Towards reconfigurable digital complex photonic systems

Hasan Yılmaz

MSN Graduate Program and UNAM

Optical waves scattered or emitted by materials carry information in temporal (spectral) or spatial domains. Perhaps, the most prominent example of optical information is an optical image that is created by an optical microscope. With the emergence of information technology, optical information can be digitized and computationally processed. Computational optical imaging systems typically map spatial and spectral information of light waves to the spatial properties of materials. However, most optical materials are complex (three-dimensional and opaque): we cannot see inside or behind them. This is because opaque materials’ refractive index is inhomogeneously distributed in space. Incident light waves scatter into random directions upon propagation through opaque materials such as clouds, mil kor biological tissue, which scrambles the spatial information. Such a random light scattering process complicates the mapping between scattered light waves and three-dimensional structures.

In this talk, first I will introduce the transmission matrix concept which maps the incident light waves to the scattered light waves through complex optical materials. The main ingredient of this talk will be the ‘transmission-matrix-based operator’ approach. I will show that the transmission matrix not only enables us to transport optical information through a complex material (e.g. a layer of white paint or multimode fiber), but it also enables us to modify the relationship between certain incident waves, scattered waves, and the configuration of the system. Our ‘transmission-matrix-based operator’ approach provides a general framework for designing and creating a desired input-output relationship of classical and quantum light waves for various applications in imaging, metrology, and communication through complex materials.

Finally, I will introduce the inverse scattering problem in complex photonic systems such as multiple-scattering materials. Benefiting from the ‘transmission-matrix-based operator’ approach, I will briefly propose reconfigurable digital complex photonic systems. Such systems will not only be ideal hardware platforms to physically simulate inverse scattering problems but also lead to reconfigurable multimode photonic devices such as dynamic mode converters, mode demultiplexers, etc.

About Speaker

Hasan Yılmaz is currently an assistant professor at Bilkent University, the Institute of Materials Science and Nanotechnology. His research interests cover experimental and computational optics and photonics, light scattering, optical imaging and spectroscopy, computational imaging, wavefront shaping, spatiotemporal control of light, complex photonic materials, mesoscopic physics of light, statistical optics, laser physics and random matrix theory.

Previously, he worked as a postdoctoral associate and an associate research scientist at Prof. Hui Cao’s lab, Yale University, the Department of Applied Physics. He has received a Ph.D. degree from the University of Twente in the Netherlands for his thesis entitled “Advanced Optical Imaging with Scattering Lenses,” with Prof. Allard Mosk in 2015. Before this, he has received a M.Sc. degree in Materials Science and Engineering at Koç University, where he worked with Prof. Ali Serpengüzel at the Microphotonics Research Laboratory. He has a B.Sc. degree in Physics Engineering from İstanbul Technical University.

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