Spatial beam transformer for wavelength selective switch consisting of silica-based planar lightwave circuit

We propose a spatial beam transformer (SBT) for a wavelength selective switch, which is monolithically integrated on a silica-based planar lightwave circuit (PLC). The PLC-integrated SBT has advantages such as freedom from precise alignment and the elimination of expensive bulk optics. In addition, the aspect ratio can be freely designed simply by redesigning the layout of the SBT without adding any other optical components. We successfully tuned the aspect ratio from 7.9 to 87.5 simply by changing the PLC layout.