Spectral profile of the two-photon absorption coefficients in CaF[sub 2] and BaF[sub 2].

Two-photon absorption spectra due to the valence excitons in CaF[sub 2] and BaF[sub 2] have been measured using the second harmonic of the output of a XeCl-excimer-laser pumped dye laser as a light source. The band gap energies of CaF[sub 2] and BaF[sub 2] are obtained as 11.8 and 10.6 eV at 298 K, respectively. The two-photon absorption coefficient β in the spectral region below the 2P exciton is expressed by an exponential function of the photon energy in both crystals. The values of β at the 2P exciton peak are about 2×10[sup -9] cm/W for CaF[sub 2] and 3×10[sup -9] cm/W for BaF[sub 2]. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]