Power density of the evanescent field in the vicinity of a tapered fiber

The power density in the vicinity of a tapered fiber is calculated, with the vectorial model of step-index circular waveguides. For the fundamental ${\mathrm{HE}}_{11}$ mode carrying a power of 1 Watt, we show that it is possible to obtain theoretical densities in the range of ${10}^8 \mathrm{W}/{\mathrm{cm}}^2$ at the fiber surface. The promising use of such intense evanescent fields as “atomic mirrors” is considered, and the feasibility of these guides is investigated.