中国物理B ›› 2025, Vol. 34 ›› Issue (9): 94204-094204.doi: 10.1088/1674-1056/add903

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Abnormal focal length increase of terajet generated in reflection mode

Yu-Jing Yang(杨育静)1, Jiang-Tao Qin(秦江涛)1, De-Long Zhang(张德龙)1,†, Sai-Dong Xue(薛赛东)2,‡, and Ning Yuan(袁宁)3,§   

  1. 1 Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-Electronics Engineering, Key Laboratory of Optoelectronic Information Technology (Ministry of Education), and Key Laboratory of Micro-Opto-Electro-Mechanical Systems (MOEMS) Technology (Ministry of Education), Tianjin University, Tianjin 300072, China;
    2 College of Electrical and Electronic Engineering, Anhui Science and Technology University, Bengbu 233030, China;
    3 Tianjin Sino-German University of Applied Sciences, Tianjin 300350, China
  • 收稿日期:2025-03-03 修回日期:2025-05-02 接受日期:2025-05-15 出版日期:2025-08-21 发布日期:2025-09-09
  • 通讯作者: De-Long Zhang, Sai-Dong Xue, Ning Yuan E-mail:dlzhang@tju.edu.cn;xuesaidong@hotmail.com;yuanning0321@163.com
  • 基金资助:
    terajet|reflection mode|air hollow|focal length|phase singularity

Abnormal focal length increase of terajet generated in reflection mode

Yu-Jing Yang(杨育静)1, Jiang-Tao Qin(秦江涛)1, De-Long Zhang(张德龙)1,†, Sai-Dong Xue(薛赛东)2,‡, and Ning Yuan(袁宁)3,§   

  1. 1 Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-Electronics Engineering, Key Laboratory of Optoelectronic Information Technology (Ministry of Education), and Key Laboratory of Micro-Opto-Electro-Mechanical Systems (MOEMS) Technology (Ministry of Education), Tianjin University, Tianjin 300072, China;
    2 College of Electrical and Electronic Engineering, Anhui Science and Technology University, Bengbu 233030, China;
    3 Tianjin Sino-German University of Applied Sciences, Tianjin 300350, China
  • Received:2025-03-03 Revised:2025-05-02 Accepted:2025-05-15 Online:2025-08-21 Published:2025-09-09
  • Contact: De-Long Zhang, Sai-Dong Xue, Ning Yuan E-mail:dlzhang@tju.edu.cn;xuesaidong@hotmail.com;yuanning0321@163.com
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 61875148), the Key Awards Program of Cultivating Outstanding Innovative Postgraduates in Arts and Sciences of Tianjin University (Grant No. C1-2022- 002), the Talent Project of Anhui Science and Technology University (Grant No. DQYJ202304), the University-Level Research Project of Tianjin Sino–German University of Applied Sciences (Grant No. zdkt2018-007), China Association for Science and Technology Young Talent Support Project Doctoral Special Program, and the National High-level University Scholarship Program for Graduate Students of China Scholarship Council (Grant No. 202406250166).

摘要: We report an interesting and abnormal electromagnetic phenomenon with regard to a terajet (TJ) that is generated in a reflection mode, which is realized by placing a dielectric scatterer onto a metal reflection plate. We show that the introduction of an air hollow into metal reflection plate beneath the scatterer does not induce an expected decrease but an abnormal increase of focal length of the TJ by as much as more than three times. This abnormal phenomenon takes place in case that the air hollow is shallow and there exists a critical hollow depth for a given lateral size of air hollow. Larger than the critical depth, the phenomenon no longer occurs. It is explained from viewpoints of both ray optics in terms of role of relative portion of central waves in TJ formation and electromagnetic field theory with regard to hollow-induced phase singularities.

关键词: terajet, reflection mode, air hollow, focal length, phase singularity

Abstract: We report an interesting and abnormal electromagnetic phenomenon with regard to a terajet (TJ) that is generated in a reflection mode, which is realized by placing a dielectric scatterer onto a metal reflection plate. We show that the introduction of an air hollow into metal reflection plate beneath the scatterer does not induce an expected decrease but an abnormal increase of focal length of the TJ by as much as more than three times. This abnormal phenomenon takes place in case that the air hollow is shallow and there exists a critical hollow depth for a given lateral size of air hollow. Larger than the critical depth, the phenomenon no longer occurs. It is explained from viewpoints of both ray optics in terms of role of relative portion of central waves in TJ formation and electromagnetic field theory with regard to hollow-induced phase singularities.

Key words: terajet, reflection mode, air hollow, focal length, phase singularity

中图分类号:  (Wave propagation, transmission and absorption)

  • 42.25.Bs
42.25.Fx (Diffraction and scattering) 42.50.St (Nonclassical interferometry, subwavelength lithography) 42.25.Hz (Interference)