ABSTRACT
When a light beam with a finite front is reflected or refracted, the reflected and transmitted light does not completely follow the evolution of geometrical optics. In particular, the beam shifts on the order of the wavelength will appear along both the longitudinal and transverse directions. The longitudinal beam shift is called the Goos-Hänchen shift (GH shift), while the transverse beam shift is known as the Imbert-Fedorov shift (IF shift) or the Spin Hall Effect of Light shift (SHEL shift). Accurate measurements of beam shifts in different structures can help us study the light-material interactions and the conversion between the spin and orbital angular momentum. The unique planar crystalline structures of 2D materials bring about a huge influence on the beam shift and introduce new properties. However, the current beam shift measurement methods still have certain limitations for the direct measurement of beam shift in 2D materials. Moreover, experimental studies on mechanically exfoliated 2D materials are still lacking. Recently, we proposed a new technique to measure the beam shift, which is known as the beam shift amplification technique. The resolution of beam shift is as high as 4 nm using this technique, and the spectral information of beam shift can be obtained at the same time. With the help of the beam shift amplification technique, we observed the anomalous GH shift and IF shift in graphene, the anisotropic GH shift in black phosphorus and rhenium disulfide, and the adjustment of the IF shift by the number of molybdenum disulfide layers. Combining supercontinuum light source and beam shift amplification technology, we have successfully observed the GH shift and IF shift spectra of various 2D materials such as graphene and tungsten disulfide, and explored the effects of excitonic properties, energy dispersion and layered structure on the beam shift spectrum.
BIOGRAPHY
Zhibo Liu is a Professor at School of Physics, Nankai University. He received his bachelor’s degree in 2001 and his PhD in 2006 from Nankai University. Prof. Liu is an expert in optical nonlinearity of materials, nonlinear characterization methods, optical properties of 2D materials and their applications. He has published more than 130 peer-reviewed papers, including several in Nano Lett. and Adv. Mater. His papers have over 6000 citations and the highest one has more than 1000 citations. Further, three of his papers are selected as ESI Highly Cited Papers. Prof. Liu received numerous rewards for his pioneering work in nonlinear optics. He was selected as one of the "New Century Excellent Talents Support Program" by the Ministry of Education in 2009 and received the "Rao Yutai Basic Optics Award" in 2010. In 2013, he received the Tianjin Youth Science and Technology Award, and in 2014, he was selected as one of the 100 young discipline leaders training program of Nankai University.
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