MEMS-based metamaterial grating waveguide for tunable optical attenuator and modulator applications

Abstract

We present a metamaterial grating waveguide (MGW) for tunable optical attenuator and modulator applications in the infrared (IR) wavelength range, which is composed of sixty periodically one-dimensional gold (Au) nanograting structures on silicon (Si) nanograting waveguide. The first thirty Au nanograting structures along the opposite propagation direction of the guided wave are divided equally into three groups. By elevating the first group (G1) of Au nanograting structures from the Si waveguide surface, the transmission intensity of MGW decreases from 1.0 to 0.3 at the wavelength of 1.278 μm. While elevating the second (G2) and third (G3) groups of Au nanograting structures from the Si waveguide surface, the transmission intensities can be attenuated from 1.0 to 0.3 and 1.0 to 0.4, respectively. For the elevation of G3, the transmission intensity at a specific wavelength can be switched between 0 and 0.8. Furthermore, MGW shows a linear blue-shifting relationship of resonant wavelengths and incident angles between 8° and 20° with a correction coefficient of 0.9991. The resonances of MGW also exhibit blue-shifting characteristics by increasing the environmental refraction index. This proposed design of MGW provides a useful approach for variable optical attenuating, optical switching, wavelength tuning, and sensing applications in the IR spectrum range.