Two-photon lithography of nanorods in SU-8 photoresist

Abstract

Studies on two-photon lithography in negative SU-8 photoresist demonstrate the possibility of obtaining mechanically stable, stress-free, extended nanorods having lateral sizes of about 30 nm (corresponding to λ/25 resolution). The high resolution achievable with the given combination of materials and fabrication techniques demonstrates its potential for the fabrication of large-scale nanostructures, such as photonic crystals with photonic stop gaps at visible wavelengths.

Dynamic Bragg Angle Shift in the Course of Volume Hologram Formation

“…[11] Here, we report about an epoxy-based CROP material with a convincing performance and a free surface that shows great promise for advanced integrated systems. [4,5] Mechanical stability gains particular importance in view of the high-resolution nanostructures achievable with material based on SU-8 photoresist [18] and with regard to further reduction of feature sizes. [8] Epoxides are used as cationically polymerizable monomer to obtain high performance in terms of inducible refractive index contrast, [4] energetic sensitivity [19] as well as mechanical stability.…”

Femtosecond visible light induced two-photon photopolymerization for 3D micro/nanostructuring in photoresists and photopolymers

“…This femtosecond laser processing technology has drawn a great interest over the last decade because of the following reasons: (i) it can fabricate any kind of 3D structures out of photopolymer based on computer generated 3D model; (ii) the fabrication procedure is rapid and flexible; (iii) the spatial resolution of the structures can be as small as 100 nm; (iv) the fabrication process allows formation of structures directly integrating them into more complex functional micro-devices. There has been a considerable amount of research done by many authors during the last decade revealing the physics of this fabrication technology [1][2][3][4][5][6][7][8].…”

“…This confines polymerization area to be spatially highly localized at the focal point of a laser beam [3,4]. By precisely moving sample or beam focus position one can point-by-point solidify the photopolymer.…”

“…Recently, a number of this type 3D fabrication experiments were successfully accomplished by applying Ti:sapphire femtosecond lasers generating 800 nm central wavelength light and using commercially available materials such as epoxy based SU-8 photoresins, hybrid organic-inorganic ORMOCER materials, and various blends of acrylates [4][5][6][7][8]. LTPP as a fabrication technology could be applicable in areas of micro-optics, photonics, micro-fluidics, micro-optoelectromechanical systems (MOEMS), tissue engineering, etc.…”

Self-polymerization of nano-fibres and nano-membranes induced by two-photon absorption

“…Nonlinear character of the two-photon absorption and chemical threshold of required radical concentration (C th ) for irreversible cross-linking results in high localization of the photomodified volume and the minimum size of a voxel being far below the size of beam waist limited by diffraction [2]. Thus, moving of the beam focal position in 3D enables Direct Laser Writing (DLW) of arbitrary polymer structures with sub-wavelength resolution [3]. This DLW technique often referred to as LTPP has emerged as a tool for the rapid, cheap, and flexible fabrication of 3D nanostructures in photonics, microoptics, nanofluidics, and nanomechanics.…”