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(a) SEM image of the glass optical fiber with random air-holes. For ease of viewing, the polymer coating has been removed. (b) Refractive index profile used in our simulations.
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We report the first observation of transverse Anderson localization in a glass optical fiber. The strong localization happens near the outer boundary of the fiber and no trace of localization is observed in the central regions. However, these observations complement previous reports that the boundary of a disordered medium has a de-localizing effec...
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... cross-sectional SEM image of the disordered porous optical fiber is shown in Fig. 1(a), which also provides a good estimate of the refractive index profile of the fiber; the light gray background matrix is glass and the black random dots represent the air-holes. The diameter of the fiber is confirmed to be about 250 μm and the average air fill-fraction is about 5.5% with the air-hole diameters varying between about ...
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... finite difference beam propagation method (FD-BPM) was used to carry out the simula- tions [13]. The refractive index profile is extracted from the SEM image of the fiber in Fig. 1(a) and is directly used in the FD-BPM program; the refractive index profile used in our simulations is shown in Fig. 1(b). Fig. 2. The experimental measurement of the near-field intensity when the beam is launched near the center of the fiber, where no localization is observed. Figure 2 shows a typical result from launching of the beam ...
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... finite difference beam propagation method (FD-BPM) was used to carry out the simula- tions [13]. The refractive index profile is extracted from the SEM image of the fiber in Fig. 1(a) and is directly used in the FD-BPM program; the refractive index profile used in our simulations is shown in Fig. 1(b). Fig. 2. The experimental measurement of the near-field intensity when the beam is launched near the center of the fiber, where no localization is observed. Figure 2 shows a typical result from launching of the beam (405 nm wavelength) into the center of the fiber. It is clear that the disorder is not sufficient to clamp the beam ...
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... repeated the same procedure outlined above in our simulations, using the refractive in- dex profile shown in Fig. 1(b), and collected 100 separate near-field intensity profiles, using incident beams launched at different positions near the outer boundary of the fiber. The beam localization for four different incident spots near the outer boundary are shown in Fig. 4; again, in each case, the localized spot consists of multiple peaks, which are located ...
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Citations
... On the other hand, the input-output relationship in MMFs is far deviated from a point-to-point transmission due to the multimode interference. The recently proposed glass-air Anderson localizing optical fibers (GALOFs) [25][26][27][28][29][30][31][32][33] provide a promising alternative. With a disordered arrangement of air holes embedded in a silica matrix, GALOFs achieve local confinement of light and high sampling densities (~10 mode/µm 2 ) simultaneously 34 due to the transverse Anderson localization (TAL) 35,36 . ...
Recent years have witnessed the tremendous development of fusing fiber-optic imaging with supervised deep learning to enable high-quality imaging of hard-to-reach areas. Nevertheless, the supervised deep learning method imposes strict constraints on fiber-optic imaging systems, where the input objects and the fiber outputs have to be collected in pairs. To unleash the full potential of fiber-optic imaging, unsupervised image reconstruction is in demand. Unfortunately, neither optical fiber bundles nor multimode fibers can achieve a point-to-point transmission of the object with a high sampling density, as is a prerequisite for unsupervised image reconstruction. The recently proposed disordered fibers offer a new solution based on the transverse Anderson localization. Here, we demonstrate unsupervised full-color imaging with a cellular resolution through a meter-long disordered fiber in both transmission and reflection modes. The unsupervised image reconstruction consists of two stages. In the first stage, we perform a pixel-wise standardization on the fiber outputs using the statistics of the objects. In the second stage, we recover the fine details of the reconstructions through a generative adversarial network. Unsupervised image reconstruction does not need paired images, enabling a much more flexible calibration under various conditions. Our new solution achieves full-color high-fidelity cell imaging within a working distance of at least 4 mm by only collecting the fiber outputs after an initial calibration. High imaging robustness is also demonstrated when the disordered fiber is bent with a central angle of 60°. Moreover, the cross-domain generality on unseen objects is shown to be enhanced with a diversified object set.
... This was first realized [251] by the stack-and-draw method from two polymers with different refractive indices [ Fig. 38(c)]. Later, disordered glass-air fibers with larger refractive index contrast [ Fig. 38(b,d)] were fabricated [244,252,253]. Transverse scattering and interference of light results in transverse localization, similar to Anderson localization in a 2D disordered structure. ...
Light transport in a highly multimode fiber exhibits complex behavior in space, time, frequency and polarization, especially in the presence of mode coupling. The newly developed techniques of spatial wavefront shaping turn out to be highly suitable to harness such enormous complexity: a spatial light modulator enables precise characterization of field propagation through a multimode fiber, and by adjusting the incident wavefront it can accurately tailor the transmitted spatial pattern, temporal profile and polarization state. This unprecedented control leads to multimode fiber applications in imaging, endoscopy, optical trapping and microfabrication. Furthermore, the output speckle pattern from a multimode fiber encodes spatial, temporal, spectral and polarization properties of the input light, allowing such information to be retrieved from spatial measurements only. This article provides an overview of recent advances and breakthroughs in controlling light propagation in multimode fibers, and discusses newly emerging applications.
... Another novel route to waveguiding stems from the work of Anderson, for which he shared the 1977 Nobel Prize in Physics for work associated with the absence of diffusion in random structures [432]. Such "Anderson localization" was first realized in a glass optical fiber in 2012 [433], and subsequently shown to enable high fidelity image transmission. ...
... The experimental studies of Anderson localization of light are complicated by competition between Anderson localization and diffusion/absorption [6,7]. Nevertheless, fruitful experiments on the so-called transverse Anderson localization of light were carried out CONTACT R. S. Puzko roman998@mail.ru in quasi-1D and quasi-2D systems [8][9][10]. These experiments deal with one-dimensional and two-dimensional arrays of coupled waveguides. ...
The propagation of light through a disordered layered system in the Anderson localization regime is studied. The light propagation is accompanied by Anderson localization and phase randomization, which are generally related processes. This research is aimed at a detailed study of phase randomization. Particularly, the phase randomization approximation is tested numerically. It is shown that the distribution function of the transmission coefficient phase tends to stationary distribution as the number of layers increases. However, the stationary distribution is generally a non-uniform one contrary to the widely used assumption. The exponential convergence to the stationary distribution allows an unambiguous definition of the length scale of phase randomization.
... On the other hand, the input-output relationship in MMFs is far deviated from a point-to-point transmission due to the multimode interference. The recently proposed glass-air Anderson localizing optical fibers (GALOFs) 25,26,27,28,29,30,31,32,33 provide a promising alternative. With a disordered arrangement of air holes embedded in a silica matrix, GALOFs achieve local confinement of light and high sampling densities (~10 mode/µm 2 ) simultaneously 34 due to the transverse Anderson localization (TAL) 35,36 . ...
Recent years have witnessed the tremendous development of fusing fiber-optic imaging with supervised deep learning to enable high-quality imaging of hard-to-reach areas. Nevertheless, the supervised deep learning method imposes strict constraints on fiber-optic imaging systems, where the input objects and the fiber outputs have to be collected in pairs. To unleash the full potential of fiber-optic imaging, unsupervised image reconstruction is in demand. Unfortunately, neither optical fiber bundles nor multimode fibers can achieve a point-to-point transmission of the object with a high sampling density, as is a prerequisite for unsupervised image reconstruction. The recently proposed disordered fibers offer a new solution based on the transverse Anderson localization. Here, we demonstrate unsupervised full-color imaging with a cellular resolution through a meter-long disordered fiber in both transmission and reflection modes. The unsupervised image reconstruction consists of two stages. In the first stage, we perform a pixel-wise standardization on the fiber outputs using the statistics of the objects. In the second stage, we recover the fine details of the reconstructions through a generative adversarial network. Unsupervised image reconstruction does not need paired images, enabling a much more flexible calibration under various conditions. Our new solution achieves full-color high-fidelity cell imaging within a working distance of at least 4 mm by only collecting the fiber outputs after an initial calibration. High imaging robustness is also demonstrated when the disordered fiber is bent with a central angle of 60{\deg}. Moreover, the cross-domain generality on unseen objects is shown to be enhanced with a diversified object set.
... The disordered optical fibers with silica and air (silica~1.5) [10] have been studied and experimentally proven to have more robust designs. It was found that the external excitation and the width will affect the reliability of the conclusion in the above research. ...
Disordered waveguides mediated by transverse Anderson localization (TAL) can be used as mode division multiplexing system. The whole cross-section of the disordered waveguides is covered by all localized modes, which function as independent space channels. The localized modes are independent of the boundary and external excitation. The numerical results reveal that the average width tends to be steady in one particular realization of the disordered waveguide with a sufficient number of localized modes. In this paper, we proposed that localization length can be measured by the average width of localized modes. Besides, we explore the impact of the disordered waveguide design parameters, such as refractive index contrast, fill-fraction, and feature size, on the average width of localized modes.
... Moreover, the eventual adoption of TALOF in real world use cases hinges upon the availability of an industrially scalable fabrication process. To date, using predominantly the stack-and-draw technique, first polymer-polymer 12 , then glass-glass [13][14][15] , and air-glass TALOFs 11,16,17 have been manufactured. More recently, femtosecond laser-writing has also been employed 18 , but all of the above fabrication methods are laborintensive and cannot be scaled to an industrial process. ...
Propagation of light by Anderson localization has been demonstrated in micro-nano-structured fibers. In this work, we introduce a phase separated glass Anderson localization optical fiber for quantum applications. By using a spontaneous parametric down-conversion source, multi-photon detection with a single-photon avalanche diode array camera, and signal post-processing techniques, we demonstrate quantum light transport, where spatial correlations between photon pairs are preserved after propagation. In order to better understand and improve light transport, we study light localization, observing a dependence on wavelength. Our results indicate that the proposed phase separated fiber may become an effective platform for quantum imaging and communication. Anderson localization, a strong localization effect that prevents wave diffusion, is fundamentally important in manipulating wave propagation in a disordered medium. This work uses a phase separated glass Anderson localization optical fiber and demonstrates quantum light transport, which shows the potential for transmission of high dimensional quantum information, thereby enabling quantum imaging and quantum communication applications.
... This fiber was used for detailed studies on the characteristics of TAL in disordered optical fibers, spatial beam multiplexing, and image transport [9][10][11]. Shortly after, the first silica TALOF was reported by drawing a porous satin quartz glass into a fiber with a transversely random index profile [12]. Since then, several other groups have also successfully observed TAL in various optical fiber platforms [13][14][15]. ...
We investigate and report the optical and laser characteristics of a ytterbium-doped transverse Anderson localizing optical fiber to develop a fundamental understanding of the light propagation, generation, and amplification processes in this novel fiber. Ultimately, the goal based on the measurements and calculations conducted herein is to design and build a random fiber laser with a highly directional beam. The measurements are based on certain observations of the laser pump propagation and amplified spontaneous emission generation in this fiber. Judicious approximations are used in the propagation equations to obtain the relevant desired parameters in simple theoretical fits to the experimental observations, without resorting to speculations based on the intended construction from the fiber preform.
... 130 The extension to optical fibers took time due largely to the lack of an application. Since the realization of the first glass TALOF in 2012, 131 there has been a steady stream of progress. Materially, silica remains the dominant material, for reasons noted previously, with both CVD 132 and stack-and-draw fabrication methods prevailing. ...
Glass optical fibers have reached a scale and commercial maturity that few, if any, other material and form can claim. Furthermore, optical fibers not only enable a remarkably broad range of applications but are, themselves, unique tools for fundamental studies into light‐matter interactions. That said, despite such ubiquity and global impact, increasing demands from existing systems, coupled with new expectations from novel emerging technologies, are necessitating a remarkably creative renaissance in optical fiber materials, structures, and processing methodologies. This paper, a follow‐on to a previous historical retrospective [Ballato and Dragic, Int. J. Appl. Glass Sci. 7, 413 (2016)], discusses current and future trends, recent advances in optical fiber materials, processing and properties, and muses about their forthcoming prospects and areas for further study and development. Specifically, optical fibers employed in present and future communications, sensors, and laser systems are discussed along with material innovations that could yield revolutionary advances in performance or manufacturability.
... Later, it was realized that robust samples could be obtained if the refractive index contrast in the disordered medium is further increased [28]. A porous optical fiber, made of silica glass-air with a fill fraction being below the optimal value of 50 %, was designed and produced to strongly localize light waves in the transverse plane [29]. Even in a three-dimensional disordered medium, the transverse Anderson localization has been reported both experimentally and theoretically [30,31]. ...
Spontaneous emission dynamics of rhodamine 6G molecules coupled into transverse Anderson localized modes in a hyperbolic waveguide is investigated using time-resolved experiments. Four hyperbolic waveguides are simultaneously formed inside a deltoid-shaped fused-silica microtube via the capillary effect. The disordered photonic environment consisting of a rhodamine-doped polymeric material with randomly distributed air inclusions is attributed to localize photons at various resonant wavelengths of the quasi-optical cavities, randomly positioned throughout the guiding medium. The hyperbolic waveguides allow obtaining a single, double, and multimode resonant structures, trapping photons at various frequencies as explored in the form of sharp spectral resonances within the photoluminescence spectrum bandwidth of the dye molecules. Experimental results reveal that the coupling of the fluorescent emitters into multimode localizations in each hyperbolic waveguide corresponds to obtaining quasi-optical cavities at various resonant frequencies, which alter the emission characteristics of the emitters distinctively. The spontaneous emission rate of the dye molecules coupled into the isolated transverse Anderson localized modes is observed to increase by a factor of up to 6.7, thus, the vacuum fluctuations at certain resonant wavelengths are considerably enhanced.
