Adaptive focusing enables to focus light through opaque curtains. The maximum resolution of this process is limited by the effective numerical aperture of the system: the span of angles which contribute to the focusing. In a recent paper , we demonstrate, by exploiting a custom spatial filter, how it is possible to select, between the many light paths contributing to the adaptive focusing, the ones which provide the higher numerical aperture. This optical selection effectively improves the resolution of the adaptive focusing in the weak scattering regime.
Read more on the Scientific Reports Article
or on the web paper.
In a speckle pattern, light is organized in disordered fashion with maxima and minima of intensity. The multiple wave components underlying an inhomogeneous optical rogue wave may give rise to exceptional maxima of intensity which are similar to unpredictable rogue waves appearing from nowhere in the ocean. Here, we demonstrate that the inhomogeneity-driven optical rogue waves may be fully tailored through adaptive optics and that may be also activated behind fully reflective obstacles.
In photonics, disorder is usually seen as a bad feature decreasing the efficiency of optical elements and driving light far from your target.
In this paper we demonstrate that the reverse is possible: disorder transforms two de focusing-plastics into a self-focusing metamaterial.
By exploiting a phenomenon named Transversal Anderson localization it is possible to exploit scattering events to constrain light into a tiny space, and exploit very cheap disordered optical to bring information at large distances.
By putting together Transverse localization and Nonlinearity it si possible to achieve complete control of a light beam, defining the degree of localization and its position.
I’have been happy to part of the “Light Localisation and Lasing” team: a comprehensive book on light, lasing and disorder.
Out in January 2015!
“The properties of quasi-random and random photonic systems have been extensively studied over the last two decades, but recent technological advances have opened new horizons in the field, providing better samples and devices. New optical characterization techniques have enhanced understanding of the novel and fundamental properties of these systems. This book examines the full hierarchy of these systems, from 1D to 2D and 3D, from photonic crystals and random microresonator chains to quasi crystals.”
In a nonlinear optical material, the refractive index varies with the optical intensity. In general thermal nonlinearity produces a de-focusing effect. In this paper we demonstrate that disorder changes the terms around and transform a de-focusing nonlinearity into a focusing one. When the thermal nonlinearity is activated, the two materials composing the optical fiber respond differently and the refractive index mismatch increases, enhancing the strength of the transversal Anderson localization. In a nutshell we demonstrate a nonlinearly enhanced transverse Anderson localization.
Our paper on Anderson fibers l fibers controlled with adaptive optics is explained on the “Corriere della sera online”.
Anderson localization is a regime in which diffusion is inhibited and waves (also electromagnetic waves) get localized. In a recent paper on Nat. Commun. we exploit adaptive optics to achieve focusing in disordered optical fibres in the Anderson regime.
Anderson localization means immoble waves in a disordered structure. We demonstrate that this paradigm is revolutionized when nonlinearity and nonlocality tak part to the game: Modes start to migrate when they “feel heat” generated by light absorbed along the fiber. See more on the journal article.
In a recent paper we summarized the latest advances in the random lasing control. Our contribution has been selected to participate to the cover selection in the december OPN issue… arriving second unfotunately.
A Random laser is an ensemble of strongly interacting modes. In a paper on Nat. Commun. we demonstrate the possibility to exploit the inter mode interaction to achieve long range control of modes producing amplification and frequency switchinf between resonances distant up to 15 microns into a completely disordered structure