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Abstract
In this work, we proposed a state-of-the-art metasurface model that breaks the mirror symmetry and rotation symmetry of the structure. It consists of two-layer rotating gold split rings, and has the capability of chirality-selective absorption for circularly polarized light (CPL) in two bands. The absorption peaks for left- and right- circularly polarized (LCP&RCP) light appeared at 989 nm and 1404 nm, respectively, with the maximum absorptivity of 98.5% and 96.3%, respectively. By changing the rotation angle of the two-layer gold split rings, it could also be designed as a single-band chiral metasurface absorber, which only absorbed RCP light but not LCP light, and the absorptivity of RCP light could be up to 97.4%. Furthermore, we found our designed absorbers had the characteristics of great circular dichroism (CD) and symmetric absorption. The physical mechanism of the selective absorption of CPL by the absorbers may be explained by the current vector analysis. In addition, the absorption peak could be tuned with the changing of the geometrical parameters of the structure. The proposed chirality-selective metasurface absorbers could be used in CD spectral detection, optical communication, optical filtering, and other fields.
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1. Introduction
By means of dielectric and magnetic losses of materials and good impedance matching, electromagnetic absorbers could absorb the incident radiation and convert it into ohmic heat or other forms of energy [1,2]. In the optical band, due to the efficient use of light energy, optical absorbers play a crucial role in solar energy collection [3–6], photodetector [7–11], photoelectric sensor [12–14], and so on. The design of absorbers has experienced the development process from simple natural structures to complex artificial micro-/nano- structures. The classical absorber was based on one-dimensionally longitudinal stack and adopted the metal-insulator-metal (MIM) model [15–17]. The dielectric medium was sandwiched between the top and bottom metal layers to form an optical cavity with a finite length, which causes the incident wave to generate resonance to be absorbed. Such absorbers were simple in design and easy to be manufactured, but had the disadvantages of large size and narrow absorption band. Later, three-dimensional structures such as grating [18–20], holes array [21,22], spherical voids [23], convex grooves [24], and heterointerface engineering [25], were gradually used for the design of absorbers. These structures could further reduce the impedance difference between air and absorber, improve the absorptivity and expand the absorption bandwidth. However, in practical applications, the impedance matching by these relatively simple structures still require improvement to meet the demands of higher accuracy. In recent years, artificial metamaterials have emerged as a promising solution. Metamaterials could adjust the permittivity and permeability simultaneously, and the locally design of the nanostructures could achieve perfect absorption at specific frequencies through impedance matching with free space, effectively improving the efficiency and accuracy of the absorber. Metasurface absorbers were composed of a variety of planar unit structures, such as square [26,27], grating [28], cross [29,30], round [31,32], nanoparticle [33,34], open ring resonator [35,36], etc. These metasurface structures further improve the absorptivity and broaden the bandwidth of the absorber by planar extension or vertical stack of the unit cells. Based on these characteristics, metasurface absorber could also obtain the advantages of high absorbance, large incidence angle, polarization insensitive, tunable function, etc., and had a great application prospect.
Metasurface absorbers in most applications, such as photovoltaic power generation and electromagnetic shielding, need to be polarization-insensitive to ensure high absorptivity in different working environments. However, in special applications, such as optical communication using circularly polarized beams [37–40], photoelectric detection through circular dichroism (CD) effect [41–43], and biochemical detection based on CD spectral measurements [44–46], absorbers were sensitive to the polarization of light, especially circularly polarized light (CPL). Metasurface absorber based on the chiral structure was currently recognized as the optimal choice for CPL-sensitive to obtain different responses [47,48]. The response to CPL by the chiral structure was closely related to their symmetry [49]. Metasurface absorbers designed with chiral structures could be classified into four types based on their symmetry-breaking routes: absorbers that broke mirror symmetry [50–54], absorbers that additionally broke rotational symmetry [55–57], and both types could be designed in single- [58–63], or multi-layer configurations [64,65]. All absorbers have been proven to absorb a single type of CPL, but not all have been proven to achieve the selective absorption of two types of CPL. Furthermore, in some fields, such as CD spectral molecular detection [46,66], to identify the spectral characteristics of target molecules in more detail and improve the detection accuracy, it is even required to detect two types of CPL simultaneously.
In this paper, we proposed a metasurface structure with two-layer rotating gold split rings. This structure was chiral, broke both mirror and rotational symmetry, and could be used for asymmetric selective absorption of two types of CPL in dual bands. Due to the chirality of the structure, it could also achieve the function of single-band absorption. Firstly, the absorptivity and band of CPL were calculated theoretically with the transfer matrix method by using the multiple transmission and reflection interference model, and further compared with those by simulation. Then, we studied the effect of the relative rotation angle of different two-layer gold split rings on the selective absorption of the absorbers. Next, the current analysis was used to illustrate the physical mechanism of selective absorption. In addition, we tested the influence of different structural parameters and working angles on the absorption effect, and analyzed the tolerance to processing errors and the robustness of the structure parameters changing of the absorbers. Our proposed dual-band chirality-selective metasurface absorber has potential applications in photoelectric detection, biochemical detection, chiral imaging, circular polarization communication, and other fields.
2. Method and theory
2.1. Metasurface design
The structure of our proposed metasurface absorber is shown in Fig. 1(a). When the CPL was incident on the absorber from above, the response of the absorber to the two types of CPL was different due to the chirality of the split rings, which leads to the chirality-selective absorption effect for the CPL. Figures 1(b) and (c) were detailed views of the metasurface unit. Each unit consisted of two gold split rings and a SiO2-gold substrate. The dispersion function of gold is from the CRC Handbook of Chemistry & Physics. The permittivity of SiO2 is about 2.09, from the Handbook of Optical Constants of Solids I - III. They can be selected in the simulation software. The metasurface unit was numerically simulated using the finite-difference time-domain (Lumerical, FDTD solutions). The periodic boundary conditions were set in the x and y directions, and the perfect matching layer (PML) condition was set in the z direction. Due to the presence of the gold layer, incoming CPL could not penetrate the structure and produce transmitted light, but would only be absorbed and reflected. Therefore, the absorptivity for LCP and RCP light by the metasurface structure could be analyzed based on the intensity of the reflected light. We set up a monitor to obtain the intensity, and then the absorptivity of the structure was calculated at different wavelengths.
Fig. 1. (a) Schematic of the metasurface absorber. (b) The metasurface unit. The unit period P = 380 nm, the height of the SiO2 medium h1 = 170 nm, and the height of the gold substrate h2 = 100 nm. Two-layer gold split rings are distributed on the upper surface and inside the medium. The outer radius R = 130 nm, the inner radius r = 40 nm, the split angle of the ring is 90°, and the rotation angle α = 270°. The lower ring has a relative angle β = 75° with respect to the upper ring. (c) The single metasurface unit structure in the x-z view. The two rings have the same thickness t = 25 nm, and are separated by a distance d = 125 nm.
2.2 Multiple transmission and reflection interference model
The transmission and reflection of the incident light mainly occur in the multilayer structure of the absorber. The transfer matrix method based on the multiple transmission and reflection interference model could be used to calculate the theoretical transmission and reflection intensities among the multilayers [67–70]. The model in Fig. 2(a) could represent our proposed absorber’s structure. Since the thickness of the gold split rings was very thin compared to the working wavelength λ and the distance d between the two rings, and the gold layer was only used to isolate the transmission light, they could be considered as three ideal metal layers with no thickness dividing the structure into four parts. The incident light in the air was transmitted and reflected multiple times in the two Fabry-Pérot like cavities structure.
Fig. 2. (a) Diagram of a simplified multiple transmission reflection interferences model. (b) The simplified input-output system model of metasurface absorber.
The transfer matrix between each metal layer could be expressed as [67]:
CPL is incident only in “a” and its electrical field is represented as $E_a^B$. The gold layer is set in “d”, so there is only a very weak transmitted field, and $E_d^B = E_d^F = 0$. $E_a^F$ is the reflection field in “a”. So far, the transmittance and reflectivity for the incident CPL can be calculated step by step. Therefore, the absorption for CPL can be obtained by the following formula:
3. Results and discussions
3.1 Chirality-selective absorption
The absorptivity of the absorber was simulated by the FDTD method, and Fig. 3 shows the theoretical calculation and numerical simulation results of the absorption for CPL by the metasurface absorbers at different working bands. Figure 3(a) shows the absorption results of the dual-band chirality-selective absorber, and Fig. 3(b) shows the absorption results of the single-band chiral absorber. According to the numerical simulation results in Fig. 3(a), the selective absorptivity for LCP light is up to the maximal value of 98.5% at λ1 = 989 nm, while the selective absorption for RCP light up to 96.3% at λ2 = 1404 nm. The results show that the absorber selectively absorbs one type of CPL nearly perfectly in a specific band, while the absorptivity of the other type of CPL remained below 10%. Due to the chiral structure of the two-layer gold split rings, it can be predicted that the structure could also be designed as a non-selective single-band chiral absorber. Figure 3(b) shows the simulation absorption results of the absorber in the condition of α = 210°. At λ3 = 926 nm, the absorptivity for RCP light is up to the maximal value of 97.4%, while that of LCP light remains below 10%. The absorber can only absorb one type of CPL without selective absorption capability. By adjusting the rotation angle α of the two-layer gold split rings, it is possible not only to achieve the single-band CPL absorption function by the classical chiral absorber, but also to realize the dual-band selective absorber, which meets the requirements of different aspects in practical applications.
Fig. 3. Theoretical calculation and numerical simulation results of the absorption for CPL and the unit cells of the metasurface absorbers. (a) is the dual-band chirality-selective absorber (α = 270°) and (b) is the single-band chiral absorber (α = 210°).
Next, the absorptivity was calculated with transfer matrix method using the multiple interference model. Since the bottom gold split ring and the gold layer are close, the fields inside them will be coupled, they were regarded as a module in the calculation. As can be seen from Fig. 3 showing the comparison between theoretical calculation and numerical simulation results, although there is a slight difference in the maximum absorptivity, the absorption bands were the same. The consistency between the theoretical and simulation results demonstrates our absorbers’ nearly perfect performance for selective absorption. These differences are considered mainly from two factors. On the one hand, the thickness of the ring was ignored in the theoretical calculation, while not in the simulation. On the other hand, the medium outside the absorber will affect the theoretical calculation for absorptivity. Nevertheless, these differences are within an acceptable range.
3.2 Asymmetric selective absorption
The selective absorption capability of the absorber comes from the symmetry of the structure being broken, so the absorptivity after that was broken from different directions was observed. Figures 4(a) and (c) show the absorption results of two dual-band chirality-selective absorbers for CPL. In Fig. 4(a) (β = 75°), the absorber strongly absorbs LCP light at λ1 = 989 nm and RCP light at λ2 = 1404 nm. The absorption effect is reversed in Fig. 4(c) (β = 285°). The two dual-band absorbers absorb different types of CPL at the same wavelength. It is predicted that the single-band chiral absorber has this reciprocal absorption function. In Fig. 4(b) (β = 75°), there is a strong absorption for RCP light near λ3 = 926 nm. In Fig. 4(d) (β = 285°), it has a strong absorption for LCP light near λ3. Both types of absorbers exhibit asymmetric selective absorption characteristics. By modifying the structural parameters of the absorbers, the selective absorption effect will appear to have an opposite performance at the same working band. We found by changing β to 285°, the circular angle of the original β = 75°, there is reciprocity in the absorption for CPL.
Fig. 4. The absorption curves and the unit cells of the dual-band chirality-selective metasurface absorber, with (a) β = 75° and (c) β = 285°. The absorption curves and the unit cells of the single-band chiral metasurface absorber, with (b) β = 75° and (d) β = 285°.
We further studied the absorption effect of the absorbers at different β, and used the CD effect curves to represent the selective absorption capability of the absorbers. The CD effect curve represents the difference between the absorption for two types of CPL by the absorber at a specific wavelength, which is defined as: $\textrm{CD} = {A_{LCP}} - {A_{RCP}}$. If the CD is positive, it means that at this wavelength, the absorber mainly absorbs LCP light and few RCP light. If CD is negative, the absorption effect is the opposite. In this paper, the CD curves of the two absorbers at different β were obtained through numerical simulation, as shown in Fig. 5. Here, we take the dual-band chirality-selective absorber as an example. In Fig. 5(a), at the λ1, when β starts to increase from 0° to 75°, the CD will gradually increase from 0, and when β increases to 120°, the CD will reverse to a negative value, and will gradually decrease and become 0 again. When β increases again from 180°, CD gradually increases again from 0 at the λ1, and when β increases to 285°, CD again reverses into a negative value, and gradually decreases to 0 as β continues to increase to 360° (0°). At the specific working band, when β = 75°, both absorbers have |CD| > 0.9, which proves that the absorbers have a huge CD effect. In addition, if two absorbers whose β added up to 2π, their CD curves are the opposite and show an opposite CD effect, i.e., the absorption for different CPL at the same working band. It predicted that the reciprocity of absorption effects of a pair of absorbers is associated with the mutual symmetry of their structures.
Fig. 5. Schematic diagram of the CD curves measured after changing β. (a) is the dual-band chirality-selective absorber, (b) is the single-band chiral absorber. For curves of the same color, the β values of the solid and dotted lines added up to π or 2π. (c - f) Top views of metasurface units. Their β is set to 75°, 285°, 0°, and 180°, respectively. In the top view, the two-layer gold rings overlap visually, and the lower ring is marked by black dotted line. The red dotted lines represent the axis of symmetry.
We next explored the origin of this reciprocal absorption from the geometric structure of the metasurface absorber, so we selected several absorbers under different β and the top view of their one unit was shown in Fig. 5. In Figs. 5(c) and (d), β is set to 75° and 285°, respectively. While the two structures themselves did not mirror-symmetric with the red dashed line as the axis of symmetry, they were mirror images of each other. We inferred that the reciprocal absorption capability comes from symmetry. In Fig. 5(e) with β = 0°, and 5(f) with β = 180°, the two structures themselves are mirrored symmetrically by the red dashed line. As shown in Fig. 5(a), the CD effect of these two structures was 0, and there was no CD effect. Therefore, we propose a hypothesis that breaking the mirror symmetry of the structure is associated with obtaining the CD.
3.3 Structural parameters test
Considering that errors may occur in the actual fabrication of the metasurface, we tested the effect of changing the geometric parameters of the metasurface structure on absorptivity. The geometric parameters of the reference group were as follows: the inner radius r = 40 nm, the outer radius R = 130 nm, the thickness t = 25 nm, and the distance d = 125 nm. The absorption results of the dual-band selective absorbers with different parameters are shown in Fig. 6. In Fig. 6(a), as r decreases, the absorption peak blue-shift, and the absorptivity of LCP light slightly enhanced, while that of RCP light significantly weakened. As r increases, the absorption peak red-shift, and the absorptivity for the LCP and RCP light decreases. Similarly, in Fig. 6(b), the absorption peak blue-shift as R decreases, and the absorption peak red-shift as R increases. In both cases, the absorption of CPL is reduced. As shown in Figs. 6(a) and (b), the changing of the absorber's r and R greatly affects the final absorption band, providing a range of operating bands. In Fig. 6(c), when the change of d is slight, the maximum absorptivity of the absorber, the full width at half maximum (FWHM), and the positions of the absorption peak all change slightly. The quality factors of the absorption peaks at the resonance wavelengths are low, which is the result of the combination of Fabry-Pérot resonance and localized surface plasmon resonance. In Fig. 6(d), the change of t does not affect the band of the absorption peak but slightly reduce the absorptivity. As shown in Figs. 6(c) and (d), as the t and d changed, the final absorptivity and absorption band show little change. Hence, in the practical production of the absorber, there is a certain tolerance in processing t and d. Even if a processing error occurs, the change of the absorption peaks is still within the allowable range to ensure that the quality of the absorber meets the requirements.
Fig. 6. (a)-(d) The absorptivity curves of dual-band selective absorbers with different geometric parameters under CPL incidence. The solid and dashed lines represent LCP and RCP light incidence, respectively.
3.4 Incidence angle test
Lastly, considering the conditions of incidences with angles in practical applications, we tested the absorption performance of the dual-band absorber at different incident angles. In Fig. 7, as the incidence angle i increases from 0°, the maximum absorptivity of the absorber for LCP and RCP light decreases, and the absorption bands shift slightly. The FWHM of LCP light does not change obviously, and the FWHM of RCP light increases. Although the maximum absorptivity of the absorber is greatly reduced and the absorption peaks shift when the CPL is oblique incidence, two absorption bands are still maintained. The selective absorption of the absorber is a result of the combinations of both Fabry-Pérot resonance and localized surface plasmon resonance. Due to the angle sensitivity of Fabry-Pérot resonance, when i ≠ 0, the influence of Fabry-Pérot resonance increases, and the absorption results change greatly.
Fig. 7. The absorptivity curves of dual-band selective absorbers at the incidence of CPL at different incidence angles. The solid and dashed lines represent LCP and RCP light incidence, respectively.
4. Conclusions
In summary, we proposed a chirality-selective metasurface absorber composed of two layers of gold split rings and a SiO2-gold substrate. The two-layer metasurface structure broke both mirror symmetry and rotational symmetry. We proved that the single/multi-layer chiral metasurface absorber with/without additional rotational symmetry breaking could achieve selective CPL absorption. The proposed dual-band chirality-selective metasurface absorber could absorb LCP and RCP light at 989 nm and 1404 nm with 98.5% and 96.3% absorptivity, respectively. The proposed single-band metasurface absorber could only absorb RCP light at 926 nm, and the absorptivity reached 97.4%. Our absorber could achieve a nearly perfect chirality-selective absorption effect in specific working bands, which was confirmed by the consistency between theoretical and simulation results. We also proposed a hypothesis that the reciprocal absorption effect of the absorber was associated with the mirror symmetry of the unit structure. This hypothesis will be useful in the domain of chiral structures. By means of current vector analysis, it was theoretically explained that our proposed metasurface absorber has a huge CD effect. The proposed metasurface absorbers were also tunable, suitable for various working conditions. The proposed chirality-selective absorbers can provide unique advantages in many applications, such as expanding the communication frequency band in optical communication using CPL, increasing the detection sensitivity in photoelectric detection through CD effects, and improving the detection accuracy of target molecules in biochemical detection based on CD spectral measurement.
Funding
National Natural Science Foundation of China (61805119, 62275122); Natural Science Foundation of Jiangsu Province (BK20180468, BK20180469); Fundamental Research Funds for the Central Universities (30919011275).
Disclosures
The authors declare no conflicts of interest.
Data availability
Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.
Supplemental document
See Supplement 1 for supporting content.
References
1. Y. X. Cui, Y. R. He, Y. Jin, F. Ding, L. Yang, Y. Q. Ye, S. M. Zhong, Y. Y. Lin, and S. L. He, “Plasmonic and metamaterial structures as electromagnetic absorbers,” Laser Photonics Rev. 8(4), 495–520 (2014). [CrossRef]
2. M. Qin, L. Zhang, and H. Wu, “Dielectric loss mechanism in electromagnetic wave absorbing materials,” Adv. Sci. 9(10), e2105553 (2022). [CrossRef]
3. N. P. Sergeant, O. Pincon, M. Agrawal, and P. Peumans, “Design of wide-angle solar-selective absorbers using aperiodic metal-dielectric stacks,” Opt. Express 17(25), 22800–22812 (2009). [CrossRef]
4. S. Molesky, C. J. Dewalt, and Z. Jacob, “High temperature epsilon-near-zero and epsilon-near-pole metamaterial emitters for thermophotovoltaics,” Opt. Express 21(S1), A96–A110 (2013). [CrossRef]
5. E. Rephaeli and S. H. Fan, “Absorber and emitter for solar thermophotovoltaic systems to achieve efficiency exceeding the shockley-queisser limit,” Opt. Express 17(17), 15145–15159 (2009). [CrossRef]
6. N. P. Sergeant, M. Agrawal, and P. Peumans, “High performance solar-selective absorbers using coated sub-wavelength gratings,” Opt. Express 18(6), 5525–5540 (2010). [CrossRef]
7. M. W. Knight, H. Sobhani, P. Nordlander, and N. J. Halas, “Photodetection with active optical antennas,” Science 332(6030), 702–704 (2011). [CrossRef]
8. A. Sobhani, M. W. Knight, Y. M. Wang, B. Zheng, N. S. King, L. V. Brown, Z. Y. Fang, P. Nordlander, and N. J. Halas, “Narrowband photodetection in the near-infrared with a plasmon-induced hot electron device,” Nat. Commun. 4(1), 1643 (2013). [CrossRef]
9. W. Li and J. Valentine, “Metamaterial perfect absorber based hot electron photodetection,” Nano Lett. 14(6), 3510–3514 (2014). [CrossRef]
10. B. Y. Zheng, Y. Wang, P. Nordlander, and N. J. Halas, “Color-selective and cmos-compatible photodetection based on aluminum plasmonics,” Adv. Mater. 26(36), 6318–6323 (2014). [CrossRef]
11. J. Ho, Z. Dong, H. S. Leong, J. Zhang, F. Tjiptoharsono, S. Daqiqeh Rezaei, K. C. H. Goh, M. Wu, S. Li, J. Chee, C. P. Y. Wong, A. I. Kuznetsov, and J. K. W. Yang, “Miniaturizing color-sensitive photodetectors via hybrid nanoantennas toward submicrometer dimensions,” Sci. Adv. 8(47), eadd3868 (2022). [CrossRef]
12. N. Liu, M. Mesch, T. Weiss, M. Hentschel, and H. Giessen, “Infrared perfect absorber and its application as plasmonic sensor,” Nano Lett. 10(7), 2342–2348 (2010). [CrossRef]
13. D. Hasan and C. Lee, “Hybrid metamaterial absorber platform for sensing of co2 gas at mid-ir,” Adv. Sci. 5(5), 1700581 (2018). [CrossRef]
14. K. Bhattarai, Z. H. Ku, S. Silva, J. Jeon, J. O. Kim, S. J. Lee, A. Urbas, and J. F. Zhou, “A large-area, mushroom-capped plasmonic perfect absorber: Refractive index sensing and fabry-perot cavity mechanism,” Adv. Opt. Mater. 3(12), 1779–1786 (2015). [CrossRef]
15. G. Kajtar, M. Kafesaki, E. N. Economou, and C. M. Soukoulis, “Theoretical model of homogeneous metal-insulator-metal perfect multi-band absorbers for the visible spectrum,” J. Phys. D: Appl. Phys. 49(5), 055104 (2016). [CrossRef]
16. M. Yan, “Metal-insulator-metal light absorber: A continuous structure,” J. Opt. 15(2), 025006 (2013). [CrossRef]
17. B. J. Lee and Z. M. Zhang, “Design and fabrication of planar multilayer structures with coherent thermal emission characteristics,” J. Appl. Phys. 100(6), 063529 (2006). [CrossRef]
18. H. T. Miyazaki, K. Ikeda, T. Kasaya, K. Yamamoto, Y. Inoue, K. Fujimura, T. Kanakugi, M. Okada, K. Hatade, and S. Kitagawa, “Thermal emission of two-color polarized infrared waves from integrated plasmon cavities,” Appl. Phys. Lett. 92(14), 141114 (2008). [CrossRef]
19. K. Ikeda, H. T. Miyazaki, T. Kasaya, K. Yamamoto, Y. Inoue, K. Fujimura, T. Kanakugi, M. Okada, K. Hatade, and S. Kitagawa, “Controlled thermal emission of polarized infrared waves from arrayed plasmon nanocavities,” Appl. Phys. Lett. 92(2), 021117 (2008). [CrossRef]
20. S. Ogawa and M. Kimata, “Direct fabrication and characterization of high-aspect-ratio plasmonic nanogratings using tapered-sidewall molds,” Opt. Mater. Express 7(2), 633–640 (2017). [CrossRef]
21. J. Braun, B. Gompf, G. Kobiela, and M. Dressel, “How holes can obscure the view: Suppressed transmission through an ultrathin metal film by a subwavelength hole array,” Phys. Rev. Lett. 103(20), 203901 (2009). [CrossRef]
22. C. Hu, L. Liu, Z. Zhao, X. Chen, and X. Luo, “Mixed plasmons coupling for expanding the bandwidth of near-perfect absorption at visible frequencies,” Opt. Express 17(19), 16745–16749 (2009). [CrossRef]
23. M. Wang, C. Hu, M. Pu, C. Huang, Z. Zhao, Q. Feng, and X. Luo, “Truncated spherical voids for nearly omnidirectional optical absorption,” Opt. Express 19(21), 20642–20649 (2011). [CrossRef]
24. T. Sondergaard, S. M. Novikov, T. Holmgaard, R. L. Eriksen, J. Beermann, Z. Han, K. Pedersen, and S. I. Bozhevolnyi, “Plasmonic black gold by adiabatic nanofocusing and absorption of light in ultra-sharp convex grooves,” Nat. Commun. 3(1), 969 (2012). [CrossRef]
25. L. Liang, W. Gu, Y. Wu, B. Zhang, G. Wang, Y. Yang, and G. Ji, “Heterointerface engineering in electromagnetic absorbers: New insights and opportunities,” Adv. Mater. 34(4), e2106195 (2022). [CrossRef]
26. T. Maier and H. Brueckl, “Multispectral microbolometers for the midinfrared,” Opt. Lett. 35(22), 3766–3768 (2010). [CrossRef]
27. J. M. Hao, J. Wang, X. L. Liu, W. J. Padilla, L. Zhou, and M. Qiu, “High performance optical absorber based on a plasmonic metamaterial,” Appl. Phys. Lett. 96(25), 251104 (2010). [CrossRef]
28. Z. J. Zhang, Z. Y. Yu, Y. Z. Liang, and T. Xu, “Dual-band nearly perfect absorber at visible frequencies,” Opt. Mater. Express 8(2), 463–468 (2018). [CrossRef]
29. K. Chen, R. Adato, and H. Altug, “Dual-band perfect absorber for multispectral plasmon-enhanced infrared spectroscopy,” ACS Nano 6(9), 7998–8006 (2012). [CrossRef]
30. N. Chen, P. Pitchappa, C. P. Ho, D. Hasan, P. Kropelnicki, M. Alioto, and C. Lee, “Polarization controllable multispectral symmetry-breaking absorber in mid-infrared,” J. Appl. Phys. 120(6), 063105 (2016). [CrossRef]
31. C. W. Cheng, M. N. Abbas, C. W. Chiu, K. T. Lai, M. H. Shih, and Y. C. Chang, “Wide-angle polarization independent infrared broadband absorbers based on metallic multi-sized disk arrays,” Opt. Express 20(9), 10376 (2012). [CrossRef]
32. J. Kim, K. Han, and J. W. Hahn, “Selective dual-band metamaterial perfect absorber for infrared stealth technology,” Sci. Rep. 7(1), 6740 (2017). [CrossRef]
33. S. A. Dereshgi and A. K. Okyay, “Large area compatible broadband superabsorber surfaces in the vis-nir spectrum utilizing metal-insulator-metal stack and plasmonic nanoparticles,” Opt. Express 24(16), 17644–17653 (2016). [CrossRef]
34. A. Monti, A. Alu, A. Toscano, and F. Bilotti, “Narrowband transparent absorbers based on ellipsoidal nanoparticles,” Appl. Opt. 56(27), 7533–7538 (2017). [CrossRef]
35. K. B. Alici, A. B. Turhan, C. M. Soukoulis, and E. Ozbay, “Optically thin composite resonant absorber at the near-infrared band: A polarization independent and spectrally broadband configuration,” Opt. Express 19(15), 14260–14267 (2011). [CrossRef]
36. A. Nagarajan, K. Vivek, M. Shah, V. G. Achanta, and G. Gerini, “A broadband plasmonic metasurface superabsorber at optical frequencies: Analytical design framework and demonstration,” Adv. Opt. Mater. 6(16), 1800253 (2018). [CrossRef]
37. E. K. Kaivanto, M. Berg, E. Salonen, and P. de Maagt, “Wearable circularly polarized antenna for personal satellite communication and navigation,” IEEE Trans. Antennas Propag. 59(12), 4490–4496 (2011). [CrossRef]
38. I. Nadeem, M. Alibakhshikenari, F. Babaeian, A. A. Althuwayb, B. S. Virdee, L. Azpilicueta, S. Khan, I. Huynen, F. Falcone, T. A. Denidni, and E. Limiti, “A comprehensive survey on ‘circular polarized antennas’ for existing and emerging wireless communication technologies,” J. Phys. D: Appl. Phys. 55(3), 033002 (2022). [CrossRef]
39. H. Aissat, L. Cirio, M. Grzeskowiak, J. M. Laheurte, and O. Picon, “Reconfigurable circularly polarized antenna for short-range communication systems,” IEEE Trans. Microwave Theory Tech. 54(6), 2856–2863 (2006). [CrossRef]
40. R. Farshchi, M. Ramsteiner, J. Herfort, A. Tahraoui, and H. T. Grahn, “Optical communication of spin information between light emitting diodes,” Appl. Phys. Lett. 98(16), 162508 (2011). [CrossRef]
41. M. Schulz, F. Balzer, D. Scheunemann, O. Arteaga, A. Lutzen, S. C. J. Meskers, and M. Schiek, “Chiral excitonic organic photodiodes for direct detection of circular polarized light,” Adv. Funct. Mater. 29(16), 1900684 (2019). [CrossRef]
42. Y. Phal, K. Yeh, and R. Bhargava, “Concurrent vibrational circular dichroism measurements with infrared spectroscopic imaging,” Anal. Chem. 93(3), 1294–1303 (2021). [CrossRef]
43. N. J. Greenfield, “Using circular dichroism spectra to estimate protein secondary structure,” Nat. Protoc. 1(6), 2876–2890 (2006). [CrossRef]
44. S. Feng, R. Chen, J. Lin, J. Pan, Y. Wu, Y. Li, J. Chen, and H. Zeng, “Gastric cancer detection based on blood plasma surface-enhanced raman spectroscopy excited by polarized laser light,” Biosens. Bioelectron. 26(7), 3167–3174 (2011). [CrossRef]
45. B. Kunnen, C. Macdonald, A. Doronin, S. Jacques, M. Eccles, and I. Meglinski, “Application of circularly polarized light for non-invasive diagnosis of cancerous tissues and turbid tissue-like scattering media,” J. Biophotonics 8(4), 317–323 (2015). [CrossRef]
46. R. Gao, L. Xu, C. Hao, C. Xu, and H. Kuang, “Circular polarized light activated chiral satellite nanoprobes for the imaging and analysis of multiple metal ions in living cells,” Angew. Chem., Int. Ed. Engl. 58(12), 3913–3917 (2019). [CrossRef]
47. J. Q. Cheng, Z. C. Li, D. Y. Choi, S. W. Yu, W. W. Liu, H. Y. Wang, Y. B. Zhang, H. Cheng, J. G. Tian, and S. Q. Chen, “Spin-selective full and subtle light intensity manipulation with diatomic metasurfaces,” Adv. Opt. Mater., (2022).
48. Z. Li, W. Liu, H. Cheng, D. Y. Choi, S. Chen, and J. Tian, “Spin-selective full-dimensional manipulation of optical waves with chiral mirror,” Adv. Mater. 32(26), e1907983 (2020). [CrossRef]
49. C. Menzel, C. Rockstuhl, and F. Lederer, “Advanced jones calculus for the classification of periodic metamaterials,” Phys. Rev. A 82(5), 053811 (2010). [CrossRef]
50. L. Ouyang, W. Wang, D. Rosenmann, D. A. Czaplewski, J. Gao, and X. Yang, “Near-infrared chiral plasmonic metasurface absorbers,” Opt. Express 26(24), 31484–31489 (2018). [CrossRef]
51. S. T. Yin, D. Xiao, J. X. Liu, K. Li, H. He, S. Z. Jiang, D. Luo, X. W. Sun, W. Ji, and Y. J. Liu, “Reconfigurable chiral metasurface absorbers based on liquid crystals,” IEEE Photonics J. 10(6), 1–9 (2018). [CrossRef]
52. E. Plum, “Extrinsic chirality: Tunable optically active reflectors and perfect absorbers,” Appl. Phys. Lett. 108(24), 241905 (2016). [CrossRef]
53. C. Wang, J. Liang, Y. Xiao, T. Cai, H. Hou, and H. Li, “High-performance and broadband chirality-dependent absorber based on planar spiral metasurface,” Opt. Express 27(10), 14942–14950 (2019). [CrossRef]
54. M. Pan, Q. Li, Y. Hong, L. Cai, J. Lu, and M. Qiu, “Circular-polarization-sensitive absorption in refractory metamaterials composed of molybdenum zigzag arrays,” Opt. Express 26(14), 17772–17780 (2018). [CrossRef]
55. J. Li, C. Zheng, J. Li, H. Zhao, X. Hao, H. Xu, Z. Yue, Y. Zhang, and J. Yao, “Polarization-dependent and tunable absorption of terahertz waves based on anisotropic metasurfaces,” Opt. Express 29(3), 3284–3295 (2021). [CrossRef]
56. Y. Cheng, Y. F. Li, H. Wang, J. F. Wang, Z. Qin, and S. B. Qu, “Circular dichroism assisted bi-directional absorbers,” J. Phys. D: Appl. Phys. 55(9), 095101 (2022). [CrossRef]
57. Y. Ren, T. Zhou, C. Jiang, and B. Tang, “Thermally switching between perfect absorber and asymmetric transmission in vanadium dioxide-assisted metamaterials,” Opt. Express 29(5), 7666–7679 (2021). [CrossRef]
58. M. S. Mahmud, D. Rosenmann, D. A. Czaplewski, J. Gao, and X. Yang, “Chiral plasmonic metasurface absorbers in the mid-infrared wavelength range,” Opt. Lett. 45(19), 5372–5375 (2020). [CrossRef]
59. Z. Zhang, X. Zhang, Y. Xu, X. Chen, X. Feng, M. Liu, Q. Xu, M. Kang, J. Han, and W. Zhang, “Coherent chiral-selective absorption and wavefront manipulation in single-layer metasurfaces,” Adv. Opt. Mater. 9(3), 2001620 (2021). [CrossRef]
60. D. Xiao, Y. J. Liu, S. Yin, J. Liu, W. Ji, B. Wang, D. Luo, G. Li, and X. W. Sun, “Liquid-crystal-loaded chiral metasurfaces for reconfigurable multiband spin-selective light absorption,” Opt. Express 26(19), 25305–25314 (2018). [CrossRef]
61. B. Tang, Z. Y. Li, E. Palacios, Z. H. Liu, S. Butun, and K. Aydin, “Chiral-selective plasmonic metasurface absorbers operating at visible frequencies,” IEEE Photonics Technol. Lett. 29(3), 295–298 (2017). [CrossRef]
62. W. Gao, C. Huang, Z. Feng, M. Li, and J. Dong, “Circular dichroism metamirror with diversified chiral molecules combinations,” Opt. Express 29(21), 33367–33379 (2021). [CrossRef]
63. H. Tang, D. Rosenmann, D. A. Czaplewski, X. Yang, and J. Gao, “Dual-band selective circular dichroism in mid-infrared chiral metasurfaces,” Opt. Express 30(11), 20063–20075 (2022). [CrossRef]
64. Y. Z. Cheng, H. R. Chen, J. C. Zhao, X. S. Mao, and Z. Z. Cheng, “Chiral metamaterial absorber with high selectivity for terahertz circular polarization waves,” Opt. Mater. Express 8(5), 1399–1409 (2018). [CrossRef]
65. Y. Cheng, F. Chen, and H. Luo, “Plasmonic chiral metasurface absorber based on bilayer fourfold twisted semicircle nanostructure at optical frequency,” Nanoscale Res. Lett. 16(1), 12 (2021). [CrossRef]
66. Y. Zhao, A. N. Askarpour, L. Y. Sun, J. W. Shi, X. Q. Li, and A. Alu, “Chirality detection of enantiomers using twisted optical metamaterials,” Nat. Commun. 8(1), 14180 (2017). [CrossRef]
67. Z. Shen and Q. He, “Mutual circular polarization conversions in asymmetric transmission and reflection modes by three-layer metasurface with gold split-rings,” Opt. Express 29(21), 34850–34862 (2021). [CrossRef]
68. S. E. Mun, J. Hong, J. G. Yun, and B. Lee, “Broadband circular polarizer for randomly polarized light in few-layer metasurface,” Sci. Rep. 9(1), 2543 (2019). [CrossRef]
69. J. Y. Liu, Z. C. Li, W. W. Liu, H. Cheng, S. Q. Chen, and J. G. Tian, “High-efficiency mutual dual-band asymmetric transmission of circularly polarized waves with few-layer anisotropic metasurfaces,” Adv. Opt. Mater. 4(12), 2028–2034 (2016). [CrossRef]
70. N. K. Grady, J. E. Heyes, D. R. Chowdhury, Y. Zeng, M. T. Reiten, A. K. Azad, A. J. Taylor, D. A. Dalvit, and H. T. Chen, “Terahertz metamaterials for linear polarization conversion and anomalous refraction,” Science 340(6138), 1304–1307 (2013). [CrossRef]
