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Babak Rahmani

Cette personne a quitté l’EPFL

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Publications associées (22)

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Learning of physical systems: from inference to control

Babak Rahmani

To characterize a physical system to behave as desired, either its underlying governing rules must be known a priori or the system itself be accurately measured. The complexity of full measurements of the system scales with its size. When exposed to real-w ...

EPFL2022

Learning to image and compute with multimode optical fibers

Demetri Psaltis, Christophe Moser, Babak Rahmani, Ugur Tegin, Ilker Oguz, Jih-Liang Hsieh

Multimode fibers (MMF) were initially developed to transmit digital information encoded in the time domain. There were few attempts in the late 60s and 70s to transmit analog images through MMF. With the availability of digital spatial modulators, practica ...

WALTER DE GRUYTER GMBH2022

Terahertz Quarter Wave-Plate Metasurface Polarizer Based on Arrays of Graphene Ribbons

Babak Rahmani

We propose a novel graphene-dielectric-based meta-surface for manipulating the polarization of the incident light in the terahertz regime. The proposed structure comprised two orthogonally oriented periodic array of graphene ribbons (PAGRs) which are separ ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2019

Imaging through multimode fibers using deep learning: The effects of intensity versus holographic recording of the speckle pattern

Demetri Psaltis, Christophe Moser, Damien Claude-Marie Loterie, Eirini Kakkava, Babak Rahmani, Ugur Tegin, Navid Borhani, Georgia Konstantinou

Information transmission through multimode fibers (MMFs) has been a topic of great interest for many years. Deep learning algorithms have been applied successfully to MMFs in particular to fiber endoscopy. In this work, we show how Deep Neural Networks (DN ...

2019

Actor neural networks for the robust control of partially measured nonlinear systems showcased for image propagation through diffuse media

Demetri Psaltis, Christophe Moser, Damien Claude-Marie Loterie, Eirini Kakkava, Babak Rahmani, Ugur Tegin, Navid Borhani

The output of physical systems, such as the scrambled pattern formed by shining the spot of a laser pointer through fog, is often easily accessible by direct measurements. However, selection of the input of such a system to obtain a desired output is diffi ...

SPRINGERNATURE2020

Tunable polarization converter based on one-dimensional graphene metasurfaces

Babak Rahmani

We introduce a new metasurface structure for controlling the polarization of light by leveraging a well-harmonized combination of graphene and dielectric. The proposed metasurface is composed of an array of rectangular pillars laterally sandwiched by ribbo ...

OPTICAL SOC AMER2018

Deep Learning-Based Image Classification through a Multimode Fiber in the Presence of Wavelength Drift

Demetri Psaltis, Christophe Moser, Navid Borhani, Eirini Kakkava, Babak Rahmani, Ugur Tegin

Deep neural networks (DNNs) are employed to recover information after its propagation through a multimode fiber (MMF) in the presence of wavelength drift. The intensity distribution of the speckle patterns generated at the output of an MMF when an input wa ...

2020

Learning to See and Compute through Multimode Fibers

Demetri Psaltis, Christophe Moser, Damien Claude-Marie Loterie, Eirini Kakkava, Babak Rahmani, Ugur Tegin, Ilker Oguz, Navid Borhani, Mustafa Yildirim

We propose a computational method for controlling the output of a multimode fiber using machine learning. Arbitrary images can be projected with amplitude-only calibration (no phase measurement) and fidelities on par with conventional full-measurement meth ...

IEEE2021

Backpropagation-free training of deep physical neural networks

Romain Christophe Rémy Fleury, Babak Rahmani, Ali Momeni, Matthieu Francis Malléjac

Recent successes in deep learning for vision and natural language processing are attributed to larger models but come with energy consumption and scalability issues. Current training of digital deep-learning models primarily relies on backpropagation that ...

American Association for the Advancement of Science2023

Roadmap on wavefront shaping and deep imaging in complex media

Demetri Psaltis, Christophe Moser, Babak Rahmani

The last decade has seen the development of a wide set of tools, such as wavefront shaping, computational or fundamental methods, that allow us to understand and control light propagation in a complex medium, such as biological tissues or multimode fibers. ...

IOP Publishing Ltd2022

Dispersion-Managed Soliton Multimode Fiber Laser

Demetri Psaltis, Christophe Moser, Eirini Kakkava, Babak Rahmani, Ugur Tegin

We demonstrate, to the best of our knowledge, the first spatiotemporally mode-locked dispersion-managed fiber laser. The fiber oscillator, which includes a 250 modes multimode fiber section, generates 20 nJ pulses centered at 1034 nm with 730 mW average po ...

IEEE2020

Controlling spatiotemporal nonlinearities in multimode fibers with deep neural networks

Demetri Psaltis, Christophe Moser, Eirini Kakkava, Babak Rahmani, Ugur Tegin, Navid Borhani

Spatiotemporal nonlinear interactions in multimode fibers are of interest for beam shaping and frequency conversion by exploiting the nonlinear interaction of different pump modes from quasi-continuous wave to ultrashort pulses centered around visible to i ...

2020

Multimode optical fiber transmission with a deep learning network

Demetri Psaltis, Christophe Moser, Damien Claude-Marie Loterie, Babak Rahmani, Georgia Konstantinou

Multimode fibers (MMFs) are an example of a highly scattering medium, which scramble the coherent light propagating within them to produce seemingly random patterns. Thus, for applications such as imaging and image projection through an MMF, careful measur ...

CHINESE ACAD SCIENCES, CHANGCHUN INST OPTICS FINE MECHANICS AND PHYSICS2018

All-fiber spatiotemporally mode-locked laser with multimode fiber-based filtering

Demetri Psaltis, Christophe Moser, Eirini Kakkava, Babak Rahmani, Ugur Tegin

We demonstrate the first all-fiber multimode spatiotemporally mode-locked laser. The oscillator generates dissipative soliton pulses at 1036 nm with 12 mW average power, 6.24 ps duration, and 24.3 MHz repetition rate. The reported pulse energy (0.5 nJ) rep ...

2020

Deep learning assisted image transmission in multimode fibers

Demetri Psaltis, Christophe Moser, Damien Claude-Marie Loterie, Babak Rahmani, Georgia Konstantinou

We propose a data -driven approach for light transmission control inside multimode fibers (MMFs). Specifically, we show that a convolutional neural network is able to reconstruct amplitude/phase modulated images from scrambled amplitude -only images obtain ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Transmission in Multimode fiber with deep learning

Demetri Psaltis, Christophe Moser, Damien Claude-Marie Loterie, Babak Rahmani, Georgia Konstantinou

Spatio-temporal control of femtosecond pulse-delivery through multimode fibers (MMF) can be used to achieve two photon photo-polymerization. Transmission-matrix method is used in linear domain to solve the scrambling effect at the fiber output and generate ...

IEEE2018

System and method for projecting images through scattering media

Demetri Psaltis, Christophe Moser, Babak Rahmani

The invention discloses a system (1) and method to guide light through a scattering medium (4) and project images on a screen (5) placed after the medium (4). Many of the shortcomings of previous approaches for guiding light through scattering medium (4) h ...

2020

Spatiotemporal self-similar fiber laser

Demetri Psaltis, Christophe Moser, Eirini Kakkava, Babak Rahmani, Ugur Tegin

Spatiotemporal mode-locked fiber lasers are a type of ultrafast lasers for which the longitudinal and transverse modes of the multimode fiber cavities are locked via nonlinear interaction in the cavity. Here we report the experimental realization of a spat ...

2019

An actor-model framework for visual sensory encoding

Demetri Psaltis, Christophe Moser, Diego Ghezzi, Babak Rahmani, Franklin Leong

A fundamental challenge in neuroengineering is determining a proper artificial input to a sensory system that yields the desired perception. In neuroprosthetics, this process is known as artificial sensory encoding, and it holds a crucial role in prostheti ...

Nature Portfolio2024

Spatial self-beam cleaning in spatiotemporally mode-locked fiber lasers

Demetri Psaltis, Christophe Moser, Eirini Kakkava, Babak Rahmani, Ugur Tegin

IEEE2021