ABSTRACT
In the previous chapters, it was found that prism and grating couplers allow the resonant excitation of leaky modes whose transverse field map in the guiding structure is close to that of guided waves (or surface plasmons). The aim of this chapter is to study the influence of the associated electromagnetic resonances on the linear response of these distributed couplers while taking into account the finite width and the finite duration of the incident beam. This will first be achieved in the stationary regime where electromagnetic resonances will be shown to lead to distortions including null points and m-lines in the near and far fields respectively. The existence of a possible link between the null point and the m-line will be discussed. The case of short pulse excitation will be considered next and the dynamic response of distributed couplers studied. This will allow us to discuss the possibility of exciting short optical pulses in a waveguide by using a distributed coupler. Equation VII. 159c, in its linear form, and eq. VII.159d provide the basis of this analysis.
