title: Direct laser-writing of ferroelectric single-crystal waveguide architectures in glass for 3D integrated optics.
abstract: Direct three-dimensional laser writing of amorphous waveguides inside glass has been studied intensely as an attractive route for fabricating photonic integrated circuits. However, achieving essential nonlinear-optic functionality in such devices will also require the ability to create high-quality single-crystal waveguides. Femtosecond laser irradiation is capable of crystallizing glass in 3D, but producing optical-quality single-crystal structures suitable for waveguiding poses unique challenges that are unprecedented in the field of crystal growth. In this work, we use a high angular-resolution electron diffraction method to obtain the first conclusive confirmation that uniform single crystals can be grown inside glass by femtosecond laser writing under optimized conditions. We confirm waveguiding capability and present the first quantitative measurement of power transmission through a laser-written crystal-in-glass waveguide, yielding loss of 2.64 dB/cm at 1530 nm. We demonstrate uniformity of the crystal cross-section down the length of the waveguide and quantify its birefringence. Finally, as a proof-of-concept for patterning more complex device geometries, we demonstrate the use of dynamic phase modulation to grow symmetric crystal junctions with single-pass writing.
authors.affiliation: Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Stone
authors.affiliation: Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015, USA.
authors.forename: Himanshu
authors.initials: H
authors.lastname: Jain
authors.affiliation: Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, PA 18015, USA.
authors.forename: Volkmar
authors.initials: V
authors.lastname: Dierolf
authors.affiliation: Office of Society-Academia Collaboration for Innovation, Kyoto University, Goryo-ohara 1-30, Kyoto 615-8245, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Sakakura
authors.affiliation: Department of Material Chemistry, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Shimotsuma
authors.affiliation: Department of Material Chemistry, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Miura
authors.affiliation: Department of Material Chemistry, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Hirao
authors.affiliation: Department of Engineering Physics, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada.
authors.forename: Jerome
authors.initials: J
authors.lastname: Lapointe
authors.affiliation: 1] Department of Engineering Physics, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada [2] Department of Electrical Engineering, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada.
authors.forename: Raman
authors.initials: R
authors.lastname: Kashyap