Figure 1

(a) Schematic diagram of the experimental setup for optical 2DFT spectroscopy. The incoming laser pulses are focused in the sample by the lens $f_1$. The box is reconstructed by the lens $f_2$ and the TFWM signal is heterodyne detected with the reference (Ref) beam. (b) Level scheme for the heavy- and light-hole states in GaAs quantum wells. The dashed (solid) arrows represent ${\sigma }^{-}$ (${\sigma }^{+}$) circular polarized light. (c) Level scheme for the heavy- and light-hole excitons and biexcitons in GaAs quantum wells. The 2-exciton states include bound (biexciton) states shown as lines and unbound states indicated by the shaded areas.Reuse & Permissions

Figure 2

2D two-quantum spectra of GaAs quantum wells at different polarizations. (a) Experimental spectra obtained using cross-circular (${\sigma }^{-}{\sigma }^{+}{\sigma }^{+}$) polarization and (b) using co-circular (${\sigma }^{+}{\sigma }^{+}{\sigma }^{+}$) polarization. The laser excitation shown above with the absorbance spectra is resonant with HX energy; therefore, only the HX peak can be observed. $E_{\mathrm{HX}}$ is the heavy-hole exciton energy, and $E_B$ is the biexciton binding energy. (c) and (d) show simulations using the same polarizations.Reuse & Permissions

Figure 3

Experimental 2D two-quantum spectra of GaAs quantum wells when both excitons are excited. (a) Spectrum obtained using cross-circular (${\sigma }^{-}{\sigma }^{+}{\sigma }^{+}$) polarization and (b) using co-circular (${\sigma }^{+}{\sigma }^{+}{\sigma }^{+}$) polarization. Laser excitation shown above with the absorption spectrum.Reuse & Permissions