title: Low-loss waveguides fabricated in BK7 glass by high repetition rate femtosecond fiber laser.
abstract: For the first time femtosecond-laser writing has inscribed low-loss optical waveguides in Schott BK7 glass, a commercially important type of borosilicate widely used in optical applications. The use of a variable repetition rate laser enabled the identification of a narrow processing window at 1 MHz repetition rate with optimal waveguides exhibiting propagation losses of 0.3 dB/cm and efficient mode matching to standard optical fibers at a 1550 nm wavelength. The waveguides were characterized by complementary phase contrast and optical transmission microscopy, identifying a micrometer-sized guiding region within a larger complex structure of both positive and negative refractive index variations.
authors.affiliation: Department of Electrical and Computer Engineering and Institute for Optical Sciences, University of Toronto, Toronto, Ontario, Canada. shane.eaton@utoronto.ca
authors.forename: Shane M
authors.initials: SM
authors.lastname: Eaton
authors.forename: Mi Li
authors.initials: ML
authors.lastname: Ng
authors.forename: Jörn
authors.initials: J
authors.lastname: Bonse
authors.forename: Alexandre
authors.initials: A
authors.lastname: Mermillod-Blondin
authors.forename: Haibin
authors.initials: H
authors.lastname: Zhang
authors.forename: Arkadi
authors.initials: A
authors.lastname: Rosenfeld
authors.forename: Peter R
authors.initials: PR
authors.lastname: Herman