@article{Hosseini_Javaheri_Jahangiri_Hamidi_Latifi_2023, title={Improving the terahertz collection efficiency based on impedance matching in spintronic THz emitters}, volume={18}, url={https://oiccpress.com/journal-of-theoretical-and-applied-physics/article/improving-the-terahertz-collection-efficiency-based-on-impedance-matching-in-spintronic-thz-emitters/}, DOI={10.57647/J.JTAP.2024.1801.10}, abstractNote={We study the improvement of terahertz collection efficiency in a THz-TDS system based on a spintronic THz emitter, by exploring the effect of substrate impedance matching. This improvement is obtained by properly coupling a hyper-hemispherical lens fabricated from suitable THz materials to a non-magnetic (NM)|ferromagnetic (FM)|substrate emitter structure. The emitter is a Ni|Pt bilayer film coated on a MgO substrate. The refractive index and the dispersion properties of the substrate are adjusted according to the impedance matching conditions and consequently for the maximum THz collection efficiency by a photoconductive antenna (PCA). By comparing various substrates, including MgO, Al2O3, SiO2, and polyethylene terephthalate (PET), our results reveal that the power of the THz radiation collected from the Ni|Pt|MgO with the hyper-hemispherical Si-lens coupler is 64.5 times larger than that from the Ni|Pt|MgO without the lens coupler. A PET substrate in direct contact with a hyper-hemispherical Teflon-lens could be a favorable choice for improved collection efficiency of STE-induced THz radiation, in the absence of Si-lens. These results could be considered useful to achieve the guidelines for scaling the THz radiation power emitted from the spintronic THz emitter according to the employed substrate and hyper-hemispherical lens.}, number={1}, journal={Journal of Theoretical and Applied Physics}, publisher={OICC Press}, author={Hosseini, Seyedeh Maryam and Javaheri, Amin Sadraei and Jahangiri, Fazel and Hamidi, Seyedeh Mehri and Latifi, Hamid}, year={2023}, month={Dec.}, keywords={THz-TDS, Spintronic THz emitter, Index-matching, Hyper-Hemispherical lens} }