Figure 1.

(a) First plateau of the current–voltage characteristics for the SSL with 50 identical periods. (b) Zoom of the region of self-oscillations that appear as a supercritical Hopf bifurcation and end at a SNIPER. $V_d$ is the voltage at which the frequency of the oscillations drop to lower values. For $V_{dc}>V_d$, the high electric field domains move throughout the SSL and reach the collector contact. Current traces and the corresponding density plots of the electric field for (c) $V_{dc}=0.26\mathrm{V}$ (just after the Hopf bifurcation) and (d) $V_{dc}=0.29\mathrm{V}$ (just before the SNIPER bifurcation). Light and dark tones correspond to low and high field values, respectively.