  We measure and analyze reflection spectra of directly coupled systems of
waveguides and cavities. The observed Fano lines offer insight in the
reflection and coupling processes. Very different from side-coupled systems,
the observed Fano line shape is not caused by the termini of the waveguide, but
the coupling process between the measurement device fiber and the waveguide.
Our experimental results and analytical model show that the Fano parameter that
describes the Fano line shape is very sensitive to the coupling condition. A
movement of the fiber well below the Rayleigh range can lead to a drastic
change of the Fano line shape.
