FEM Simulations of Rod-Type Photonic Crystal Slabs as Resonant Microsystems for Optical Gas Sensors

C. Kraeh, and H. Hedler
Siemens AG, Munich
Munich, Germany

We are developing a solid state gas sensor that combines a small form factor with the high sensitivity of optical gas detection. The gas sensor is based on an optical resonant microsystem that is penetrated by gas molecules. This microsystem consists of an array of vertical rods in air forming a photonic crystal.

Light propagates through the photonic crystal along a line defect waveguide. For gas detection the resonance frequency of the waveguide has to overlap with the absorption wavelength of the gas. We are using the RF module of Comsol Multiphysics to simulate light propagation through the photonic crystal waveguide. Special attention is drawn to the enhancement of light-gas interaction by a reduced group velocity of the waveguide modes.