Fig. 3: Transient response of polarized optical transitions in Te nanosheet.

a, b A series of selected TR spectra (blue lines) recorded at different pump-probe delay times for both \(E \bot c\) and \(E||c\) polarizations. Dashed red lines are model fits of each corresponding spectrum. c, d Moduli of each corresponding fit for both polarizations. Vertical dashed gray lines are guides to the eye to indicate the systematic shift of peak position. e Transition energies \(E_1^ \bot\), \(E_1^{||}\), and \(E_2^{||}\) extracted from the fits and plotted as a function of delay for both polarizations. Error bars are estimated from the least square fitting procedure. While the \(E_1^ \bot\) remains mostly stable over a long delay, the \(E_1^{||}\), and \(E_2^{||}\) undergo gradual blue and redshifts as delay progresses before they remain steady after ~30 ps. The inset shows the time evolution of anisotropic spectral shifts, as quantified by \(E_1^{||} - E_1^ \bot\) and \(E_2^{||} - E_1^ \bot\) for fundamental and higher energy band-gap anisotropy and \(E_2^{||} - E_1^{||}\) for the gap between uppermost VBs excluding the doping induced Fermi energy shift. Superimposed dashed lines on each curve are exponential fits for a guide to the eye. The shaded region is shown to indicate the static region. f Ground-state and photoinduced band structure (note exaggerated energy scales) around the H-point near the band gap, showing photoinduced lifting \({\mathrm{{\Delta}}}E_{lift}\) of the \(H_6^{CB}\) band and narrowing of the gap \({\mathrm{{\Delta}}}E_{sp}\) between the uppermost VBs. The involved optical transitions are indicated by vertical arrows.