  A pulsed technique for electrons in 2D systems, in some ways analogous to
spin echo in nuclear magnetic resonance, is discussed. We show that a sequence
of optical below-band gap pulses can be used to suppress the electron spin
relaxation due to the D'yakonov-Perel' spin relaxation mechanism. The spin
relaxation time is calculated for several pulse sequences within a Monte Carlo
simulation scheme. The maximum of spin relaxation time as a function of
magnitude/width of the pulses corresponds to $\pi$-pulse. It is important that
even relatively distant pulses efficiently suppress spin relaxation.
