Quantitative Raman Spectroscopy of Homogeneous Molecular Profiles in Optical Waveguides via Direct Measurement

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Abstract
Quantitative measurements of Raman scattering from three-layer asymmetric slab dielectric waveguides made of organic macromolecular materials have been obtained from homogeneous distributions of scatterers as a function of mode by direct measurement of all mode-dependent quantities. For low-order modes, precision of the Raman intensity is limited to ∼5% by uncertainty in the measurement of the coupling coefficient, γ; while for high-order modes, precision was limited at the same level by uncertainty in the integrated electric field due to film-thickness variations. Observation of Raman instead of Rayleigh scatter vs. distance in the waveguide allowed measurement of the optical loss function, α, to be made down to 0.2 dB/cm with less than 1% uncertainty, so it is never the limiting factor.