The discussion revolves around the characteristics of Silicon Nitride Waveguides (Si3N4), specifically addressing whether these waveguides have a cladding and the implications for the evanescent field and mode field when light is coupled into the waveguide. The scope includes theoretical and conceptual aspects of waveguide design and light propagation.
Participants express differing views on the presence of cladding in Silicon Nitride Waveguides, and there is ongoing clarification regarding the nature of the fields produced when light is coupled into the waveguide. The discussion remains unresolved regarding the specifics of these interactions.
Limitations include potential assumptions about the definitions of evanescent fields and mode fields, as well as the dependence on specific conditions such as beam size and angular diameter.
If the question is in context of on-chip optical waveguide, answer is "likely no cladding". Some processes have polyimide coating over top silicon nitride, but polyimide option is uncommon.Sciencestd said:
Evanescent as long as beam angular diameter is much smaller than full reflection angle.Sciencestd said:
Narrow beams will produce only evanescent field above waveguide; unfocused (i.e. on-chip LED) will produce propagation modes above waveguide.Sciencestd said: