Characterization of Nanoscale Systems: From Far-Field Imaging to Optoelectronics in 2D Materials

ABSTRACT

Advances in the characterization of nanoscale systems have significantly deepened our understanding of light-matter interactions. In this seminar, I will begin by presenting a polarization parametric indirect method [1] to image subwavelength scattering information, which reveals additional insights beyond what is possible with conventional far-field microscopy. I will then discuss the harmonic generation in 2D materials, with a particular focus on the third harmonic generation in the Dirac semimetal Cd3As2, often considered as a 3D analogue of graphene [2, 3]. Finally, I will share recent findings on the optoelectronic properties of 2D materials exposed to natural cosmic radiation in space, highlighting the impact of defect-induced effects on their behavior [4].

[1] Kaleem Ullah, Xuefeng Liu, Muhammad Habib and Zhe Shen. Subwavelength Far Field Imaging of Nanoparticles with Parametric Indirect Microscopic Imaging. ACS Photonics, 4, 1388-1397, (2018).

[2] Kaleem Ullah, Yafei Meng, Yi Shi and Fengqiu Wang*, Harmonic Generation in Low Dimensional Materials, Advanced Optical Materials, 10, 7, 2101860 (2022)

[3] Kaleem Ullah, Yafei Meng, Yue Sun, Yunkun Yang, Xiangjing Wang, Anran Wang, Xinran Wang, Faxian Xiu, Yi Shi1 and Fengqiu Wang. Third Harmonic Generation in Dirac Semimetal Cd3As2, Applied Physics Letters, 117, 011102 (2020)

[4] Dun Mao, Lorry Chang, Hwaseob Lee, Anthony Yu, Kaleem Ullah, Bennett Maruca, William Mathaeus, Michael Krainak, Po Dong, Tingyi Gu, Space qualifying silicon photonic modulators and circuits, Science Advances 10, 1, eadi9171 (2023).

BIOGRAPHY

Kaleem Ullah is currently a Postdoctoral Researcher at Stevens Institute of Technology. Before joining Stevens, he held postdoctoral research positions at the University of Delaware and Nanjing University. He earned his Ph.D. in Optical Engineering from the Nanjing University of Science and Technology. His research interests span far-field super-resolution Imaging, metasurfaces, and light-matter interactions in 2D materials.