Fig. 1. Schematic of the GMR subwavelength structure, where I₀ and I_t correspond to the incident and transmitted light intensities, respectively.

Fig. 2. Simulated results under the specific condition of d_a = 100 nm, w = 500 nm, and p = 3.4 µm: (a) simulated transmission spectra of the designed structure with various waveguide layer thicknesses between 0.2 µm and 0.8 µm and (b) FWHM and peak transmittance of the filters with different waveguide thicknesses.

Fig. 3. Electric field distributions in the GMR structure at the resonant wavelength with various waveguide layer thicknesses: (a) d_wg = 0.2 µm, (b) d_wg = 0.5 µm, and (c) d_wg = 0.8 µm under the specific condition of d_a = 100 nm, w = 500 nm, and p = 3.4 µm.

Fig. 4. Simulated transmission spectra of filters with varying grating periods under the specific condition of d_a= 100 nm, w = 500 nm, and d_wg = 0.5 µm.

Fig. 5. Simulated transmission spectra of the filters with varying (a) slit widths w and (b) grating thicknesses d_a under the specific condition of p = 3.4 µm and d_wg = 0.5 µm.

Fig. 6. Two methods towards consistency in filtering performance with varying (a) slit widths and (b) gradient waveguide thicknesses.