Seminar"Polarization properties of terahertz radiation monolithically generated from Bi2Sr2CaCu2O8+δ mesa structures" by Mr. Asem Elarabi, Kyoto University

Speaker: Mr. Asem Elarabi

Affiliation: Department of Electronic Science and Engineering, Kyoto University

Date: Aug 2. 2018

Time: 14:00-15:00

Venue: C016, Lab1

Title: Polarization properties of terahertz radiation monolithically generated from Bi₂Sr₂CaCu₂O_8+δ mesa structures

Abstract:

Continuous-wave terahertz sources made of high-T_c superconducting Bi₂Sr₂CaCu₂O_8+δ (Bi2212) have been extensively studied both experimentally and theoretically since its conception in 2007 [1]. This type of THz sources has a compact size (< 0.01 mm²) with large frequency tunability ranges (1–11 THz), and highly monochromic radiations. Polarization properties of Bi2212 based devices have not been thoroughly investigated [2–4] despite their importance for practical applications. It is known that circularly polarized (CP) electromagnetic wave is achieved in labs by introducing optical devices (e.g., quarter wave plate) into the beam path. Nevertheless, monolithic generation of CP is preferable due to the portability advantage for mobile communications. Generation of CP THz wave from Bi2212 has been numerically suggested in multiple publications [2,3]. In the presented study, we experimentally demonstrate emission of CP THz waves from Bi2212 devices and discuss the polarization properties of the emissions using methods similar to that applied by microstrip patch antennas [6]. The achieved circular polarization states are desigined by using the truncated edge square mesa shape [3,4] and cylindrical mesa shape with notched sides. The axial ratio (AR) representing the polarization state was found to be less than 3 dB in both mesa geometries, which indicates a highly circularly polarized radiation. Evolutions of AR and other polarization parameters provide novel insights to reveal synchronization mechanism of the Bi2212 THz emission.

References

[1]      I. Kakeya and H. Wang, Supercond. Sci. Technol. 29, 73001 (2016).

[2]      H. Asai and S. Kawabata, Appl. Phys. Lett. 110, 132601 (2017).

[3]      A. Elarabi, Y. Yoshioka, M. Tsujimoto, et al., Phys. Procedia 81, 133 (2016).

[4]      A. Elarabi, Y. Yoshioka, M. Tsujimoto, et al., Phys. Rev. Appl. 8, 64034 (2017).

[5]      R. A. Klemm and K. Kadowaki, J. Phys. Condens. Matter 22, 375701 (2010).

[6]      M. Haneishi and Y. Suzuki, in Handb. Microstrip Antennas, Vol. 1, edited by J. R. James and P. S. Hall (IET, 1989), pp. 219–274.

This work has been done in collaboration Y. Yoshioka, S. Fujita, M. Tsujimoto, and

I. Kakeya.