Design of an On-Chip Absorption Spectrometer Using Optofluidic Slotted Photonic Crystal Structures

The authors propose a tunable slow-light slotted photonic crystal (PhC) waveguide, without nanoscale variation of structure parameters, applicable in on-chip absorption spectroscopy. The main feature of this structure is that the enhanced electrical field is strongly localized in an air slot with nanometer width due to slow-light properties of a slot mode. In the proposed structure, the slow-light region of the slot mode can be controlled using a selective infiltration of a PhC waveguide. The numerical calculation reveals that an enhancement factor, $\gamma$, of 20 can be achieved.