Direct (3+1)D laser writing of graded-index optical elements

We propose single-step additive fabrication of graded-index optical elements by introducing the light exposure as additional dimension to three-dimensional (3D) laser writing, hence (3+1)D writing. use a commercial printer and photoresist realize proposed single step method that can be swiftly adopted for research engineering. After presenting characterization profiles via basic structures, we demonstrate two different devices: volume holograms are superimposed using angular peristrophic multiplexing, waveguides with well-defined refractive index profiles. In latter, precisely control propagating modes tuning (3+1)D-printed waveguide parameters report step-index core-cladding transitions.