A method for manufacturing of a waveguide for guiding an electro-magnetic wave comprising: forming a first waveguide layer, a sacrificial layer and a protection layer on a first wafer, patterning to define a pattern of a first waveguide part and a supporting structure in the first waveguide layer; exposing the sacrificial layer on the first waveguide part while the protection layer still covers the sacrificial layer on the supporting structure; removing the sacrificial layer on the first waveguide part; removing the protection layer; bonding a second wafer to the sacrificial layer of the first wafer such that a second waveguide part is supported by the supporting structure and a gap corresponding to the thickness of the sacrificial layer is formed between the first and second waveguide parts.