Isolas in the three-photon optical excitation of a single cyclotron electron.

We show that sufficiently strong laser beams with two frequencies differing by a cyclotron frequency of a free electron can give rise to strong cyclotron excitation with prohibited and allowed cyclotron orbits as well as to an optical Stark shift. This is due to a combination of relativistic effects and results in multiple isolated branches of excited motion (isolas). The formation of the first three-photon isola, when lambda(cyclotron) approximately 2 mm and lambda(laser) approximately 10 microm, can be observed with the laser power as low as congruent with 10 mW.