  We report the development of a monolithic, mechanically tunable waveguide
platform based on the flexible polymer polydimethyl siloxane (PDMS). Such
devices preserve single mode guiding across a wide range of linear geometric
distortions. This enables the realization of directional couplers with tunable
splitting ratios via elastic deformation of the host chip. We fabricated
several devices of this type, and verified their operation over a range of
wavelengths, with access to the full range of input/output ratios. The low cost
and relative ease of fabrication of these devices via a modified imprint
lithographic technique make them an attractive platform for investigation of
large scale optical random walks and related optical phenomena.
