Destruction and stabilization of the electromagnetic transparency of a semiconductor superlattice

Electron Bloch oscillations and electromagnetic transparency of semiconductor superlattices in multi-frequency electric fields

“…A stationary current is established in the SL after the time τ and its spectral constitution can be significantly different from that of ac BOs, especially in the presence of the static component [8,13,18]. In contrast to the DL, the SIT occurs only after time τ from the field application and can exist for a long time (mach larger than τ) [17,19] and, consequently, has more chances to be observed experimentally. Beyond the τ-approximation, the values of the field at which the DL and the SIT occur can be quite different [8,9,17].…”

“…In contrast to the DL, the SIT occurs only after time τ from the field application and can exist for a long time (mach larger than τ) [17,19] and, consequently, has more chances to be observed experimentally. Beyond the τ-approximation, the values of the field at which the DL and the SIT occur can be quite different [8,9,17]. Moreover, at non-periodic biharmonic field, the DL exists and the SIT does not [17].…”

“…Self-induced transparency (SIT) means that at specific magnitudes of high-frequency field the macroscopic electron polarization in the SL becomes small (even vanishes in the limit of rare collisions) and the SL behaves almost like a dielectric with the permittivity of the crystal lattice and relatively small nonlinear absorption. If the SL becomes transparent by means of some applied harmonic field, it can also be transparent for the other harmonic field [9,15,17]. This effect is called induced transparency (IT).…”

“…This effect is called induced transparency (IT). Selective transparency (ST) means consequent vanishing of specific harmonics of the excited current with changing of the harmonic field magnitude [8,17]. The mechanisms of the transparency appearing for the SLs with the sinusoidal miniband have been carefully studied in Refs.…”

“…Beyond the τ-approximation, the values of the field at which the DL and the SIT occur can be quite different [8,9,17]. Moreover, at non-periodic biharmonic field, the DL exists and the SIT does not [17]. Furthermore, it was shown [17,19] that the transparent state of the SLs with the sinusoidal minband in the harmonic field is unstable with respect to both quasistatic and high-frequency perturbations (in particular, the SL in the SIT state has absolute negative conductivity (ANC) [14,20] and resonant negative dissipative conductivity at frequencies close to the harmonics of the external field [15,17,19]) and, accordingly, can be observed only in the SLs with low electron densities and only in transient processes or under the pulsed external field with the pulse duration much larger than τ.…”