In our paper [1], the theoretical analysis and optimization of subwavelength grating (SWG) structures were performed by the rigorous coupled-wave analysis (RCWA) method using a commercial software (DiffractMOD 3.1, Rsoft Design Group). In the DiffractMOD 3.1 software, for the three-dimensional (3D) modeling of SWGs, the geometric parameters such as height (H_SWG), radius (R_SWG), and order of taper (O_T) are numerically defined for convenience. To understand and describe the geometries and their parameters in the 3D model designed by the DiffractMOD 3.1software, we needed to analytically define the geometry expression of SWG structures using the Cartesian coordinate system by the scalar-valued function of three variables, f(x,y,z). The Eq. (1) was devised to analytically fit and express the numerically defined 3D geometry by the DiffractMOD 3.1 software and to understand the effect of the geometric parameters. However, we found a mistake in Eq. (1) for the geometry expression of SWGs. As can be confirmed in Fig. 1(a) , this equation should be represented as:

 

Fig. 1 (a) General geometry of Si SWGs expressed by the equation of the tapered cone.

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Accordingly, we also correct the Fig. 1(a).

The authors regret this mistake, which does not affect any numerical results presented in our publication [1] because they were obtained by the 3D model designed in the DiffractMOD 3.1 software as shown in Fig. 1(b), but not one in Eq. (1).