Structural characterization of As-S-Se glasses for waveguide applications using near-infrared raman spectroscopy
Chalcogenide glasses (ChG) have shown very promising properties for integrated optical applications at the 1.3 and 1.55 µm optical communication wavelengths due to their transparency in the near-infrared region and high nonlinear Kerr effect. Recent experiments on the ChG system have demonstrated the vast flexibility and potential of these materials in applications as optical memories, switches, and diffractive elements, as well as couplers and self-written planar waveguides. However, to advance these novel applications, it is crucial to identify the structure-property relationship in the glass, in both bulk and film materials. Throughout this research work we used conventional near-infrared (NIR) Raman spectroscopy (e.g. backscattering and 90° geometry) to investigate structure-property relationships in chalcogenide materials. Initially, we conducted a homogeneity study of the bulk glass to analyze the elaboration and processing conditions of these glasses. Furthermore, we investigated the compositional variation of the bulk glass and established a relationship between the Raman spectra, and hence their molecular structure, with the optical properties of the material. When the analysis of the bulk glass was completed, we sent the bulk samples to Laval University in Canada, where the fabrication of the thin films and waveguide structures took place. Right after the film and waveguide samples were created, they were sent back to us, where, once again, we conducted a Raman study to investigate any differences between the films and the bulk glass. In this case, the Raman analysis was conducted using Micro-Raman (backscattering geometry) and Waveguide Raman spectroscopy (90° scattering geometry). Here we demonstrate, for the first time to our knowledge, the use of near-infrared (NIR) waveguide Raman spectroscopy to investigate the microstructure of chalcogenide thin films. This integrated optical technique is extremely powerful in the microstructural analysis of thin film devices due to the combination of good molecular specificity and high sensitivity. The Raman spectra depict microstructural differences between As2S3 films, fibers, and bulk glasses. In the ternary compounds, these microstructural differences are less observable. In chalcogen-rich glasses, the vibrational spectra reveal the preferential formation of homopolar Se-Se and S-S bonds. In those compositions, where Se-Se bonds are observed, high nonlinear optical coefficients have been measured. Near-infrared Raman spectroscopy of photoinduced and annealed structures also allows to identify specific bonding changes which accompany the aging process.
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Bachelor of Science (B.S.)
College of Arts and Sciences
Arts and Sciences -- Dissertations, Academic;Dissertations, Academic -- Arts and Sciences
Length of Campus-only Access
Honors in the Major Thesis
Rivero, Clara A., "Structural characterization of As-S-Se glasses for waveguide applications using near-infrared raman spectroscopy" (2001). HIM 1990-2015. 285.