Analysis of the Performance of WDM-CDM Bragg Grating Interrogation System With High-Contrast Grating VCSEL

This article shows a novel approach for Bragg gratings interrogation, based on vertical-cavity surface-emitting laser with high-contrast grating cavity. It is shown that with such a light source, one may achieve simultaneous wavelength sweeping together with output light intensity modulation enabled by a single element. In turn, it allows for designing a two-dimensional (time and wavelength) Bragg grating interrogation scheme. The article consists of analytical deliberations that determine the limiting factors of such an interrogation unit, i.e. interrogation speed and size of the sensing network for given Bragg grating reflectivity, expressed in the form of signal-to-noise ratio. Moreover, an experimental and numerical proof of concept of the sensing unit consisting of fiber Bragg grating sensors with an interrogation speed of 1 kHz and the use of code division multiplexing is also presented.