A terahertz (THz) saturable absorber has been created using printable graphene inks produced by liquid phase exfoliation (LPE) and deposited by transfer coating and ink jet printing. Such an absorber could enable the development of ultrafast lasers in the THz range. Such lasers could be useful in applications where short time scale excitation of specific transitions is important, such as time-resolved spectroscopy of gasses and molecules.
Researchers at CNR-Istituto Nanoscienze used LPE of graphite to formulate both a water-based ink and a surfactant-free, low boiling point, ethanol-based ink. They demonstrated THz saturable absorption from films produced by both vacuum filtration and inkjet printing.
Through the combination of open-aperture z-scan experiments, transport analysis of field effect transistors (FETs) embedding these inks, and Fourier transform infrared (FTIR) spectroscopy, researchers showed a transparency modulation almost one order of magnitude larger than that reported to date for THz frequencies. These results could open the way for the integration of graphene with existing sources to realize ultrafast, mode-locked lasers and passive ultrafast components across the THz frequency range.
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Source: Photonics Media