A photonic processing module (100) comprises a high index-contrast waveguide device comprising a substrate (102), a first layer (104) disposed on the substrate having a first refractive index, and a relatively thin second layer (106) disposed on the first layer. The second layer has a second refractive index providing a high index-contrast with the first layer, and the device includes at least one thin-ridge waveguide element (108) formed in the second layer which supports a guided mode in a longitudinal direction. An optical input port (110) is configured to direct an input beam into a slab mode of the second layer, the beam being directed to propagate at a predetermined angle θ to the longitudinal direction of the thin-ridge waveguide element. The angle θ is associated with a resonant coupling between the slab mode of the second layer and the guided mode of the thin-ridge waveguide element. An output beam is thus generated when the input beam includes one or more optical components corresponding with the resonant coupling. An optical output port (112) is configured to receive the output beam.