#ESS2205: Tilted Fiber Bragg Grating Plasmonic Hydrogen Sensors Supervisor: Michael Fried

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Overview: The increase in interest in hydrogen as a renewable fuel source has created a demand for hydrogen sensors. Optical fiber sensors are inherently safe in an explosive environment, and thus provide an advantage over electrical sensors. A promising sensing method is the use of plasmonics to sense small changes in the refractive index of metals as they form metal-hydrides under hydrogen exposure. Tilted Fiber Bragg Gratings (TFBGs) have gained attention as a sensing platform due to their simple fabrication, small size, selfreferencing for strain and temperature, and remote sensing capabilities. Phase matching between the core and cladding modes occurs at discrete wavelengths, and thus a spectral ‘comb’ of cladding modes is excited. These cladding modes can excite surface plasmons in a metal layer coated on the fiber cladding. By tracking small shifts in wavelength or change in power of specific cladding modes, the change in refractive index can be detected. This project aims to build a low cost method of interrogating the fiber sensors that doesn’t rely on an expensive optical spectrum analyzer.

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Goals and tasks: The first goal is to assemble an interrogation system composed of a chirped laser diode, photo-detector and digital oscilloscope. The second task is to write a program to determine the peak position from the data. Finally tests to determine the capabilities of the system, and tune the setup for optimal performance.

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Skills:

• knowledge in optics and electronics.
• ability to analyze the data with programming language of your choice.
• ability to work and problem solve independently.
• students interested in continuing with a master project on optical fiber hydrogen sensors in the fall may be given priority