  Anisotropy of spin-orbit interaction (SOI) is studied for a single uncapped
InAs self-assembled quantum dot (SAQD) holding just a few electrons. The SOI
energy is evaluated from anti-crossing or SOI induced hybridization between the
ground and excited states with opposite spins. The magnetic angular dependence
of the SOI energy falls on an absolute cosine function for azimuthal rotation,
and a cosine-like function for tilting rotation. The SOI energy is even
quenched at a specific rotation. These angular dependence compare well to
calculation of Rashba SOI in a two-dimensional harmonic potential.
