Polarization analysis of THz radiation using a wire grid polarizer and ZnTe crystal

Objectives. Terahertz time domain spectroscopy (THz-TDS) is currently a promising research method in pharmacology and medicine due to the high sensitivity of terahertz radiation to the chemical composition and molecular structure of organic compounds. However, due to the chirality of many biomolecules, their analysis is performed by THz irradiation with circular dichroism. In particular, circular dichroism of THz radiation allows the study of “soft” vibrational movements of biomolecules with different chiralities. Therefore, when studying such biological materials, accurate control of THz radiation parameters is essential. The paper describes a method for characterizing THz radiation polarization on the example of a black phosphorus source material.

Methods. The analysis of polarization parameters of THz radiation experimentally obtained by THz-TDS and using terahertz polarizers was performed by mathematical modeling of the interaction between THz radiation and a ZnTe crystal as a detector.

Results. Two schemes of terahertz spectroscopy with the ZnTe crystal as the detector were discussed in detail. The polarization parameters were determined using one or two wire-grid THz polarizers. An expression for approximating the dependences of the peak-to-peak amplitude of THz radiation on the rotation angle of the wire-grid THz polarizer for these cases was derived. The impact of the terahertz electric field intensity value on the shape of polarization dependences was considered. The rotation angle of the polarization ellipse of THz radiation emitted by the surface of a bulk-layered black phosphorus crystal illuminated by femtosecond laser pulses was determined.

Conclusions. The amplitude of the THz radiation electric field intensity begins to impact the shape of polarization dependences when its value becomes comparable to or exceeds 40 kV/cm.

1. Cui H., Zhang X.B., Yang P., Su J.F., Wei X.Y., Guo Y.H. Spectral characteristic of single layer graphene via terahertz time domain spectroscopy. Optik (Stuttg). 2015;126(14): 1362–1365. https://doi.org/10.1016/j.ijleo.2015.03.032

2. Maamar N., Lazoul M., Latreche F.Y., Trache D., Coutaz J.L. Terahertz time-domain spectroscopy characterization of nitrocellulose in transmission and reflection configurations. Optik (Stuttg). 2020;224:165711. https://doi.org/10.1016/j.ijleo.2020.165711

3. Tu S., Wang Z., Liang G., Zhang W., Tang Y., She Y., Yi C., Bi X. A novel approach to discriminate transgenic soybean seeds based on terahertz spectroscopy. Optik (Stuttg). 2021;242:167089. https://doi.org/10.1016/j.ijleo.2021.167089

4. Tan N.Y., Zeitler J.A. Probing phase transitions in simvastatin with terahertz time-domain spectroscopy. Mol. Pharm. 2015;12(3):810–815. https://doi.org/10.1021/mp500649q

5. Ho L., Pepper M., Taday P. Signatures and fingerprints. Nat. Photonics. 2008;2(9):541–543. https://doi.org/10.1038/nphoton.2008.174

6. Wang W.N., Wang G., Zhang Y. Low-frequency vibrational modes of glutamine. Chinese Phys. B. 2011;20(12):123301. https://doi.org/10.1088/1674-1056/20/12/123301

7. Du S.Q., Li H., Xie L., Chen L., Peng Y., Zhu Y.M., Li H., Dong P., Wang J.T. Vibrational frequencies of anti-diabetic drug studied by terahertz time-domain spectroscopy. Appl. Phys. Lett. 2012;100(14):143702. https://doi.org/10.1063/1.3700808

8. Andersen J., Heimdal J., Mahler D.W., Nelander B., Wugt Larsen R. Communication: THz absorption spectrum of the CO2–H2O complex: Observation and assignment of intermolecular van der Waals vibrations. J. Chem. Phys. 2014;140(9):091103. https://doi.org/10.1063/1.4867901

9. Walther M., Plochocka P., Fischer B., Helm H., Uhd Jepsen P. Collective vibrational modes in biological molecules investigated by terahertz time-domain spectroscopy. Biopolymers. 2002;67(4–5):310–313. https://doi.org/10.1002/bip.10106

10. Tonouchi M. Cutting-edge terahertz technology. Nat. Photonics. 2007;1:97–105. https://doi.org/10.1038/nphoton.2007.3

11. Dadap J.I., Shan J., Heinz T.F. Circularly polarized light in the single-cycle limit: the nature of highly polychromatic radiation of defined polarization. Opt. Express. 2009;17(9):7431–7439. https://doi.org/10.1364/OE.17.007431

12. Yang X., Zhao X., Yang K., Liu Y., Liu Y., Fu W., et al. Biomedical applications of terahertz spectroscopy and imaging. Trends Biotechnol. 2016;34(10):810–824. https://doi.org/10.1016/j.tibtech.2016.04.008

13. Buryakov A., Zainullin F., Khusyanov D., Abdulaev D., Nozdrin V., Mishina E. Generation of elliptically polarized terahertz radiation from black phosphorus crystallites. Opt. Eng. 2021;60(08):082013. https://doi.org/10.1117/1.OE.60.8.082013

14. Khusyainov D., Ovcharenko S., Gaponov M., Buryakov A., Klimov A., Tiercelin N., Pernod P., Nozdrin V., Mishina E., Sigov A., Preobrazhensky V. Polarization control of THz emission using spin-reorientation transition in spintronic heterostructure. Sci. Rep. 2021;11(1):697. https://doi.org/10.1038/s41598-020-80781-5

15. Huang Y., Yartsev A., Guan S., Zhu L., Zhao Q., Yao Z., He C.,Zhang L., Bai J., Luo J., Xu X. Hidden spin polarization in the centrosymmetric MoS2 crystal revealed via elliptically polarized terahertz emission. Phys. Rev. B. 2020;102(8):085205. https://doi.org/10.1103/PhysRevB.102.085205

16. Kovalev S.P., Kitaeva G.K. Two alternative approaches to electro-optical detection of terahertz pulses. JETP Lett. 2011;94(2):91–96. https://doi.org/10.1134/S0021364011140074

17. Deng B., Tran V., Xie Y., Jiang H., Li C., Guo Q., Wang X., Tian H., Koester S. J., Wang H., Cha J. J., Xia Q., Yang L., Xia F. Efficient electrical control of thin-film black phosphorus bandgap. Nat. Commun. 2017;8:14474. https://doi.org/10.1038/ncomms14474

18. Long G., Maryenko D., Shen J., Xu S., Hou J., Wu Z., Wong W.K., Han T., Lin J., Cai Y., Lortz R., Wang N. Achieving ultrahigh carrier mobility in two-dimensional hole gas of black phosphorus. Nano Lett. 2016;16(12): 7768–7773. https://doi.org/10.1021/acs.nanolett.6b03951

19. Chen X., Wu Y., Wu Z., Han Y., Xu S., Wang L., Ye W., Han T., He Y., Cai Y., Wang N. High-quality sandwiched black phosphorus heterostructure and its quantum oscillations. Nat. Commun. 2015;6:7315. https://doi.org/10.1038/ncomms8315

20. Hossain F.M., Murch G.E., Belova I.V., Turner B.D. Electronic, optical and bonding properties of CaCO3 calcite. Solid State Commun. 2009;149(29–30): 1201–1203. https://doi.org/10.1016/j.ssc.2009.04.026

21. Soykan C., Kart S.Ö. Structural, mechanical and electronic properties of ZnTe polymorphs under pressure. J. Alloys Compd. 2012;529:148–157. https://doi.org/10.1016/j.jallcom.2012.02.170

22. Yariv A., Yeh P. Photonics: optical electronics in modern communications. Oxford University Press; 2007. 836 p.