Work

Observation of terahertz nonlinear absorption activity in Al 2 O 3

Year: 2024

Type: article

Abstract: We investigate the terahertz (THz) nonlinear absorption characteristics in a thin Al 2 O 3 crystal using nonlinear THz spectroscopy. A THz saturable absorption performance with a high modulation depth (27.5%) and a relatively low saturable intensity (6.99 µJ/cm 2 ) of Al 2 O 3 is revealed, covering the THz spectrum from 0.1 to 8 THz. The inevitable presence of oxygen vacancies and impurities in Al 2 O 3 single crystal results in the existence of free electrons within the conduction band. The transmission enhancement can be described by the change of the mobility of electrons due to intervalley scattering induced by THz pulses, based on first-principles calculations. Therefore, Al 2 O 3 crystals have promising application potential in mode-locked devices for directly delivering broadband ultrashort THz pulses.

Source: Optics Express

DOI: 10.1364/oe.537621