We demonstrate that nonlinear wave interaction between fundamental solitons with surrounding dispersive waves in a nonlinear optical fiber leads to intermittent giant waves with all typical signatures of rogue waves. The underlying physical mechanism is based on the concept of the so-called optical event horizon and is naturally given in the supercontinuum generation process. Moreover, one can use this mechanism in a deterministic way to make an all-optical control of light pulses possible. This is a natural way to optical transistors