Femtosecond continuum spectroscopy and Kramers-Kronig relations

We have developed a nonlinear spectrophotometer that can measure nondegenerate spectra from 1.7 /spl mu/m in the IR to 200 nm in the UV. Dual diode arrays for the IR and visible are used to measure the spectral changes in the transmittance against a reference beam. The pump beam is the output of a regeneratively amplified, frequency doubled, femtosecond fiber ring oscillator.