Coupling of a surface grating to a structurally chiral volume grating

The problem of the coupling of a surface dielectric grating to a structurally chiral volume grating is formulated and solved. The volume grating is a chiral sculptured thin film, which exhibits the circular Bragg phenomenon in distinct wavelength regimes. Two distinct interactions are involved: (i) those of linearly polarized and circularly polarized modes, and (ii) those of nonspecular modes with the specular Bragg phenomenons. Numerical studies show that the circular Bragg phenomenon is virtually immune to the presence of the surface grating. Hence, chiral STF filters can be diffraction-coupled to other optical elements.