Spectral processor implemented with hybrid free-space and guided-wave optics and active LCoS modulator

We propose and demonstrate a broadband spectral phase and amplitude modulator for the C-band spectrum based on a hybrid free-space and guided-wave optics arrangement. A combination of arrayed waveguide grating (AWG) with a Fourier lens disperses the signal in the lens¿ back focal plane. Modulation of the spectrum is subsequently performed with a spatial phase modulator working in reflection. In this work we report for the first time the use of liquid crystal on silicon (LCoS) based phase modulator in the hybrid arrangement. Usage of this device enables phase control on a pixel-by-pixel basis. In this manner we can modulate the phase of every pixel by applying the suitable voltage on it. An amplitude modulation can also be achieved by applying a phase interference effect at the LCoS plane. The combination of spectral phase and amplitude modulation along the LCoS array enables numerous ways of signal manipulations.