Fig. 4

a Schematic of the BIM waveguide with introduced silicon ribbons. The width of each silicon ribbon is d, and the distance between the ribbons is L. b Numerical (blue balls) and CMT fitted (red curve) transmission spectra of the proposed structure where g = 1 μm, d = 5 μm, and L = 120 μm. c–e Magnetic field distributions (|H_z|²) of at the incident frequencies of 1.56 (c), 1.90 (d), and 2.22 THz (e)