2D materials for hybrid laser wavelength tuning

This research project focuses on the improvement of Photo-Thermal Spectroscopy and Quartz Enhanced Photo-Acoustic Spectroscopy systems that require precise control over the operating wavelength of the optical source while maintaining constant output power. To achieve this, a new approach using two-dimensional materials such as graphene is proposed, which offers low driving voltage and power, tunability, and reconfigurability for advanced sensing technology. The main objective of this research is to design, fabricate, and characterize tunable devices based on silicon-nitride resonant cavities operating at 1.55 microns, integrated with monolayer or bilayer graphene sheets. By tuning a graphene capacitor integrated within an optical device, it becomes possible to manipulate the wavelength and phase characteristics of the resonance or the wavelength generated. The ability to vary the graphene Fermi level will enable efficient control and engineering of the complex refractive index of the resonant mode across a broad range of operating conditions, leading to reconfigurable graphene-based devices that surpass current state-ofthe- art technologies. The fabrication of the device was carried out at the Tyndall National Institute and using graphene deposition and its transfer - at the Apulian Graphene Lab. Characterization of the fabricated prototypes was carried out at both Polytechnic University of Bari and Munster Technological University.