title: 3D laser-written silica glass step-index high-contrast waveguides for the 3.5 μm mid-infrared range.
abstract: We report on the direct laser fabrication of step-index waveguides in fused silica substrates for operation in the 3.5 μm mid-infrared wavelength range. We demonstrate core-cladding index contrasts of 0.7% at 3.39 μm and propagation losses of 1.3 (6.5) dB/cm at 3.39 (3.68) μm, close to the intrinsic losses of the glass. We also report on the existence of three different laser modified SiO₂ glass volumes, their different micro-Raman spectra, and their different temperature-dependent populations of color centers, tentatively clarifying the SiO₂ lattice changes that are related to the large index changes.
authors.forename: Javier
authors.initials: J
authors.lastname: Martínez
authors.forename: Airán
authors.initials: A
authors.lastname: Ródenas
authors.forename: Toney
authors.initials: T
authors.lastname: Fernandez
authors.forename: Javier R
authors.initials: JR
authors.lastname: Vázquez de Aldana
authors.forename: Robert R
authors.initials: RR
authors.lastname: Thomson
authors.forename: Magdalena
authors.initials: M
authors.lastname: Aguiló
authors.forename: Ajoy K
authors.initials: AK
authors.lastname: Kar
authors.forename: Javier
authors.initials: J
authors.lastname: Solis
authors.forename: Francesc
authors.initials: F
authors.lastname: Díaz