A method and absorbing device for realizing high-efficiency absorption of circularly polarized light by graphene
A technology of circularly polarized light and graphene, which is applied in the field of realizing high-efficiency absorption of circularly polarized light by graphene, can solve the problems of low absorption efficiency, limitation, and difficulty in effectively estimating the position of resonance absorption peak, and achieve high absorption efficiency and enhanced absorption. The effect of efficiency
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Embodiment 1
[0037] Example 1: Realize the perfect absorption device for circularly polarized light by using graphene square plate
[0038] Such as figure 1 As shown, it is a schematic diagram of the cell of the periodic microstructure of the absorbing device. The period of the microstructure is P, and the background is air. The cell is composed of a graphene square sheet, a dielectric film layer and a metal mirror from top to bottom. ; Among them, the graphene square sheet is located in the center of the cell, and the side length is L; the dielectric film layer is used to separate the graphene and the metal reflector, and its thickness is d; the metal reflector is a piece of metal whose thickness is greater than the skin depth of the incident light wavelength Thin flakes (usually greater than 100nm), with the help of the high reflection effect of the metal mirror, are conducive to increasing the absorption efficiency of graphene to circularly polarized light. When circularly polarized li...
Embodiment 2
[0041] Embodiment 2: Utilize F-P (Fabry-Pérot) theory to estimate the method for the absorption peak position of graphene square sheet
[0042] At the resonant wavelength position, the graphene plasmon resonance formed under the excitation of electric fields in two orthogonal directions (x, y directions) of circularly polarized light will generate F-P resonance along the x and y directions, and the corresponding light absorption wavelength λ r The side length L of the graphene square sheet satisfies the formula (3):
[0043]
[0044] Among them, λ r is the resonant absorption wavelength of circularly polarized light, m is the number of resonant modes, L is the side length of the graphene square sheet, is the compensation phase; Re(n eff ) is the real part of the effective refractive index of the graphene plasmon, which can be obtained by solving the effective refractive index of the graphene plasmon mode in the "graphene-medium-metal" structure, and its size is related...
Embodiment 3
[0046] Embodiment 3: Based on graphene Fermi level E F A method to dynamically adjust the absorption peak
[0047] Changing the Fermi level E of graphene F , can change the absorption peak position of the graphene square sheet. Specifically, the wavelength of the absorption peak decreases with the increase of the Fermi energy level of graphene, resulting in a blue shift phenomenon. At the same time, the change in absorption rate is small, and high-efficiency absorption performance can be maintained. In applications, the Fermi level E of graphene can be changed by applying an external voltage F , and then the dynamic adjustment of the circularly polarized light absorption channel can be realized.
[0048] Based on Example 1, under the condition of keeping other parameters constant, change the Fermi energy level E of graphene F , calculate the absorption spectrum corresponding to the graphene square absorber, and get Figure 5 . From Figure 5 It can be seen that when th...
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