We have studied plasmonic optical tweezers (POT) for nanomaterials such as DNA and polymers. These nanomaterials would be efficiently trapped by a plasmon-enhanced optical force. However, plasmon excitation also leads to a photothermal effect. Such heat generation has frequently hindered POT. Recently, we have developed a novel optical trapping technique; Nano-Structured Semi-Conductor-Assisted (NASSCA) optical tweezers. In NASSCA optical tweezers, we used a metal-free black silicon with a nanoneedles structure on the surface. NASSCA optical tweezers presents a useful and powerful manipulation technique without heat generation.
Nano-texturing of surface by self-organised ablation ripples as well as modifications of internal volume of materials, transparent at the wavelength of laser irradiation, is gaining interest due to simplicity of direct laser writing/printing. With ultra-short laser pulses (τ<sub><i>p</i></sub> < 1 ps) a wider range of structuring morphologies is accessible, namely, sub-wavelength ripples. The surface wave formed on the plasma-dielectric (air or substrate) explains difference of the formed pattern. These corresponding front- and back-side (in respect to the incoming laser beam) modes of laser structuring accounts for the ripple formation inside transparent materials, where a skin-layer plasma is formed. Emerging applications of nano-textured surfaces for bio-medical field are discussed.