Efficiency of core light injection from sources in the cladding: bulk distribution

The behavior of the power efficiency of an optical fiber with bulk distribution of sources in its cladding is analyzed. Marcuse's (1988) results for weakly guiding cylindrical fibers with fluorescent sources uniformly distributed in the cladding are confirmed for the bulk distribution case. It is found that power efficiency increases with wavelength and with difference in refractive indices. A new independent variable for the bulk distribution is found, and it is shown that the power efficiency does not always increase with the V number.