Fluid tunable transition from trapping to discrete diffraction in waveguide arrays.

We report on the fluid tunable transition from trapping to discrete diffraction in planar polymer waveguide arrays. A novel optofluidic polymer waveguide array platform was engineered to allow a wavelength dependent transition from a localised state where light is trapped in a defect mode to delocalised state where light is spreading through discrete diffraction. The spectral location of this transition can be controlled through a variation of the fluid's refractive index. The platform is compatible with aqueous solutions, making it an interesting candidate for an integrated refractive index sensor to perform label-free biosensing.