Theory of nonlinear optical spectroscopy of electron spin coherence in quantum dots

We study in theory the generation and detection of electron spin coherence in nonlinear optical spectroscopy of semiconductor quantum dots doped with single electrons. In third-order differential transmission spectra, the inverse width of the ultranarrow peak at degenerate pump and probe frequencies gives the longitudinal spin relaxation time (T-1), and that of the Stokes and anti-Stokes spin resonances gives the spin dephasing time including the inhomogeneous broadening (T-2(*)). The transverse spin relaxation time excluding the inhomogeneous broadening effect (T-2) can be measured by the inverse width of ultranarrow hole-burning resonances in fifth-order differential transmission spectra.