Chinese Optics Letters, Vol. 18, Issue 7, 070501 (2020)
A broadband polarization-independent two-port beam splitter under normal incidence based on encapsulated metal-dielectric reflective grating
Zhengkun Yin1,2, Yunkai Lu1,2, Junjie Yu1,*, and Changhe Zhou1,**
- 1Laboratory of Information Optics and Optoelectronic Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
- 2Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
An encapsulated metal-dielectric reflective grating is presented for broadband polarization-independent two-port beam splitting under normal incidence at the central wavelength of 800 nm. Different from traditional two-port grating splitters in the resonant region, this grating splitter is capable of separating light energy into ±1st orders with high efficiency in a broad waveband for both TE and TM polarizations. A unified method is proposed here for designing this grating splitter, which enables one to choose a grating structure quickly to realize an ultrabroad working waveband. The simulation results indicate that a bandwidth of 46.4 nm could be achieved for diffraction efficiency (defined as the ratio of the light energy diffracted only at the first order to the incident light energy) over 46% at the central wavelength of 800 nm. Moreover, the parameters of the grating structure can be flexibly adjusted with wavelengths using the unified method for various other applications, such as augmented reality, optical interconnections for computing, coherent beam combination, and complex vector beam shaping.
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