Figure 5
Gain spectrums in cases of a small scale [i, u, l] (black curves) and a full scale [i, u, l, h1, h2] (red curves) in both designs at 50 K (a1, c1) and 300 K (b1, d1). The exact transitions between subbands pairs are labeled by different color arrows in the spectrums. The gain is marked as g+, and the absorption is marked as g−. The exact absorption area near the depopulation energy is enlarged in plots (a2, b2).
