Creation of Three-Dimensional Micro-Photonic Structures on the End-Face of Optical Fibers

Abstract

A process is reported that enables fabrication of truly three-dimensional micro-photonic structures directly onto the end face of an optical fiber by multi-photon direct laser writing in the cross-linkable epoxide SU-8. Solvent-free SU-8 resin is first obtained by heating in vacuo to remove volatiles. The resulting resin solids are then melt-reflowed around an optical fiber in a mold integrated into a sample mount. The resin is allowed to cool and solidify around the optical fiber, so the entire sample mount can be affixed to an optical system for direct laser writing. Using this approach a wide range of refractive and diffractive micro-optical structures can be integrated onto optical fibers that would be difficult, if not impossible, to create by other existing methods. Optical characterization of lens-tipped fibers shows that the approach can be used control the propagation of beams exiting from functionalized fibers, and the performance is reproducible across repeated fabrication of the same device. This work illustrates a new path to fiber-based integrated photonic devices.