Direct laser writing of high refractive index contrast volumetric photonics

Here, we present Subsurface Controllable Refractive Index via Beam Exposure (SCRIBE), a direct-write lithographic approach that enables fabrication of low-loss volumetric microscale gradient refractive index lenses, waveguides, and metamaterials with a resolution of better than one micron. The basis of SCRIBE is multiphoton polymerization inside monomer-filled nanoporous silicon and silica scaffolds. Adjusting the laser exposure during printing enables 3D submicron control of the polymer infilling and thus the refractive index over a range of greater than 0.3 and chromatic dispersion tuning. A Luneburg lens operating at visible wavelengths, achromatic doublets, multicomponent optics, photonic nanojets and subsurface 3D waveguides were all formed. Various optical elements were combined to create the building blocks for volumetric photonic integrated circuits.