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Niu Jinke, Liang Binming, Zhuang Songlin, et al. Dual subwavelength imaging based on two-dimensional photonic crystals[J]. Opto-Electronic Engineering, 2019, 46(8): 180577. doi: 10.12086/oee.2019.180577
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Dual subwavelength imaging based on two-dimensional photonic crystals
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Abstract
A focusing structure which can achieve negative refraction and dual subwavelength imaging is proposed, which is based on two-dimensional (2D) photonic crystal (PC) which consisting of air holes in silicon. The light radiated from a point source can form two images through a triangular PC. The transmittance of light is increased and the side spot at image2 is eliminated by adding the gratings on the sides of the PC. When the air slit of gratings is w=0.76a and the distance between gratings and PC is dg=0.1a, the minimum half-width of the image1 reaches 0.433λ, the maximum half-width of image2 reaches 0.842λ, which are both lower than incident wavelength. In addition, the PC realizes wide-spectrum dual subwavelength imaging when the incident wavelength varies from 3.19a to 3.26a. The position formulas between images and point source are also demonstrated. Based on the results, we propose a new confocal system based on PC that can achieve subwavelength imaging.-
Keywords:
- photonic crystals /
- negative refraction /
- dual imaging /
- subwavelength imaging /
- confocal
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References
[1] Veselago V G. The electrodynamics of substances with simultaneously negative values of ε and μ[J]. Soviet Physics Uspekhi, 1968, 10(4): 509. doi: 10.1070/PU1968v010n04ABEH003699 [2] Pendry J B. Negative refraction makes a perfect lens[J]. Physical Review Letters, 2000, 85(18): 3966-3969. doi: 10.1103/PhysRevLett.85.3966 [3] Kang M, Chen J, Li S M, et al. Optical spin-dependent angular shift in structured metamaterials[J]. Optics Letters, 2011, 36(19): 3942-3944. doi: 10.1364/OL.36.003942 [4] Iyer A K, Eleftheriades G V. Mechanisms of subdiffraction free-space imaging using a transmission-line metamaterial superlens: an experimental verification[J]. Applied Physics Letters, 2008, 92(13): 131105. doi: 10.1063/1.2904635 [5] Shelby R A, Smith D R, Schultz S. Experimental verification of a negative index of refraction[J]. Science, 2001, 292(5514): 77-79. doi: 10.1126/science.1058847 [6] Martı́n F, Bonache J, Falcone F, et al. Split ring resonator-based left-handed coplanar waveguide[J]. Applied Physics Letters, 2003, 83(22): 4652-4654. doi: 10.1063/1.1631392 [7] Joannopoulos J D, Villeneuve P R, Fan S H. Photonic crystals: putting a new twist on light[J]. Nature, 1997, 386(6621): 143-149. doi: 10.1038/386143a0 [8] Mekis A, Chen J C, Kurland I, et al. High transmission through sharp bends in photonic crystal waveguides[J]. Physical Review Letters, 1996, 77(18): 3787-3790. doi: 10.1103/PhysRevLett.77.3787 [9] Notomi M. Theory of light propagation in strongly modulated photonic crystals: refractionlike behavior in the vicinity of the photonic band gap[J]. Physical Review B, 2000, 62(16): 10696-10705. doi: 10.1103/PhysRevB.62.10696 [10] Engelen R J P, Sugimoto Y, Watanabe Y, et al. The effect of higher-order dispersion on slow light propagation in photonic crystal waveguides[J]. Optics Express, 2006, 14(4): 1658-1672. doi: 10.1364/OE.14.001658 [11] Luo C Y, Johnson S, Joannopoulos J, et al. Subwavelength imaging in photonic crystals[J]. Physical Review B, 2003, 68(4): 045115. doi: 10.1103/PhysRevB.68.045115 [12] Jiang L Y, Wu H, Li X Y. Dual-negative-refraction and imaging effects in normal two-dimensional photonic crystals with hexagonal lattices[J]. Optics Letters, 2012, 37(11): 1829-1831. doi: 10.1364/OL.37.001829 [13] Cubukcu E, Aydin K, Ozbay E, et al. Subwavelength resolution in a two-dimensional photonic-crystal-based superlens[J]. Physical Review Letters, 2003, 91(20): 207401. doi: 10.1103/PhysRevLett.91.207401 [14] Li Z Y, Lin L L. Evaluation of lensing in photonic crystal slabs exhibiting negative refraction[J]. Physical Review B, 2003, 68(24): 245110. doi: 10.1103/PhysRevB.68.245110 [15] Zheng X R, Jia B H, Lin H, et al. Highly efficient and ultra-broadband graphene oxide ultrathin lenses with three-dimensional subwavelength focusing[J]. Nature Communications, 2015, 6: 8433. doi: 10.1038/ncomms9433 [16] 李恒一, 王长涛, 罗先刚.用于纳米光刻的超分辨缩小成像平板超透镜研究[J].光电工程, 2011, 38(5): 35-39, 45. doi: 10.3969/j.issn.1003-501X.2011.05.007 Li H Y, Wang C T, Luo X G. Planar hyper lens with demagnification for nanolithography[J]. Opto-Electronic Engineering, 2011, 38(5): 35-39, 45. doi: 10.3969/j.issn.1003-501X.2011.05.007 [17] 高伦, 梁斌明, 王婷, 等.光子晶体负折射效应的电光偏转器[J].光电工程, 2016, 43(5): 77-81. doi: 10.3969/j.issn.1003-501X.2016.05.013 Gao L, Liang B M, Wang T, et al. Electro-optic deflector based on negative refraction effect of photonic crystal[J]. Opto-Electronic Engineering, 2016, 43(5): 77-81. doi: 10.3969/j.issn.1003-501X.2016.05.013 [18] 张学典, 袁曼曼, 常敏, 等.正方形空气孔光子晶体光纤特性分析[J].光电工程, 2018, 45(5): 20-28. doi: 10.12086/oee.2018.170633 Zhang X D, Yuan M M, Chang M, et al. Characteristics in square air hole structure photonic crystal fiber[J]. Opto-Electronic Engineering, 2018, 45(5): 20-28. doi: 10.12086/oee.2018.170633 [19] White J G, Amos W B. Confocal microscopy comes of age[J]. Nature, 1987, 328(6126): 183-184. doi: 10.1038/328183a0 [20] Minsky M. Memoir on inventing the confocal scanning microscope[J]. Scanning, 1988, 10(4): 128-138. doi: 10.1002/sca.4950100403 [21] Egger M D. The development of confocal microscopy[J]. Trends in Neurosciences, 1989, 12(1): 11. doi: 10.1016/0166-2236(89)90149-5 [22] Ziegler D, Papanas N, Zhivov A, et al. Early detection of nerve fiber loss by corneal confocal microscopy and skin biopsy in recently diagnosed type 2 diabetes[J]. Diabetes, 2014, 63(7): 2454-2463. doi: 10.2337/db13-1819 -
Overview
Overview:In recent years, negative refractive index materials (NIMs) have attracted more attention. There are lots of studies on the special characteristics of NIMs such as negative refraction and subwavelength imaging. As a NIM, photonic crystal (PC) can greatly amplify the evanescent waves and break the diffraction limit, the subwavelength resolution can be achieved.
In this paper, The edge length of PC is L=50a. The point source is placed at 0.3 μm below the edge of PC, and its horizontal coordinate is -10 μm. The light path simulated by Rsoft software. The gratings on both sides of the PC increases the transmission of light, eliminating the influence of the reflected light on dual imaging. As the clear two images are achieved, the positional relationship between two images and the point source is obtained. Based on the results, a confocal system with a triangular PC is proposed. Unlike the conventional confocal system, the PC confocal system has a simple structure, and it achieves imaging by negative refraction.
Dual sub-wavelength imaging is achieved clearly by adjusting the grating gap on PC, it eliminates the effects of reflected light. Through varying the wavelength of the point source, a broad spectrum which can achieve sub-wavelength imaging is found. Then adjust the lateral coordinates of the light source points to obtain the positional relationship between the two image points and the light source points. Based on the above results, the photonic crystal confocal system was designed and verified by simulation. The normalized peak value of image1 is increased from 1.104 to 1.326 and the half-width is decreased from 0.461λ to 0.433λ by adjusting the size of the grating air slit; meanwhile, the side spot at image2 is eliminated when the grating air slit is w=0.76a and distance between gratings and air hole is dg=0.1a. The minimum half-width of images is obtained when the incident wavelength is 3.216a, and the wide-spectrum dual subwavelength imaging is achieved when the incident wavelength varies from 3.19a to 3.26 a, which the minimum half-width is less than 0.44λ. In addition, the position formulas of the images and point source are demonstrated, that provides a reference for the precise location of two images. Based on the results, we propose a confocal system that can achieve subwavelength imaging. Compared with the traditional confocal microscope, this structure does not need objective lens. As its focusing and imaging through the negative refraction of PC, the structure is more simple. Furthermore, dual subwavelength imaging can also be used in other aspects.
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Niu Jinke, Liang Binming, Zhuang Songlin, et al. Dual subwavelength imaging based on two-dimensional photonic crystals[J]. Opto-Electronic Engineering, 2019, 46(8): 180577. doi: 10.12086/oee.2019.180577
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Figure 1.
Several EFS contours in the first TE-polarized photonic band of the PC
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Figure 2.
Variable schematic diagram on an enlarged equilateral triangle PC
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Figure 3.
Negative refraction and dual subwavelength imaging of the point source through the equilateral triangle PC without grating and gratings λ=3.216a, the point source is located at 0.3 µm below the PC, and its horizontal coordinate is x=-10 µm. (a) No grating; (b) With gratings; (c) Output values of two energy detectors at the image1 when no grating and with gratings; (d) Output values of two energy detectors at the image2 when no grating and with gratings
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Figure 4.
The half-width and peak value of image1 various with (a) w and (b) dg
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Figure 5.
The half-width of the images when the wavelength of point source from 3.11a to 3.32a
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Figure 6.
Point source moves from 0 to -10 µm. (a) The half-width of images; (b) Position of images
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Figure 7.
Confocal system based on PC. (a) Confocal diagram; (b) Path of laser; (c) Path of fluorescence
