Two-photon absorption coefficients in ultraviolet-grade optical fibers
are measured in the range of 219-260 nm. A frequency-doubled tunable
dye laser is used as the light source. The two-photon absorption coeff
icient increases exponentially with an increase in the photon energy.
The exciton peak does not appear in the spectrum. Theoretical values a
re calculated by the Keldysh formula and compared with the experimenta
l results.