Rethinking the surface of optical waveguides

The interface between the core and the cladding of optical waveguides exhibits a number of physical phenomena that do not occur in the bulk of the material. For this reason, the behavior of nanoscale devices is expected to be conditioned, or even dominated, by the nature of their surfaces. Roughness-induced losses, backscattering and crosstalk between adjacent waveguides, together with surface states absorption impact on the optical and electrical properties of the waveguides must be considered in the design of any integrated optoelectronic device. The detrimental effects and the possibility of their exploitation are carefully reviewed, presenting in particular the ContacLess Integrated Photonic Probe to be used as transparent power monitor.