Hollow Core Waveguide Sensor Array Based on a Macroporous Silicon Membrane Structure

In this paper, we introduce a liquid core microsensor array based on a macroporous silicon membrane structure. Simple oxidation on a macroporous silicon structure forms reflecting mirrors on the pore sidewalls and creates optical resonances in each pore that acts as a hollow core. When light propagates through a pore filled with a liquid, the optical resonance characteristics formed by the reflecting mirrors can be utilized to examine the interaction of light and a target fluid within the pore. Theoretical design and experimental demonstrations are performed. A fabricated refractive index sensor based on the proposed structure shows a sensitivity of around 3116 nm/RIU with more than 10 dB extinction ratio. Considering that a macroporous silicon structure consists of thousands of arrayed pores in a small dimension and each pore can be treated as a single optofluidic sensor, this approach promises new arrayed sensing capabilities that are well beyond the merits offered by the current hollow core waveguide sensors.