Scientific Reports (Aug 2017)

A broadband reflective-type half-wave plate employing optical feedbacks

  • Gaochao Zhou,
  • Bo Zhu,
  • Junming Zhao,
  • Guanghao Zhu,
  • Biaobing Jin,
  • Yijun Feng,
  • Lin Kang,
  • Weiwei Xu,
  • Jian Chen,
  • Peiheng Wu

DOI
https://doi.org/10.1038/s41598-017-09561-y
Journal volume & issue
Vol. 7, no. 1
pp. 1 – 12

Abstract

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Abstract We propose and demonstrate a type of a broadband half-wave plate that operates in the reflective mode. It consists of a metal grating embedded in a dielectric slab and placed on top of a grounded metal surface. We theoretically show that owing to the optical feedback effect which originates from the wave reflections at the air-dielectric interface, the proposed half-wave plate exhibits a broadened and flattened response when comparing to the case where the feedback effect is absent. Such a prediction is validated using both numerical and experimental works carried out on a half-wave plate designed at 10 GHz. Moreover, our theoretical analysis also reveals that the half-wave plate has an interesting feature of broad angular response. Taking advantage of these features, we experimentally demonstrate that the proposed device can function as a freely tunable linear polarization converter with polarization conversion residues less than −20 dB in a wide frequency band, under the condition that the incident angle is as large as 45 degrees.