Wavelength Domain Multiplexed fiber specklegram sensor

In this work, a low-cost WDM interrogation system has been proposed and experimentally tested to obtain two independent channels of a fiber specklegram sensor. Two lasers of different wavelengths have been launched into two multimode Polymer Optical Fibers (POFs) and then combined through a coupler before their interrogation using a RBG camera. By analyzing each color of the video sequence, the two fiber channels can be independently obtained. Besides, the speckle sensitivity has been also studied by analyzing different properties of speckle patterns such as their contrast or the speckle size. The achieved results help to the development of new fiber specklegram sensors by allowing a direct comparison between two specklegrams of different properties.