Broadband optical absorption in a two-dimensional electron gas in the presence of spin-orbit interaction and high magnetic fields

We examine the selection rules for electron-photon interaction in a two-dimensional electron gas (2DEG) in the presence of the Rashba spin-orbit interaction (RSOI) and quantizing magnetic fields. In such a case, new channels open up for electronic transition accompanied by the absorption of photons. As a result, two absorption peaks and a broadband absorption spectrum can be observed for high-mobility samples at relatively high magnetic fields. We find that electronic transitions between the neighboring Landau levels within the same spin orientation are the main channels for optical absorption in a spin-split 2DEG.