Experimental evidence of super-resolution better than<i>λ</i>/105 with positive refraction

Miñano, Juan C.; Sánchez‐Dehesa, José; González, Juan Carlos; Benı́tez, Pablo; Grabovičkić, Dejan; Carbonell, J.; Ahmadpanahi, Hamed

doi:10.1088/1367-2630/16/3/033015

Cited by 18 publications

(23 citation statements)

References 18 publications

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“…Much of the controversy has centred on the role of detection in perfect imaging-the perfect transfer of the electromagnetic field from object to image is only possible if the image is detected. Another important point was noticed in a computer simulation [18] and a subsequent experiment [19] by Miñano et al: at specific resonance frequencies of the instrument a point detector is sensitive to displacements of a point source with an accuracy that is significantly better than the diffraction limit. No physical explanation for this feature has been found yet.…”

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confidence: 99%

A simple model explaining super-resolution in absolute optical instruments

et al. 2015

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We develop a simple, one-dimensional model for super-resolution in absolute optical instruments that is able to describe the interplay between sources and detectors. Our model explains the subwavelength sensitivity of a point detector to a point source reported in previous computer simulations and experiments (Miñano 2011 New J. Phys.13 125009; Miñano 2014 New J. Phys.16 033015).Perfect imaging with positive refraction [1] has been subject to considerable controversy [2-17] that has given important insight into the matter. Much of the controversy has centred on the role of detection in perfect imaging-the perfect transfer of the electromagnetic field from object to image is only possible if the image is detected. Another important point was noticed in a computer simulation [18] and a subsequent experiment [19] by Miñano et al: at specific resonance frequencies of the instrument a point detector is sensitive to displacements of a point source with an accuracy that is significantly better than the diffraction limit. No physical explanation for this feature has been found yet. Here we develop a simple model that captures both issues, the role of the detection and the role of the resonance, which allows us to deduce both physical explanations and analytic expressions for the sensitivity.Perfect-imaging devices with positive refraction are absolute optical instruments [20] with closed loops of rays [21,22]. The archetype of such instruments is Maxwell's fish eye [23] where light goes in circles and where all light circles originating from any given point intersect at a corresponding image point. Luneburg [24] discovered a geometrical picture that explains the properties of Maxwell's fish eye: the refractive-index profile of Maxwell's device appears to light as the surface of a sphere in two-dimensional (2D) and hypersphere in threedimensional (3D) space; light propagates in the medium of the fish eye as if it were confined to spherical surfaces. The geodesics on the sphere appear as the circles of light (by stereographic projection), object and image correspond to antipodal points on the sphere where geodesics intersect. Let us consider the simplest case of perfect imaging, the one-dimensional (1D) sphere: the circle (figure 1). Imagine that light is confined to a circle, say a fibre loop or ring resonator. Here light can go in only two directions, to the right or to the left. An 'image' is formed when the two rays meeting have the same phase, which happens when both are antipodal. Light is coupled in and out of the circle by two 1D channels that represent the source and the detector. These 1D channels are idealizations of the cables used for injecting and extracting radiation in the simulation [18] and experiment [19]. Clearly, this 1D system represents a rather primitive model, but it is going to reproduce the findings of the experiment [19], the model is simple, but not too simple.We are going to show how a point detecter is able to sense minute displacements of a point source. Note that this is not imaging in the ...

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A simple model explaining super-resolution in absolute optical instruments

et al. 2015

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“…We should also note that the 'super-resolution' found in SGW is at near field in their simulation [22,23] and experiment [24] (i.e., the closest distance between the source and the physical waveguiding structure is less than the wavelength). In near-field, a super-resolution can be easily achieved by some microscope technologies (e.g., using a grating in the near field to make the conversion between the evanescent and propagating waves in a structured illumination microscopy [27], and nearfield scanning optical microscope [28]).…”

Section: About the 'Super-resolution' In A Spherical Geodesic Waveguidementioning

confidence: 93%

“…Later Miñano's group also claimed that λ/500 and λ/3000 super-resolution can be achieved in the SGW for only some discrete frequencies by numerical simulations [22,23]. In 2014, they claimed their experiment of the SGW could achieve a λ/105 resolution for a set of specific frequencies and loads [24]. Actually the 'super-resolution' found by Miñano in an SGW is essentially different from the perfect image in an MFEL/MFEM claimed by Leonhardt due to the following reasons:…”

Section: About the 'Super-resolution' In A Spherical Geodesic Waveguidementioning

confidence: 99%

“…In an SWG, the super-resolution is defined as 'the minimum displacement of a point receptor that causes a drop of the power to 10% of the value received in the initial position.' [24]. The super-resolution claimed by Miñano's group in an SGW is just a position sensor with a high sensitivity at some discrete frequencies.…”

Section: About the 'Super-resolution' In A Spherical Geodesic Waveguidementioning

confidence: 99%

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Can Maxwell's Fish Eye Lens Really Give Perfect Imaging? Part Iii. A Careful Reconsideration of the ``Evidence for Subwavelength Imaging With Positive Refraction''

He¹,

Sun²,

Guo³

et al. 2015

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Abstract-Many scientists do not believe that Maxwell's fish eye mirror (MFEM) can provide perfect imaging even if there is a drain array around the imaging points. However, one microwave experiment found a case where a 0.2λ resolution could be achieved in an MFEM experiment [1]. In this paper, we show that the MFEM cannot resolve two imaging points at such a subwavelength resolution in most cases even in the presence of a drain array, and an extraordinary case of subwavelength imaging requires a particular phase difference between two coherent sources. Both numerical simulations and experimental results show that the phase difference of two subwavelength-distanced coherent sources greatly influences the field distribution around the drain array. In very few cases (when the phase difference of the two sources is chosen to be a very specific value), we might resolve the image points in the drain array under the assumption that the power absorbed by the scanning cable on the left side of the drain array should be symmetric to that on the right side of the drain array [1]. However, in most cases, we cannot obtain a super-resolution imaging, as other drains around the image points will greatly influence the imaging. We also note that the experiment assumed that the power absorbed by the scanning cable on the left and the right sides of the drain array is symmetric is not correct for the experiment reported in [1], as the drain array itself is not symmetric. The highly non-symmetric distribution of the absorbed power is also verified by our simulation and experimental results. The experimental "result" of resolving two image peaks could potentially be recovered using only a single image peak, which demonstrates the wrong assumption of mirror symmetry. Comparisons and comments on perfect passive drains, "super-resolution" in a spherical geodesic waveguide, and time reverse imaging are also given.

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“…This drawback, known as the "Abbé limit, has long been the foremost barrier to high-resolution imaging, until the early 2000s when Pendry [1] showed that an optical lens with a negative index can restore the evanescent waves issued from the source allowing then for the subdiffraction imaging and for a resolution better than half the wavelength at the focus. From then on, several devices based on this principle, including superlensing photonic crystals [2], optical superlenses [3], hyperlenses [4,5], metalenses [6][7][8][9], and Maxwell fish eyes [10,11], have been proposed. These artificial devices either restore the evanescent waves [1][2][3], or convert them to propagative waves owing to a subwavelength grating inserted in between the object and the objective of a regular optical microscope [4][5][6].…”

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confidence: 99%