Additional waves and Fabry‐Perot interference of photoexcitons (polaritons) in thin II–VI crystals

Abstract

Within the frame work of Pekar's model for a spatially dispersive, bounded medium, optical spectra of thin crystals, reported by us recently, are analyzed, showing a structure due to the interference of additional waves and the Pabry-Perot structure deviating markedly from the one expected in the classical case in the neighbourhood of exciton resonances.A comparison of the experimental reflectivity with that obtained numerically provides values for all physical parameters defining dispersion and damping of the photoexcitons. Some additional experimental results for excitons in thin crystals are reported: evidence for the induced surface wave, an effect of the forbidden exciton, etc. HaK HaMM J7Xe COO6waJlOCb, I3 MHTep@epeHUMOHHbIX CIIeHTpaX TOHKMX KPII-CTaJIJIOB B OKpeCTHOCTH 3KCHTOHHbIX pe30HaHCOB IIpORBJKRIOTCfi ABa TMIIa OCO-6eHHOCTefi: CTpYKTYpa, BO3HHKaH)II~aR 113-38 MHTCpl$epeHqMII n06aBOxIHbIX BOJlH II CTpyIcTypa CDaBpn-nepo, 3HacWITeJlLH0 OTXM~aIOwaXCH OT TOB, I-iOTOpaH OifcE1.1-PYIOTCH B paMKaX MOaeJIII neKapa OrpaHH4eHKKOt CpenbK C IIpOCTpaHCTBCHHOfi naeTcx B KnaccmYecKoM cnyqae. €3 Hamoxwet3 pa6oTe ~T M cnei-FTpbI a~an113k1nncnepcneii. Cpameme s~c n e p r n~e~~a n~,~o r o EI pacqwawioro cnempa n03BOJ-ReT HafiTm ~H~Y~H M R

Exchange Splitting of Zero-Dimensional Exciton Levels

“…For CdSe according to Ref. [6] we have ħωTF N 0.12 meV, ħωLT 0.95 meV and it follows that the ratio between the second (nonanalytic) and first (analytic) terms amounts about 3.…”

Excitonic Polaritons in Transverse Magnetic Fields

“…In the Voigt geometry we observed an effect of magnetic field inversion [1,2], consisting of a difference between the reflectivity spectra for magnetic fields +B and −B in opposite directions (see Fig. 3a, b).…”

“…This effect was strongest in the region in which heavy and light exciton transitions coexist and is apparently caused by mixing of light and heavy excitons by the magnetic field. This effect due to magnetic field inversion was studied for the first time in [1,2] and also in [13]. It was described by terms in the exciton Hamiltonian such as ∝ K × B, which mix optically active 1S and optically inactive 2P exciton states [14].…”

“…In contrast, wide quantum wells provide a unique opportunity to study excitonic states with nonzero wave vectors, i.e. excitons in motion [1,2]. Due to size quantization, features of exciton states with nonzero wave vector emerge in optical spectra [3].…”

Study of exciton-polariton modes in nanocrystalline thin films of CuCl using reflectance spectroscopy

“…The modeling algorithm calculates the reflection coefficient as a function of photon energy and enables determination of the relative electric field strengths due to different photon and polariton modes in various regions of the structure. Fabry-Perot effects 13 in our thin film samples are quite prominent and must be considered to accurately model the experimental data, especially in spectral regions away from exciton peak positions. The effect of the DLs at the film interface is shown to be minimal (due to the small excitonic Bohr radius and correspondingly small DL thickness and the larger surface roughness of our samples which will tend to average out any effects).…”