Slow light (SL) states corresponding to wavelength regions near the bandgap edge of grated structures are known to show strong field enhancement. Such states may be excited efficiently by well-optimised adiabatic transitions in grated structures, e.g., by slowly turning on the modulation depth. To study adiabatic excitations, a detailed research in 1D is performed to obtain insight into the relation between the device parameters and properties like enhancement and modal reflection. The results enable the design of an adiabatic device for efficient excitation of SL states in 1D. The effect of small wavelength variations as well as small fluctuations in the modulation depth of the grating has been investigated.