Jeannin Mathieu, Manceau Jean-Michel, Colombelli Raffaele
Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris-Saclay, 91120 Palaiseau, France.
Phys Rev Lett. 2021 Oct 29;127(18):187401. doi: 10.1103/PhysRevLett.127.187401.
We propose a unified description of intersubband absorption saturation for quantum wells inserted in a resonator, both in the weak and strong light-matter coupling regimes. We demonstrate how absorption saturation can be engineered. In particular, we show that the saturation intensity increases linearly with the doping in the strong coupling regime, while it remains doping independent in weak coupling. Hence, countering intuition, the most suitable region to exploit low saturation intensities is not the ultrastrong coupling regime, but is instead at the onset of the strong light-matter coupling. We further derive explicit conditions for the emergence of bistability. This Letter sets the path toward, as yet, nonexistent ultrafast midinfrared semiconductor saturable absorption mirrors (SESAMs) and bistable systems. As an example, we show how to design a midinfrared SESAM with a 3 orders of magnitude reduction in saturation intensity, down to ≈5 kW cm^{-2}.
我们提出了一种对置于谐振器中的量子阱在弱光与物质耦合和强光与物质耦合两种情况下的子带间吸收饱和的统一描述。我们展示了如何设计吸收饱和。特别地，我们表明在强耦合情况下，饱和强度随掺杂呈线性增加，而在弱耦合情况下它与掺杂无关。因此，与直觉相反，利用低饱和强度的最合适区域不是超强耦合情况，而是强光与物质耦合开始的阶段。我们进一步推导出双稳态出现的明确条件。这封信为目前尚不存在的超快中红外半导体可饱和吸收镜（SESAMs）和双稳态系统指明了方向。例如，我们展示了如何设计一种饱和强度降低3个数量级、低至约5 kW cm⁻²的中红外SESAM。
