Femtosecond laser polymerization of hybrid/integrated micro-optical elements and their characterization

Abstract

The femtosecond laser-induced multi-photon polymerization of a zirconium–silicon based sol–gel photopolymer was employed for the fabrication of a series of micro-optical elements with single and combined optical functions: convex and Fresnel lenses, gratings, solid immersion lenses on a glass slide and on the tip of an optical fiber. The microlenses were produced as polymer caps of varying radii from 10 to 90 µm. The matching of refractive indices between the polymer and substrate was exploited for the creation of composite glass-resist structures which functioned as single lenses. Using this principle, solid immersion lenses were fabricated and their performance demonstrated. The magnification of the composite solid immersion lenses corresponded to the calculated values. The surface roughness of the lenses was below ∼ 30 nm, acceptable for optical applications in the visible range. In addition, the integration of micro-optical elements onto the tip of an optical fiber was demonstrated. To increase the efficiency of the 3D laser polymerization, the lenses were formed by scanning only the outer shell and polymerizing the interior by exposure to UV light.

Materials and technologies for fabrication of three-dimensional microstructures with sub-100 nm feature sizes by two-photon polymerization

“…Usually, oil immersion microscope objectives with high numerical apertures (NAs) up to 1.45 are applied in setups for 2PP. 12,15 The laser pulses are focused through index-matching oil and a coverslip into the polymer located on the bottom of the coverslip. These conventional microscope objectives suffer from two main drawbacks when applied for 2PP.…”

“…[1][2][3][4] Developments of new materials and illumination concepts like the STED lithography [5][6][7] have pushed the lateral dimensions of realizable structures below 100 nm. With the variability of the technology, several applications have emerged, e.g., in the field of micro-optics, where the fabrication of photonic crystals 8,9 or micro-optical elements [10][11][12][13] has been demonstrated. Furthermore, biomedical devices like scaffolds for cell growth [14][15][16][17] or small prostheses 18 could be realized.…”

Optically Clear and Resilient Free-Form <em>&micro;</em>-Optics 3D-Printed via Ultrafast Laser Lithography

“…Laser beam was focused to a ∼250 µm radius spot onto 50 µm diameter microlenses, resulting in I = 86.6 W/cm 2 . The microlenses were produced following procedure described earlier [24]. Intense laser radiation might induce changes both in the volume and on the surface of the microoptical element.…”

Direct laser writing by two-photon polymerization as a tool for developing microenvironments for evaluation of bacterial growth

“…An interesting approach is based on doping the host resin used in the 2PP with compounds of interest (organic dyes and bioactive agents). Such approach enables the fabrication of devices with specific characteristics for different areas of optics [8][9][10] and biology [11][12][13][14][15][16]. Furthermore, the manufacture of components using 2PP can be carried out in stages, allowing the fabrication of microdevices with multi-doping components [17].…”