Compact and portable QEPAS gas sensing systems

THz modulators based on electrolyte-gated graphene structures

In the framework of the European Graphene Flagship, our group has developed efficient and compact THz modulators based on electrolyte-gated graphene structures and Salisbury-like quarter wavelength reflection cavities, working in the 2-5 THz range. By integrating the modulators with a THz quantum cascade laser frequency comb, in an external cavity configuration, fine-tuning of the intermode beatnote frequency is also demonstrated. This opens intriguing perspectives for short pulse generation, phase-locking, frequency tuning/chirping, phase modulation, and metrological referencing. Structure of electrolyte gated graphene-based THz modulators: - Substrate:Rigid (silicon wafer, glass), or flexible (kapton) - Back reflector gold electrode:prepared by e-beam evaporation - Salisbury mirror cavity of thickness 10-20 μm Membrane (Polycarbonate, polypropylene & optical tissue) soaked with ionic liquid or Ionic Gel - Top window: Single layer graphene on quartz