Full-Field Subwavelength Imaging Using a Scattering Superlens

Abstract

Light-matter interaction gives optical microscopes tremendous versatility compared with other imaging methods such as electron microscopes, scanning probe microscopes, or x-ray scattering where there are various limitations on sample preparation and where the methods are inapplicable to bioimaging with live cells. However, this comes at the expense of a limited resolution due to the diffraction limit. Here, we demonstrate a novel method utilizing elastic scattering from disordered nanoparticles to achieve subdiffraction limited imaging. The measured far-field speckle fields can be used to reconstruct the subwavelength details of the target by time reversal, which allows full-field dynamic super-resolution imaging. The fabrication of the scattering superlens is extremely simple and the method has no restrictions on the wavelength of light that is used. DOI: 10.1103/PhysRevLett.113.113901 PACS numbers: 42.25.Fx, 42.25.Kb, 42.40.-i Since the first experimental demonstration of the nearfield scanning optical microscope (NSOM) [1], various methods to probe the near fields have been proposed. The field of bioimaging has shown the largest number of new techniques due to the direct need to use visible wavelengths and observation in a nonvacuum environment. Although the currently developed methods are comprised of multiple unique ideas, the common goal of all super-resolution techniques is the effective delivery of the high spatial frequency components of the target object's angular spectrum, which are evanescent and are restricted to distances smaller than the wavelength of light from the object of interest.Here, we propose to use multiple scattering in turbid media to deliver the near-field wave vectors to the observable far field, which allows optical subdiffraction limited imaging using conventional optics. Similar to the hyperlens [2] or in structured illumination [3] where a specific nearfield mode corresponds to a corresponding far-field mode, multiple scattering induces the mixture and transfer between the far and near fields. Because elastic scattering is described by Maxwell's equations, which has time-reversal symmetry, multiple scattering of light exhibits time-reversal symmetry no matter how complicated and random each scattering event is. This property has allowed fascinating demonstrations such as the removal of inhomogeneity in the generation of photon echoes [4] or perfect absorption which is the opposite of lasing [5]. In imaging, multiple scattering and the principle of time reversal have been capitalized in reconstructing the incident field prior to multiple scattering [6][7][8]. In the microwave region, it has also been shown that scattering materials placed in the near field of a target object can scatter the near fields into propagating farfield components [9,10]. More recently, similar phenomena have been shown numerically in the optical region utilizing subwavelength coupled resonators [11] and subwavelength imaging has been demonstrated by using the combination of the memory effect and a hig...

Feedback-based wavefront shaping

“…Once the TM is known, it can be inverted to descramble any transmitted image [19,22,43,47,49]. Other promising computational approaches are under development, such as the use of spectral encoding [98].…”

“…1 is replaced by a camera, it is possible to measure multiple rows of the TM at once [43]. This technique is extremely powerful as it allows for transmitting images [47,48], direct imaging [22,49], raster scanning fluorescence microscopy [16], and maximizing the transmission to a given large-area target [41]. Also, it allows a determination of the eigenvalues of the TM [39, 41, 43], the statistical distribution of which is of fundamental interest in mesoscopic scattering theory (e. g [31].).…”

“…The field of wavefront shaping is under rapid development, and proof-of-concept applications in deep tissue microscopy [12][13][14][15], endoscopy [16][17][18][19], optical trapping [20], super-resolution imaging [21,22], nano-positioning [23], and cryptography [24][25][26] have been demonstrated.…”

Scattering Optical Elements: Stand-Alone Optical Elements Exploiting Multiple Light Scattering

“…15,28,29 When a coherent beam illuminates a disordered medium consisting of random nanoparticles, it generates random speckle patterns. The size of granular of the speckle patterns are smaller than the diffraction limit because subwavelength optical structures of the disordered medium can effectively couple the incident far-field components to the scattered near-field components.…”

[Invited Paper] Review: 3D Holographic Imaging and Display Exploiting Complex Optics

“…In the spatial domain, the input bases correspond to point sources at different spatial locations 32) . In the spatial frequency domain, the input bases correspond to plane waves with different propagation angles 36) .…”