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.

Abstract Chalcogenide glasses and films are excellent candidates for near-infrared guiding configurations in opto-e]ectronics due to the ir high transmission. Their photosensitivity allows waveguide creation by standard lithography or one- and two-photon writing. The near-infrared Raman spectra of a series of As-S(Se) glasses are analyzed using spectral deconvolution and correlated with the molecular structure. Contributions due to As­ (S,Se)3 pyramjdal subunits as well as homopolar Se-Se and S-S bonds are determined. Photoinduced molecular changes in waveguide structures are probed by Raman scattering employing guided mode excitation. A new approach is demonstrated to optically interrogate composite layers where a chalocogenide waveguide provides the substrate and the guiding layer for a biomolecular film whose Raman spectrum is desired. Hydrophilic chalcogenide surfaces were prepared by exposure to 0 ₂ plasma and characterized by XPS spectroscopy. Thin layers of the photo-active protein bacteriorhodopsin were deposited on As₂S3 waveguides and observed by scanning electron and atomic force microscopy. The evanescent wave excited near-infrared Raman spectrum is measured in-situ providing a molecular probe of the chromophore and the light-adaptedstate. This novel technique offers potential for protein monolayer characterization and bio-sensors.