Beam splitter and combiner based on Bloch oscillations in spatially   modulated waveguide arrays
  We numerically investigate the light beam propagation in periodic waveguide arrays which are elaborately modulated with certain structures. We find that the light beam may split, coalesce, deflect, and be localized during propagation in these spatially modulated waveguide arrays. All the phenomena originate from Bloch oscillations, and supply possible method for fabricating on-chip beam splitters and beam combiners. 
Yiqi Zhang, Milivoj R. Beli\'c, Weiping Zhong, Feng Wen, Yang Guo, Yao   Guo, Keqing Lu, and Yanpeng Zhang
physics.optics