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Figure 1

From: Mixed regime of light-matter interaction revealed by phase sensitive measurements of the dynamical Franz-Keldysh effect

Figure 1

The Franz-Keldysh effect.

(a) The unperturbed absorption edge of a semiconductor (black curve) displays, in a uniform electric field, below-gap absorption and above-gap oscillations (red curve). Insert: a static electric field tilts the bands enhancing sub-gap tunnelling leading to below-gap absorption. (b) Dynamical Franz-Keldysh effect detected by pump-probe THz spectroscopy. The bands are tilted with a non-trivial phase relation with the applied ac fields. Right: sketch of the two limits of the FKE, that is static for infinite γ and dynamic for γ close to 1 (see text).

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