Photolithographic Fabrication of Addressable, sub-micron Resolution Three Dimensional Index Structures at Millimeter Scales
One and two dimensional spatial control of refractive index has produced successful commercial innovations such as lenses and optical fibers. Devices with spatial control of all three dimensions which have both high resolution and volumes of mm3 or larger have been impossible to fabricate due to either unworkable technologies or processing time requirements. Using a new lithographic technique, we are able to overcome these limitations and fabricate sub micron resolution, addressable three dimensional index structures throughout an entire mm3 volume of a diffusion driven photopolymer. By using liquid materials and a non-contact soft mold that planarizes each new layer; multiple tools are not required and processing sequential layers becomes faster. The non-contact soft mold also provides a short diffusion path for the material resulting in rapid fabrication of thick, high axial resolution devices. Using these innovations we demonstrate sub micron resolution index features in all three dimensions throughout a mm3 device. This technique could be used to fabricate devices such as a Luneburg lens operating in the visible, aberration corrected contact lenses, conformally mapped metamaterials, 3D photonic crystals and Optical Circuits.