Jessica Afalla

University of Tsukuba · Graduate School of Pure and Applied Sciences

We demonstrate that terahertz radiation can be generated from titanium-diffused magnesium oxide-doped lithium niobate optical strip waveguides when pumped by a single laser source with a wavelength of 1.55 μm. Titanium-in-diffusion was performed on a magnesium oxide-doped lithium niobate substrate by the deposition of titanium in a 40-µm wide strip...

Epitaxial low temperature grown GaAs (LT-GaAs) on silicon (LT-GaAs/Si) has the potential for terahertz (THz) photoconductive antenna applications. However, crystalline, optical and electrical properties of heteroepitaxial grown LT-GaAs/Si can be very different from those grown on semi-insulating GaAs substrates (reference). In this study, we invest...

Epitaxial low temperature grown GaAs (LT-GaAs) on silicon (LT-GaAs/Si) has the potential for terahertz (THz) photoconductive antenna applications. However, crystalline, optical and electrical properties of heteroepitaxial grown LT-GaAs/Si can be very different from those grown on semi-insulating GaAs substrates ("reference"). In this study, we inves...

We present the implementation of an efficient terahertz (THz) photoconductive antenna (PCA) emitter design that utilizes high mobility carriers in the two-dimensional electron gas (2DEG) of a modulation-doped heterostructure (MDH). The PCA design is fabricated with recessed metal electrodes in direct contact with the 2DEG region of the MDH. We comp...

We present threefold enhancement of terahertz emission from silicon nanowire (SiNW)-coated gallium-arsenide photoconductive antenna over its uncoated counterpart. The enhancement is attributed to the increased photoabsorption, and possibly additional photoconductive pathways induced by the SiNWs.

***This is a peer-reviewed paper published in the JOURNAL OF THE JAPAN SOCIETY OF INFRARED SCIENCE AND TECHNOLOGY, Vol. 29, Issue No. 2, pp. 57-62 (February 2020).*** A spintronic bilayer structure, which consists of 2-nm Fe and 3-nm Pt epitaxial grown on 500-µm MgO substrate, was investigated as a terahertz (THz) source for different optical pump...

Illuminating metallic spintronic heterostructures with ultrafast laser pulses can generate terahertz (THz) radiation due to spin current-to-charge current conversion. Such metallic spintronic heterostructures are essentially ultrathin ferromagnetic and non-ferromagnetic metallic layers stacked on appropriate substrates. They are particularly attrac...

Carrier dynamics and photoconductivity in epitaxial-grown low-temperature GaAs on nominal and vicinal Si(1 0 0) substrates ('LT-GaAs/Si') were studied to predict their actual performance as THz photoconductive antenna (PCA) detectors. An optical-pump terahertz-probe technique was used to obtain the transmittance, carrier lifetime and photoconductiv...

Spintronic heterostructures are emerging and interesting emitters of terahertz (THz) radiation. In the past, THz emission of spintronic layers is by an antenna-free approach. In this paper, we report on THz wave generation of a diabolo-shaped Fe/Pt spintronic antenna using a 780-nm wavelength pump beam from a femtosecond laser. THz emission amplitu...

Terahertz (THz) generation of spintronic heterostructures is becoming popular due to broader THz bandwidth with tunable emission amplitude and polarization [1-2]. These heterostructures typically consist of stacks of ferromagnetic (FM) and nonmagnetic (NM) thin films which generate THz radiation either by the inverse spin-Hall [3] or the interface...