Analysis of highly sensitive biosensor for glucose based on a one-dimensional photonic crystal nanocavity

Abstract

A one-dimensional (1-D) photonic crystal (PhC) composed of multilayer thin films having the form (Si / Air)9 is investigated. The selection of Si and air is because their use as a material platform provides the ability to fabricate sensors with other photonic devices on a single chip. We design a biosensor concept that uses an optical resonance in a 1-D silicon PhC with an air defect, which is theoretically studied for refractive index (RI) sensing in the infrared wavelength region (700 to 1900 nm). A similar crystal with a defect layer by changing the dielectric constant in different orders is also studied. A method is presented to maximize the sensitivity of the biosensor and to obtain a very narrow bandwidth cavity mode for good biosensor resolution. We optimized the thickness of the air defect layer in the PhCs on both sides of the nanocavity and show that a high sensitivity value of 1118 nm/refractive index unit (RIU) with a detection limit of 0.001 RIU, which proves the ability of the design to produce biosensor PhC. This optical biosensor has a very much higher sensitivity and simpler structure compared to other PhC biosensors reported previously.