Fig.1

(a) Schematic diagrams of metagratings with a complex unit cell; (b) The four diffraction orders are supported by a metagrating of $ d=\lambda /\sqrt{2} $ at an angle of incidence, ${\theta }_{i}$ =45° "

Fig.2

(a) A schematic diagram illustrating a variation of complex unit cell configurations, achieved by moving the position of the small rod by a distance $\delta{d }$ ; (b) A heatmap illustrating the transmissivity of the negative first order transmitted wave, T–1, with varying radii of the small rod and large rod (r and R, respectively) for different complex unit cell configurations, the fixed $\delta{d}$ value is different in each heatmap, with $ {\theta }_{i}= $ 45°, $ d=1\;096\;\mathrm{n}\mathrm{m} $ , and $ \lambda =1\;550\;\mathrm{n}\mathrm{m} $ "

Fig.3

(a) The transmissivity of the negative first order transmitted wave, T–1, as a function of the change in position of the small rod in the complex unit cell, $ \delta d $ ; (b), (c) The distribution of magnetic field intensity is illustrated for a Gaussian beam striking a metagrating with a complex unit cell with (b) $\delta{d }$ = 20 nm, and (c) $\delta{d }$ = 106 nm "

Fig.4

The relationship between transmissivity of the negative first order transmitted wave, T–1, of the metagratings and frequency. The relationship is investigated for four metagratings, each with different complex unit cells consisting of two touching rods of radii R = 260 nm and r = 120 nm "