Dy. Tang et al., OPTICAL FRICTION WHEELS - ASYMMETRIC SEEDING OF THE TEM(01) HYBRID MODE OF A HENE LASER, Optics communications, 105(5-6), 1994, pp. 320-324
It is shown that a helical wave laser injected by a helical wave emits
the helicity of the injected wave for coaxial alignment of laser beam
and injection beam; but the opposite helicity for a lateral displacem
ent of laser- and injection beam. This corresponds to the motion of a
mechanical rotating disk coupled to another disk by friction.