Spectrally dispersed light from a fine resolution waveguide grating router (WGR) of 25-GHz free spectral range that radiates to free space is spatially filtered at  1 GHz optical resolution and 50 MHz spectral addressability using a liquid crystal on Silicon (LCoS) spatial light modulator (SLM). Fabrication imperfections leading to phase errors on the 32 waveguide arms of the WGR are corrected using a UV pulsed laser to inscribe permanent optical path changes to the waveguides. WGR phase errors are permanently trimmed waveguide-by-waveguide with an excimer laser by inducing stress in the glass cladding above the waveguide for coarse setting and using the photosensitivity effect for fine setting. The WGR was then mated with an LCoS SLM located at the Fourier plane to form a photonic spectral processor, for arbitrary spectral amplitude and phase manipulations.

We present here the work performed in the EU-funded flexible optical cross-connect (FOX-C) project, which investigates and develops new flexible optical switching solutions with ultra-fine spectral granularity. Thanks to high spectral resolution filtering elements, the sub-channel content can be dropped from or added to a super-channel, offering high flexibility to optical transport networks through the fine adaptability of the network resources to the traffic demands. For the first time, the FOX-C solutions developed in the project are investigated here and evaluated experimentally. Their efficiency is demonstrated over two high spectral efficiency modulation schemes, namely multi-band orthogonal frequency division multiplexing (MB-OFDM) and Nyquist WDM (N-WDM) formats. Finally, in order to demonstrate the relevance of the FOX-C node concepts, a networking study comparing the economic advantages of the FOX-C optical aggregation solution versus the electronic one is performed.