A Metal-Assisted Silicon Slot Waveguide for Highly Sensitive Gas Detection

A metal-assisted silicon slot waveguide for highly sensitive gas detection is proposed. To show the superiority of the proposed structure, the optical confinement factor in the gas region and the sensitivity are theoretically investigated using the 2-D vector finite element method. Numerical results show that the proposed structure can achieve a strong light confinement in the gas region compared with the conventional slot waveguide. The maximal optical confinement factor of 85% is obtained in the proposed structure, which is approximately 2.5 times larger than the conventional slot waveguide. Additionally, the results show that the proposed structure has a large sensitivity compared with the conventional slot waveguide. Finally, a ring resonator based on the proposed structure is analyzed to evaluate the Q factor and to increase the validity of results obtained by 2-D simulation.