  Optical absorption of circularly polarized light is well known to yield an
electron spin polarization in direct band gap semiconductors. We demonstrate
that electron spins can even be generated with high efficiency by absorption of
linearly polarized light in InGaAs. By changing the incident linear
polarization direction we can selectively excite spins both in polar and
transverse directions. These directions can be identified by the phase during
spin precession using time-resolved Faraday rotation. We show that the spin
orientations do not depend on the crystal axes suggesting an extrinsic
excitation mechanism.
