A WSS device in which a VIPA is used as a spectral disperser. In an example embodiment, the VIPA is configured to produce two or more diffraction orders on the LCOS micro-display of the WSS device. The LCOS micro-display is configurable to independently process light corresponding to different diffraction orders. For example, the LCOS micro-display may be used to implement: (i) optical-signal switching by applying different relative phase shifts to light of different diffraction orders to cause constructive interference at a selected one of the optical ports of the WSS device; (ii) optical-signal splitting by steering light of different diffraction orders to at least two different selected optical ports of the WSS device; and (iii) controllable optical-signal attenuation by applying different relative phase shifts to different diffraction orders to control the relative degree of constructive and destructive interference at a selected one of the optical ports of the WSS device.