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Ti-diffused near-stoichiometric(NS) LiTaO 3 multimode planar waveguide was fabricated by diffusion of Ti-film coated onto a congruent LiTaO 3 substrate and post Li-rich vapor transport equilibration process. The crystalline phase in the Ti-diffused layer was analyzed by powder x-ray diffraction and the Li 2 O-content was evaluated from the measured birefringence. The Ti-concentration profile was analyzed by secondary ion mass spectrometry. The modes guided in the planar waveguide were characterized by prism-coupling technique. The refractive index profile was constructed from the measured mode indices, and correlated with the Ti-concentration profile. The results show that the waveguide retains the LiTaO 3 phase and is in an NS composition environment. Both the refractive index and Ti-concentration follow Gaussian profile. The extraordinary and ordinary index change profiles are almost same, implying that the electric field profile of the mode guided in the NS Ti:LiTaO 3 waveguide would be polarization-insensitive. The ordinary and extraordinary index changes and the Ti-concentration follow a similar exponential relationship with a power index ∼1.3. Comparison shows that the Ti:LiTaO 3 waveguide shows considerable differences from the Ti:LiNbO 3 in Ti diffusivity, index change profile and its relation to Ti-concentration, and polarization dependence of guided mode. [ABSTRACT FROM AUTHOR]

Dispersion relation is established for Er(NbO 3) 3 phosphor, which is an excellent candidate for optical thermometry based on thermal effect of Er3+ fluorescence intensity ratio. To achieve it, Er(NbO 3) 3 phosphor was dispersed into α-bromonaphthalene liquid to form a suspension. Then, refractive index values of the suspension were measured at wavelengths 473, 589.3, 632.8, 980, 1311 and 1553 nm by dropping it onto a plastic sheet. Subsequently, refractive indices of the Er(NbO 3) 3 phosphor were evaluated from these measured index values using Maxwell-Garnett relation. Finally, based on these Er(NbO 3) 3 index values, which have an error 0.03, a three-oscillator Sellmeier equation that considers contributions from Nb–O group, plasmons in far UV regime and phonons in infrared region is established. In parallel, a Cauchy dispersion equation is also established. Both equations can well fit the experimental data and the refractive indices predicted by the two equations can be regarded as identical within the error 0.03. Refractive indices of Er(NbO 3) 3 phosphor at different wavelengths ranging from 473 to 1553 nm have been obtained from the index values measured from an α-bromonaphthalene mixture suspended with Er(NbO 3) 3 phosphor grains. A three-oscillator Sellmeier equation n2(λ) = B UV - B IR λ2 + B 3 /(λ 3 −2-λ−2) is proposed that considers the contributions from plasmons in far UV, phonons in infrared region and the Nb–O group. A Cauchy dispersion equation n(λ) = A + B/λ2 + C/λ4 + D/λ6 is also attempted to fit the experimental data. The fitting results show that both equations can give accurate prediction of the refractive index value of the Er(NbO 3) 3 phosphor and have an accuracy better than 0.03 satisfying the demand for Judd-Ofelt spectroscopic analysis. Image 1 • Refractive indices of Er(NbO 3) 3 powder were measured at different wavelengths. • A three-oscillator Sellmeier equation n2(λ) = B UV -B IR λ2+B 3 /(λ 3 −2-λ−2) is suggested. • A Cauchy dispersion equation n(λ) = A + B/λ2+C/λ4+D/λ6 is also established. • Both equations give accurate prediction of refractive index value of Er(NbO 3) 3. • Both equations have an accuracy 0.03 satisfying demand for Judd-Ofelt analysis. [ABSTRACT FROM AUTHOR]