Ultracompact plasmonic sensor with graphene-based silicon reflector

In this paper, we investigate a monolayer graphene placed on a doped-silicon grating numerically and studied the dependence of its transmission spectra on the geometrical parameters of the grating. A stop-band with great tunability in the mid-infrared region of the transmission spectra are obtained in a much more compact structure size compared to a traditional fiber Bragg grating (FBG). In addition, by inserting a defect into the center of the structure, we introduce a phase shift of π phase shift into the field, leading to an open window in the stop-band transmission spectra. With the good tunability and compact size, our proposed structure can be utilized as graphene-based ultra-compact and highly sensitive plasmonic senors for potential applications.