Infrared spectroscopy is used to study the doping and temperature dependence of the intragap absorption in the ferromagnetic semiconductor Ga12xMnxAs, from a paramagnetic, x50.017 sample to a heavily doped, x50.079 sample. Transmission and reflectance measurements coupled with a Kramers-Kronig analysis allow us to determine the optical constants of the thin films. All ferromagnetic samples show...

Orbital angular momentum (OAM) spectrum diagnosis is a fundamental building block for diverse OAM-based systems. Among others, the simple on-axis interferometric measurement can retrieve amplitude and phase information of complex OAM spectra in few shots. Yet, its single-shot retrieval remains elusive, due to signal–signal beat interference inherent measurement. Here, we introduce concept Krame...

Wave propagation in a one-dimensional random medium with shortor long-range correlations is analyzed. Multiple scattering is studied in the regime where the fluctuations of the medium parameters are small and the propagation distance is large. In this regime pulse propagation is characterized by a random time shift described in terms of a standard or fractional Brownian motion and a determinist...

In this paper, we study theoretically a pump–probe model for the Kramers–Kronig (KK) relations during laser operation. A solution of laser equations reveals that the dispersion profile of a saturated laser gain medium is non-analytical at the boundary between the lasing and the non-lasing spectral region. Such a non-analyticity cannot be explained in terms of the KK relations. In order to inter...

A generic physical situation is considered where Im Π, the imaginary part of polarization operator (generalized susceptibility), can be measured on a finite interval and the high frequency asymptotics (up to a few orders) of Π can be calculated theoretically. In such a case, it is desirable to derive an equivalent form of the Kramers-Kronig dispersion relation, the so-called sum rule, in which ...