  We describe an all-optical scheme for spin manipulation in the ground-state
triplet of the negatively charged nitrogen-vacancy (NV) center in diamond.
Virtual optical excitation from the 3A_2 ground state into the 3E excited state
allows for spin rotations by virtue of the spin-spin interaction in the
two-fold orbitally degenerate excited state. We derive an effective Hamiltonian
for optically induced spin-flip transitions within the ground state spin
triplet due to off-resonant optical pumping. Furthermore, we investigate the
spin qubit formed by the Zeeman sub-levels with spin projection m_S = 0 and m_S
= -1 along the NV axis around the ground state level anticrossing with regard
to full optical control of the electron spin.
