  An optical Fano resonance, which is caused by birefringence control rather
than frequency selection, is discovered. Such birefringence-induced Fano
resonance comes with fast-switching radiation. The resonance condition
$\varepsilon_t< 1/\varepsilon_r$ is revealed and a tiny perturbation in
birefringence is found to result in a giant switch in the principal light pole
induced near surface plasmon resonance. The loss and size effects upon the Fano
resonance have been studied Fano resonance is still pronounced, even if the
loss and size of the object increase. The evolutions of the radiation patterns
and energy singularities illustrate clearly the sensitive dependence of Fano
resonance upon the birefringence.
