(a) Modal dispersion curves for the fundamental symmetric mode of ridge in Si oriented at various angles

(b) Modal dispersion curves for the fundamental antisymmetric mode of ridge in Si oriented at various angles

Figure 11: Modal dispersion curves obtained for the fundamental (a) symmetric and (b) antisymmetric modes in a ridge waveguide oriented at various angles in a Silicon crystal. The velocity of the symmetric mode does not vary with frequency significantly, because this mode closely resembles the dispersionless surface wave.