Multiphoton Photolithography

Multiphoton lithographic methods afford unique advantages over one photon procedures in that they are inherently depth-resolved, allowing for 3D structures to easily be fabricated, as demonstrated by a number of other research groups. Our initial contributions to this field came in the demonstration of selective photobleaching in single micrometer-sized dyed-doped polystyrene spheres positioned within 3D colloidal crystal arrays.[30] Since that time, we have demonstrated that multiphoton processes excited using relatively weak pulses of near-IR light from a Ti:sapphire oscillator can induce ablative removal of polymeric materials from surfaces.[60,61,65,68] We quantitatively described the light-materials interactions in these studies and showed we could predict the order of the process and the expected spatial resolution of ablation. While numerous reports of ablative multiphoton photolithography have been reported in the past, all, to our knowledge, used much greater pulse powers and afforded far less control over materials removal. In our most recent paper, we demonstrated gray-scale patterning of surfaces and reported 1 nm precision in the depth-resolved removal of semiconducting polymeric materials from a surface.[68] Much of the later work was carried out in collaboration with Takashi Ito.

Reference numbers refer to articles in the Higgins Group publication list