow up to 25 pulses before stabilizing. Multi-pulse tests below the threshold showed that repeated exposures caused ablation, highlighting incubation and energy accumulation, with an incubation factor of S = 0.84. In the 2D stage, scanned irradiation was used to quantify how fluence and pulse overlap affect the ablated depth and areal roughness, with depth increasing linearly with the number of passes, and roughness strongly governed by overlap and fluence. Finally, 3D texturing combining x–y scanning with a z-axis focal adjustment enabled reproducible bi-sinusoidal topographies.