title: Laser recrystallization and inscription of compositional microstructures in crystalline SiGe-core fibres.
abstract: Glass fibres with silicon cores have emerged as a versatile platform for all-optical processing, sensing and microscale optoelectronic devices. Using SiGe in the core extends the accessible wavelength range and potential optical functionality because the bandgap and optical properties can be tuned by changing the composition. However, silicon and germanium segregate unevenly during non-equilibrium solidification, presenting new fabrication challenges, and requiring detailed studies of the alloy crystallization dynamics in the fibre geometry. We report the fabrication of SiGe-core optical fibres, and the use of CO2laser irradiation to heat the glass cladding and recrystallize the core, improving optical transmission. We observe the ramifications of the classic models of solidification at the microscale, and demonstrate suppression of constitutional undercooling at high solidification velocities. Tailoring the recrystallization conditions allows formation of long single crystals with uniform composition, as well as fabrication of compositional microstructures, such as gratings, within the fibre core.
authors: Department of Physics, Høgskoleringen 5, NTNU, Norwegian University of Science and Technology, Trondheim 7491, Norway.
authors: David A
authors: DA
authors: Coucheron
authors: Department of Applied Physics, KTH Royal Institute of Technology, Roslagstullsbackan 21, Stockholm 100-44, Sweden.
authors: Michael
authors: M
authors: Fokine
authors: Department of Physics, Høgskoleringen 5, NTNU, Norwegian University of Science and Technology, Trondheim 7491, Norway.
authors: Nilesh
authors: http://orcid.org/0000-0002-5130-689X
authors: N
authors: Patil
authors: Department of Physics, Høgskoleringen 5, NTNU, Norwegian University of Science and Technology, Trondheim 7491, Norway.|Department of Micro- and Nano System Technology, University College of Southeast Norway, Campus Vestfold, Raveien 215 N-3184 Borre, Norway.
authors: Dag Werner
authors: DW
authors: Breiby
authors: Department of Physics, Høgskoleringen 5, NTNU, Norwegian University of Science and Technology, Trondheim 7491, Norway.
authors: Ole Tore
authors: OT
authors: Buset
authors: Optoelectronics Research Centre, University of Southampton, Highfield, Southampton, Hampshire SO17 1BJ, UK.|Physics Department, Emerging Technology and Materials Group, Newcastle University, Merz Court, Newcastle NE1 7RU, UK.
authors: Noel
authors: N
authors: Healy
authors: Optoelectronics Research Centre, University of Southampton, Highfield, Southampton, Hampshire SO17 1BJ, UK.
authors: Anna C
authors: AC
authors: Peacock
authors: Department of Materials Science and Engineering and the Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University, Clemson, SC 29634, USA.
authors: Thomas
authors: T
authors: Hawkins
authors: Department of Materials Science and Engineering and the Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University, Clemson, SC 29634, USA.
authors: Max
authors: M
authors: Jones
authors: Department of Materials Science and Engineering and the Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University, Clemson, SC 29634, USA.
authors: John
authors: J
authors: Ballato
authors: Department of Physics, Høgskoleringen 5, NTNU, Norwegian University of Science and Technology, Trondheim 7491, Norway.|Department of Applied Physics, KTH Royal Institute of Technology, Roslagstullsbackan 21, Stockholm 100-44, Sweden.
authors: Ursula J
authors: http://orcid.org/0000-0002-8548-8791
authors: UJ
authors: Gibson