Reconfigurable all-diffractive optical filters using phase-only spatial light modulators

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 us to obtain the desired spectrum along the optical axis and, in the second one, which is based on a generalized spectrometer, the desired spectrum is found outside of the optical axis. Experimental results show good agreement with the theory and indicate the validity of this technique.