  We demonstrate experimentally a method of varying the degree of
directionality in laser-induced molecular rotation. To control the ratio
between the number of clockwise and counter-clockwise rotating molecules (with
respect to a fixed laboratory axis), we change the polarization ellipticity of
the laser field of an optical centrifuge. The experimental data, supported by
the numerical simulations, show that the degree of rotational directionality
can be varied in a continuous fashion between unidirectional and bidirectional
rotation. The control can be executed with no significant loss in the total
number of rotating molecules. The technique could be used for studying the
effects of orientation of the molecular angular momentum on molecular
collisions and chemical reactions. It could also be utilized for controlling
magnetic and optical properties of gases, as well as for the enantioselective
detection of chiral molecules.
