Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)




Robert S Rogowski


Previous work on efficiency of light injection into the core of a fiber from a thin film and a bulk distribution of sources in the cladding, have made use of the fields of a weakly guiding fiber. This approximation simplifies the analysis of the power efficiency by introducing universal values for the eigenvalues of different fibers with same {dollar}V{dollar}-number, but can not predict accurately the behavior of the injected light into a fiber with arbitrary differences in indices of refraction. We have used the exact field solution in the expressions of the power efficiency, {dollar}P\sb{lcub}\rm eff{rcub}{dollar}, and analyzed its behavior as a function of the remaining parameters. Although more complicated and harder to interpret, our formulas allow us to analyze the power injection efficiency of fibers with arbitrary differences in the indices of refraction. The results obtained are relevant for the design of more efficient optical fiber distributed sensors. The conclusions follow.;We have confirmed weakly guiding results obtained previously. However, we have found that the {dollar}P\sb{lcub}\rm eff{rcub}{dollar} does not always increase with the {dollar}V{dollar}-number but with the difference in the indices of refraction, {dollar}n\sb{lcub}\rm core{rcub} -n\sb{lcub}\rm clad{rcub}{dollar}.;For fixed {dollar}a/\lambda{dollar}, indices of refraction, {dollar}n\sb{lcub}\rm core{rcub}{dollar} and {dollar}n\sb{lcub}\rm clad{rcub}{dollar} and normalized inner and outer radius, {dollar}R\sb{lcub}\rm in{rcub}{dollar} and {dollar}R\sb{lcub}\rm out{rcub}{dollar}, the {dollar}P\sb{lcub}\rm eff{rcub}{dollar} is independent of core radius, {dollar}a{dollar}, and the wavelength, {dollar}\lambda{dollar}. This applies for any uniform cylindrical distribution of cladding sources. This result suggests that {dollar}a/\lambda, R\sb{lcub}\rm in{rcub}{dollar} and {dollar}R\sb{lcub}\rm out{rcub}{dollar} are independent variables.;For the bulk distribution we have found that {dollar}P\sb{lcub}\rm eff{rcub}{dollar} increases with the wavelength, {dollar}\lambda{dollar}, and decreases with the fiber core radius, {dollar}a{dollar}, i.e., it decreases with the {dollar}V{dollar}-number. However, for the thin film, the {dollar}P\sb{lcub}\rm eff{rcub}{dollar} remains almost constant with the wavelength, {dollar}\lambda{dollar}, and fiber core radius, {dollar}a{dollar}.



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