title: Freeform three-dimensional embedded polymer waveguides enabled by external-diffusion assisted two-photon lithography.
abstract: This paper introduces a unique method to fabricate free-form symmetrical three-dimensional single-mode waveguides embedded in a newly developed photopolymer. The fabrication process requires only one layer of a single material by combining two-photon lithography and external monomer diffusion resulting in a high refractive index contrast of 0.013. The cured material exhibits high chemical and thermal stability. Transmission loss of 0.37  dB/cm at 850 nm is achieved. Due to the fact that waveguide arrays are produced with high density, this technique could pave the way for three-dimensional optical interconnects at the board level with high complexity and bandwidth density.
authors.forename: Ho Hoai
authors.initials: HH
authors.lastname: Duc Nguyen
authors.forename: Uwe
authors.initials: U
authors.lastname: Hollenbach
authors.forename: Ute
authors.initials: U
authors.lastname: Ostrzinski
authors.forename: Karl
authors.initials: K
authors.lastname: Pfeiffer
authors.forename: Stefan
authors.initials: S
authors.lastname: Hengsbach
authors.forename: Juergen
authors.initials: J
authors.lastname: Mohr