realization of a wavelength

shifter based on cascaded second-order processes

in the organic molecular crystal N-(4-

nitropheny1)-L-prolinol (NPP).’ In our experiment,

a pump pulse p at frequency wp and

a signal pulse s at w, - wp interact to generate

the frequency-shifted signal fat wf= 20, - w,.

Defining q as the ratio of the energy off at the

output to sat the input, the goal is to achieve q

= 1 with a moderate pump intensity.