Category Archives: Paper

Paper WP4

All-fiber wavefront shaping by transmission matrix engineering

Shachar Resisi, Yehonatan Viernik, Sebastien M. Popoff, Yaron Bromberg, arxiv (2019)

In the past 10 years, many applications were successfully demonstrated for wavefront shaping in multimode fibers, from endoscopic to telecommunications through optical tweezers. However, these techniques require to modulate the incident field using free space modulators. In the present paper, we introduce a new approach that relies on modulating the transmission matrix itself by applying changes that modify its boundary conditions. Using an all-fiber apparatus, focusing light at the distal end of the fiber and conversion between fiber modes is demonstrated. Since in this approach the number of degrees of control can be larger than the number of fiber modes, it allows simultaneous control over multiple inputs and multiple wavelengths.

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Paper WP1

Turning Optical Complex Media into Universal Reconfigurable Linear Operators by Wavefront Shaping

Maxime W. Matthès, Philipp del Hougne, Julien de Rosny, Geoffroy Lerosey and Sébastien M. Popoff, Optica, 6, 4 (2019)

Performing linear operations using optical devices is a crucial building block in many fields ranging from telecommunication to optical analogue computation and machine learning. For many of these applications, key requirements are robustness to fabrication inaccuracies and reconfigurability. Current designs of custom-tailored photonic devices or coherent photonic circuits only partially satisfy these needs. Here, we propose a way to perform linear operations by using complex optical media such as multimode fibers or thin scattering layers as a computational platform driven by wavefront shaping. Given a large random transmission matrix (TM) representing light propagation in such a medium, we can extract a desired smaller linear operator by finding suitable input and output projectors. We discuss fundamental upper bounds on the size of the linear transformations our approach can achieve and provide an experimental demonstration. For the latter, first we retrieve the complex medium’s TM with a non-interferometric phase retrieval method. Then, we take advantage of the large number of degrees of freedom to find input wavefronts using a Spatial Light Modulator (SLM) that cause the system, composed of the SLM and the complex medium, to act as a desired complex-valued linear operator on the optical field. We experimentally build several 16×16 complex-valued operators, and are able to switch from one to another at will. Our technique offers the prospect of reconfigurable, robust and easy-to-fabricate linear optical analogue computation units.

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Paper Talk

Wavefront shaping in complex media: From the compensation to the harnessing of disorder [CLEO 2017]

Sébastien M. Popoff, CLEO, (2017)

In the past ten years, many techniques were developed to control light propagation in complex transmission media using spatial light modulators. It involved applications in numerous fields [1-2] including biomedical imaging and therapy, fiber endoscopy, cryptography, optical micromanipulation, optical spectroscopy, telecommunications and random lasers and also served as a tool for fundamental studies of light propagation in complex environments.

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