  We demonstrate a reconfigurable optical filter implemented using a phase-only
two-dimensional liquid crystal on silicon spatial light modulator. To achieve
this we utilize two different approaches leading to two different
configurations in the modulator. The first one, based on a spatially patterned
diffractive lens permits to obtain the desired spectrum along the optical axis
and, in the second one, based on a generalized spectrometer, it is found
outside of the optical axis. Experimental results show good agreement with the
theory and indicate the validity of this technique.
