Fabrication of Optical Microstructures with Gradient Refractive Index by Two-Photon Laser Lithography

The method of two-photon lithography is used to fabricate microstructures with gradient of refractive index. The rectangular structures with sizes 25 × 25 × 3 μm were fabricated with varying laser intensity by linear or Gaussian distribution in one dimension. The resulting refractive index has been tuned in the range of 0.03. The suggested method can be applied to produce arbitrarily shaped 3D GRIN micro-optical elements.