Lithographically aligned 3D optical microsystems with high gradient index contrast

Using two-photon lithography to pattern materials within a 3D nanoporous scaffold has been demonstrated as a general approach to 3D nanofabrication. Here we demonstrate centimeter-scale, free-standing, highly transparent nanoporous silica scaffolds within which two-photon polymerization can create refractive index gradients with contrast > 0.5. This enables 90-degree total internal reflection prisms for efficient 3D routing of light. The combination of arbitrary 3D geometries, nanoscale resolution, and gradient control of refractive index with ∆n > 0.5 can enable the creation of fully integrated 3D optical microsystems, transforming optics and photonics in a manner similar to how planar lithography transformed electronics.