title: Confocal Raman imaging of optical waveguides in LiNbO3 fabricated by ultrafast high-repetition rate laser-writing.
abstract: We report on the confocal Raman characterization of the micro-structural lattice changes induced during the high-repetition rate ultrafast laser writing of buried optical waveguides in lithium niobate (LiNbO(3)) crystals. While the laser beam focal volume is characterized by a significant lattice expansion together with a high defect concentration, the adjacent waveguide zone is largely free of defects, undergoing only slight rearrangement of the oxygen octahedron in the LiNbO(3) lattice. The close proximity of these two zones has been found responsible for the propagation losses of the guided light. Subjacent laser-induced periodic micro-structures have been also observed inside the laser focal volume, and identified with a strong periodic distribution of lattice defects.
authors.affiliation: GIEL, Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Airán
authors.initials: A
authors.lastname: Ródenas
authors.forename: Amir H
authors.initials: AH
authors.lastname: Nejadmalayeri
authors.forename: Daniel
authors.initials: D
authors.lastname: Jaque
authors.forename: Peter
authors.initials: P
authors.lastname: Herman
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D018613:Microscopy, Confocal / Q000295:instrumentation*; D009556:Niobium / Q000737:chemistry* / Q000528:radiation effects; D055095:Optics and Photonics / Q000295:instrumentation*; D010087:Oxides / Q000737:chemistry* / Q000528:radiation effects; D012031:Refractometry / Q000295:instrumentation*; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*; D013499:Surface Properties
chemical_list: D010087:Oxides; D009556:Niobium; C091692:lithium niobate