Optical Arbitrary Waveform Processing of Over 100 Spatial Channels for Optical Performance Monitoring

We developed an optical processing platform that handles over 100 space-division-multiplexed signals in the C-band. The device consists of free-space optics based on liquid crystal on silicon (LCOS) with a waveguide frontend. Thanks to the holographic wavefront modulation by the LCOS spatial light modulator, the device arbitrarily manipulates the optical amplitude and phase in the space and spectral domains simultaneously. This ability enables us to create various optical processing functions such as tunable wavelength filtering, variable optical attenuation, and flexible delay line interferometry with arbitrary spatial and wavelength channel dependence. These functions are highly suitable for large-scale optical performance monitoring (OPM). As an application, we demonstrate OPM for 100 spatial channels over the C-band. The constructed OPM can monitor not only the power spectrum but also the optical signal-to-noise ratio (OSNR) by setting different LCOS phase patterns. We achieved channel power monitoring and OSNR monitoring with 1.8- and 1.9-dB accuracy over 100 spatial channels.