High resolution spectroscopy of excitons in Cu₂O

Abstract

The lowest ortho-and paraexcitons of Cu 2 O are studied by high-resolution spectroscopy. After a detailed description of the experimental setup, the quadrupole polariton is extended to a two-oscillator resonance. As an example, the group velocity of the M = ±1 orthoexciton components in a magnetic field of 0.1 T is measured and fitted to a two-oscillator model with f (oscillator strength) as the only fit parameter. The paraexciton resonance is measured in a magnetic field of 10 T. Its oscillator strength is by almost a factor 200 lower than the oscillator strength of the orthoexciton.

THz quantum optics with dark excitons in Cu2O: from stimulated emission to nonlinear population control

“…2(b)] with unusually long lifetimes in the μs to ms regime [5,7,14,[31][32][33][34]. Central cell corrections dramatically enhance the effective mass of 1s excitons (m 1s = 2.61 m e ) with respect to all higher bound states (m 2p = 1.68 m e ) [33].…”

“…The semiconductor Cu 2 O forms a particularly well-defined laboratory for these experiments. Since excitons in Cu 2 O are counted among the most serious candidates for Bose Einstein condensation [2,5], the system has been extensively investigated by photoluminescence [5], Raman [31], mid-infrared [14], and highresolution spectroscopy [32,33]. The visible absorption spectrum of our naturally grown single-crystal is dominated by a series of sharp lines originating from the 2p, 3p, 4p, and 5p excitons of the yellow series, below the pair continuum [ Fig.…”

Anisotropic effective mass of orthoexcitons in Cu2O

“…For convenience we introduce x =hck/n (eV) instead of the wave number k (m −1 ) (Ref. 18) where n is the refractive index (n = 2.94) 12 and x 0 = E 0 = 2.032 78 eV is the resonance energy at k 0 . The E i values are calculated from the known anisotropy parameters 7 ( 3 = −1.3 μeV, 5 = 2 μeV, and Q = 5 μeV) as shown in the inset of Fig.…”

Femtosecond THz studies of intra‐excitonic transitions

“…Since excitons in Cu 2 O are counted among the most serious candidates for Bose Einstein condensation [8], the system has been extensively investigated by photoluminescence [8], Raman [36], mid-infrared [37], and high-resolution spectroscopy [38]. The visible absorption spectrum of our 330-μm-thick, naturally grown single-crystal is dominated by a series of sharp lines originating from the 2p, 3p, 4p, and 5p excitons of the yellow series, below the pair continuum (see Fig.…”