Disorder is a pervasive characteristic of natural systems, offering a wealth of non-repeating patterns. In this study, we present a novel storage method that harnesses naturally-occurring random structures to store an arbitrary pattern in a memory device. This method, the Stochastic Emergent Storage (SES), builds upon the concept of emergent archetypes, where a training set of imperfect examples (prototypes) is employed to instantiate an archetype in a Hopfield-like network through emergent processes. We demonstrate this non-Hebbian paradigm in the photonic domain by utilizing random transmission matrices, which govern light scattering in a white-paint turbid medium, as prototypes. Through the implementation of programmable hardware, we successfully realize and experimentally validate the capability to store an arbitrary archetype and perform recognition at the speed of light. Leveraging the vast number of modes excited by mesoscopic diffusion, our approach enables the simultaneous storage of thousands of memories without requiring any additional fabrication effort, moreover these memories can be grouped to realize higher level classes thus realizing patterns classification.
Blind-Structured Illumination Microscopy (blind-SIM) enhances the optical resolution without the requirement of nonlinear effects or pre-defined illumination patterns. It is thus advantageous in experimental conditions where toxicity or biological fluctuations are an issue. Here we introduce a custom convolutional neural network architecture for blind-SIM: BS-CNN. This deconvolution algorithm, based on a 3D correlation kernel, can be employed strategically together with Scattering Assisted Imaging (SAI), thus enhancing resolution also in turbid media. Indeed, in standard imaging systems spatial resolution that is ultimately dictated by the Numerical Aperture (NA) of the illumination/collection optics. In biological tissues, the resolution is strongly affected by scattering, which limits the penetration depth to tenths of microns. SAI exploit the properties of speckle patterns embedded into a strongly scattering matrix to illuminate the sample at high spatial frequency content. Combining adaptive optics with our deconvolution algorithm, we obtain a resolution improvement of 2.17 and high fidelity in the form of artifacts reductions. This multi technique approach can find applications in the retinal investigation, where numerical aperture is biologically limited by the eye iris thus limited to a maximum o 0.25. SAI plus BS-CNN can be potentially applied to the eye providing images with increased effective resolution.
Spin Glasses (SG) are paradigmatic models for physical, computer science, biological and social systems. The problem of studying the dynamics for SG models is NP-hard, i.e., no algorithm solves it in polynomial time. Here we implement the optical simulation of an SG, exploiting the N segments of a Digital Micromirror Device to play the role of the spin variables, combining the interference at downstream of a scattering material to implement the random couplings and measuring the transmitted light intensity to retrieve the system energy. We demonstrate that This optical platform beats digital computation for large-scale simulation (N<12000).
Spin Glasses (SG) are paradigmatic models for physical, computer science, biological and social systems. The problem of studying the dynamics for SG models is NP-hard, i.e., no algorithm solves it in polynomial time. Here we implement the optical simulation of an SG, exploiting the N segments of a Digital Micromirror Device to play the role of the spin variables, combining the interference at downstream of a scattering material to implement the random couplings and measuring the transmitted light intensity to retrieve the system energy. We demonstrate that This optical platform beats digital computation for large-scale simulation (N>12000).
Standard imaging systems provide a spatial resolution that is ultimately dictated by the numerical aperture. In biological tissues, the resolution degraded by scattering which limits the imaging at a depth. Here, we exploit the properties of speckle patterns embedded into a strongly scattering matrix to illuminate the sample at high spatial frequency content. Combining adaptive optics with a custom deconvolution algorithm, we obtain a resolution improvement of a factor < 2.5. Our Scattering Assisted Imaging (SAI, M. Leonetti et al., Sci. Rep. 9:4591 (2019)) provides an effective solution to increase the resolution when long working distance optics are needed.
Standard imaging systems provide a spatial resolution that is ultimately dictated by the numerical aperture (NA) of the illumination and collection optics. In biological tissues, the resolution is strongly affected by scattering, which limits the penetration depth to a few tenths of microns. Here we exploit the properties of speckle patterns embedded into a strongly scattering matrix to illuminate the sample at high spatial frequency content. Combining illumination performed through a Digital Micromirror Device(DMD) and a custom deconvolution algorithm, we obtain an increase in the transverse spatial resolution by a factor of 2.5 with respect to the natural diffraction limit.
The combined use of a wavefront modulator and a scattering medium forms an "opaque lens" which forces the light to focus tightly. The adaptive focus has the same shape as the correlation function of the original speckle pattern and it can be generated at defined positions with resolution up to hundreds of nanometers. We have demonstrated that manipulating the speckle pattern spatial components can structure the shape of the focus. Exploiting selectively spatial-frequencies from the speckle components we realized opaque lenses able to produce sub-correlation foci and Bessel beams.
By compensating the random phase delay acquired while a light beam crosses a scattering curtain, it is possible to address the light at selected target position beyond the obstacle. An opaque lens can produce foci with a resolution higher than conventional optics if a strongly scattering medium is exploited. In practice, subwavelength resolution is obtained only for weakly transmitting samples. Herein we present a method which allows obtaining tiny bright optical spots even in presence of a minimum amount of scattering (semi-transparent media) in the beam path. Using a High-Pass spatial filter we block the pseudo-ballistic components of the transmitted beam, we are able to gather light on a spot with a diameter which is one third of the typical speckle grain in absence of the filter.
A random laser is formed by a haphazard assembly of nondescript optical scatters with optical
gain. Multiple light scattering replaces the optical cavity of traditional lasers and the interplay
between gain, scattering and size determines its unique properties. Random lasers studied till
recently, consisted of irregularly shaped or polydisperse scatters, with some average scattering
strength constant across the gain frequency band. Photonic glasses can sustain scattering resonances
that can be placed in the gain window, since they are formed by monodisperse spheres
[1]. The unique resonant scattering of this novel material allows controlling the lasing color via
the diameter of the particles and their refractive index. Thus a random laser with a priori set
lasing peak can be designed [2].
A special pumping scheme that enables to select the number of activated modes in a random
laser permits to prepare RLs in two distinct regimes by controlling directionality through the
shape of the pump [3]. When pumping is essentially unidirectional, few (barely interacting)
modes are turned on that show as sharp, uncorrelated peaks in the spectrum. By increasing
angular span of the pump beams, many resonances intervene generating a smooth emission
spectrum with a high degree of correlation, and shorter lifetime. These are signs of a phaselocking
transition, in which phases are clamped together so that modes oscillate synchronously.
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