New mechanism of saturation absorption in semiconductors

С. В. Гапоненко, Viktor P. Gribkovskii, Lev Zimin +1 more

Kishore K. Kamath, P. R. Vaya

Recently, there has been a renewed interest in the study of absorption spectrum, particularly in the absorption tail region due to the possibility of using the semiconductor etalons for optical bistability. It has been shown that both the dispersive and absorptive optical bistability are possible in semiconductors. However, it is very difficult to obtain absorption saturation in the tail region.1 Therefore, it is very important to study the mechanism of formation, and the density of states distribution in the absorption tail region.

David A. B. Miller, D. S. Chemla, Stefan Schmitt-Rink

We have analyzed theoretically the optical absorption saturation of semiconductor microcrystallites so small that they show strong quantum confinement in all three dimensions [quantum dots (QDs)]. We show that saturation of the lowest energy excited state becomes extremely simple to describe even including excitonic effects. Such QDs exhibit novel physical properties, including very large optical absorption per unit volume, that make QDs very attractive nonlinear media.

Frank Stern

Narkis Tzoar, Joel I. Gersten

R. Colombelli, Mathieu Jeannin

It is well known that optical absorption saturation of intersubband transitions in doped semiconductor quantum wells is independent of the introduced doping in the absence of a cavity. When inserting the system in a resonator, we show that this remains valid only in the weak light-matter coupling regime. In the strong light-matter coupling regime instead, we demonstrate that absorption saturation is no more doping independent and it is instead tailorable. Based on this unified formalism for saturation in weak and strong coupling, we provide designs for semiconductor saturable absorption (SESAM) mirrors and bistable systems operating in the mid-infrared range of the electromagnetic spectrum and with extremely low saturation intensities. Countering intuition, we show that the most suitable region to exploit low saturation intensities is not the ultra-strong coupling regime, but is instead at the onset of strong light-matter coupling.