title: Low-loss waveguides written with a femtosecond laser for flexible interconnection in a planar light-wave circuit.
abstract: We describe a low-loss single-mode waveguide in planar light-wave circuit (PLC) glass doped with boron and phosphorus, which is more difficult to write than pure-silica glass. The written waveguide has a rectangular core, a symmetric near-field pattern, and a propagation loss of 0.35 dB/cm. The loss that originates from the mode-field mismatch between the mode-field diameters of the written and the PLC waveguides is less than 0.1 dB/point. In addition, we successfully connected PLC waveguides with a 500-microm-long waveguide written with a laser. The laser-written waveguide can flexibly connect PLC waveguides with a low coupling loss.
authors.affiliation: NTT Photonics Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi-Shi, Kanagawa Prefecture, 243-0198, Japan. nasu@aecl.ntt.co.jp
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nasu
authors.forename: Masaki
authors.initials: M
authors.lastname: Kohtoku
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Hibino