(Me, circa 2008😅)

Alexandros Pitilakis

Hi! Thanks for visiting my personal website

I'm a postdoc doing research and, until recently, teaching/lecturing. My background is in electrical and computer engineering, with a specialization in telecommunications, and an expertise in high-frequency electromagnetic waves and light-matter interaction.

Here's some of my profiles on various platforms.

Don't hesitate to contact me through these or at alexpiti@auth.gr

For News, Research, Résumé, etc., check the collapsible groups below.

News

2024, April: I presented a talk at PIERS 2024 Chengdu on the "Analysis and Design of Vector Holographic Metasurfaces". Full-length paper to appear in IEEE Xplore...
2023, July: We published a paper in IEEE Access titled "On the Mobility Effect in UAV-Mounted Absorbing Metasurfaces: A Theoretical and Experimental Study". Check out it here (DOI), it's open-access! This was an interesting study blending measurements and physical optics. [PDF@IEEE Xplore]
2023, July: I was in Paris for META 2023, and gave a talk (invited) on holographic metasurfaces and presented a poster on graphene-enabled Kerr microcombs. Send me an email if any of the two sounds interesting.
2023, May: I gave a lecture at second year ECE students of University of Western Macedonia, on electromagnetic metasurfaces and their applications in wireless communications. You can find the video [here] and a PDF of my slides [here]; both in Greek! :)
2022, September: My paper titled "Ultrafast pulse propagation in graphene-comprising nanophotonic waveguides considering nonperturbative electrodynamic nonlinearity" has been published in JOSAB. [Optica Publishing Group / DOI] [Full Text (Preprint) & Supplement]
2022, July: Check out my recent talk on "Integrating Software-Defined Metasurfaces into Wireless Communication Systems:Design and Prototype Evaluation" presented at the 27th IEEE Symposium on Computers and Communications (ISCC 2022). [Video Recording]
2022, July: Our paper titled "Multi-functional metasurface architecture for amplitude, polarization and wavefront control" has been published in Physical Review Applied and got the Editors' Suggestion! [APS Journals / DOI] [arXiv] [Supplemental Material]
2022, June: My [GitHub] is finally up and running :-) I've added four repositories so far: two for antennas & metasurfaces, one for integrated optics & waveguides, and one for paraxial ray-optics. I hope more will come soon.
2022, March: First version of my paper, titled "Graphene optical nonlinearity: From the third-order to the non-perturbative electrodynamic regime", is up on [arXiv]. Piecing this together was a long-time effort. Feel free to contact me and discuss!

Research and Interests

My prime field of expertise is electromagnetics, theoretical and computational; specifically guided and radiated waves. My current research is focused in two (distinct) areas: graphene-enhanced nonlinear photonic devices and reconfigurable microwave metasurfaces. Here's a few of my latest published works:

For a full list of my publications, you can always check my Google Scholar profile.

My broader interests include silicon photonics, plasmonics, electro-optical phenomena, 2D material physics, metamaterials, liquid crystals, microstructured fibers, classical optics, optical fiber communications, mmWave & THz technology, antennas & propagation. Sounds a lot? Well, a researcher cannot always choose what to work on, and there's always an opportunity to learn new things :)

I have laboratory experience with optical fiber systems, free-space optics, antenna and RF/microwave technology & associated measurements.

Brief Résumé

I was born in Thessaloniki, in 1982, and got my 5-years MSc diploma in Electrical and Computer Engineering (ECE) with a specialization in Telecommunications in 2005, from the engineering faculty of the Aristotle University of Thessaloniki (AUTH). I hold another MSc degree, awarded from ENST/Telecom Paris in 2007, including a 6-month internship at Alcatel-Lucent (now Nokia Bell Labs) optical transmission group, where I worked on dispersion managed heterogeneous optical fiber networks.

After my military service at the Hellenic Navy, I resumed research, now focused on integrated photonics, supervised by professor Emmanouil Kriezis (AUTH-ECE Photonics group) leading to a PhD granted in 2014 from ECE/AUTH. My doctorate thesis title is "Analysis, design and characterization of integrated photonic devices based on the hybrid conductor-dielectric-silicon technology" and you can find it here (in Greek, but you can still figure out the math and the figures!).

Since 2014, I've been working as a postdoctoral researcher affiliated with AUTH, FORTH (IESL and ICS), NHRF, and UoWM. I have been involved in a number of grants, scholarships and research projects, both national and European. Throughout these years, I've been extensively collaborating with Dr. Odysseas Tsilipakos and Profs. Emmanouil Kriezis, Nikolaos Kantartzis, Christos Liaskos, Maria Kafesaki, and Alexandros-Apostolos Boulogeorgos.

Apart from R&D, I've served as an adjunct lecturer at ECE-AUTH (2016-2018) and also at ECE-UoWM (2016-2023), fully in charge of teaching senior year undergraduate courses: photonics, optics, and antennas & propagation.

Computational Electromagnetics

Throughout my involvement with research, from 2004 to this day, I've developed scientific software and simulation tools primarily in MATLAB. It's something that I enjoy and also find useful; when both happen in the same project, so much the better! So, my main tools are various 1D and 2D full-vector mode-solvers and beam-propagation methods (BPM), implemented with analytical formulas (where possible, e.g., when a characteristic equation can be formulated) or finite difference/element methods (FDM/FEM), for complicated geometries. It's surprising how many things one can do with only these tools! Other, minor projects include coupled spatiotemporal ODEs (e.g. multi-pulse propagation in nonlinear waveguides coupled with carrier effects), ray/geometrical optics, and FDTD.

I'm presently setting up my [GitHub] page, to share these codes, as most of them can be handy tools for engineers in optics and photonics. Some of them are educational, but can easily be converted into R&D tools. Here's a list of what I've developed, with the ones already on GitHub marked in blue. If something from the list below interests you, don't hesitate to contact me. Maybe we can collaborate, on development and/or in applications.

Electromagnetics:

[2D solver] --> Finite-element anisotropic vectorial eigenmode solver (I call it FEAVES for short), with post-processing and visualization. This is my main "workhorse". Supports bulk and sheet (graphene-like) anisotropic lossy materials. Meant for arbitrary planar/integrated waveguides and photonic-crystal fibers, but it can handle any type of waveguide, including RF/microwave transmission lines. I have developed a lot of post-processing for the extraction of effective waveguide parameters, e.g., GVD and nonlinear parameter "gamma" used in coupled nonlinear multi-channel/mode pulse propagation (NLSE framework).
[2.5D solver] --> Finite-element BPM (fed by the solver), including pre-processing & visualization of geometry and fields. This is my secondary "workhorse" and is fully compatible with FEAVES, i.e., it supports arbitrary (incl. transverse-longitudinal) anisotropy in bulk/3D and sheet/2D (graphene-like) material properties. This BPM uses a higher-order Padé-approximation to minimize diffraction error. It was developed for integrated longitudinal/paraxial structures such as directional couplers, tapers, Y-junctions, MZI, MMI, AWG. But, apart from integrated waveguide devices, it can obviously handle any type of low-reflection propagation media, e.g., laser beams (Gaussian, vortex) in nonlinear gases, spot formation etc.
[2.5D solver] --> Finite-difference BPM, with full-vector, semi-TE/TM and scalar variants. Less developed than my FE-BPM, which is more useful in most cases.
[1D solvers] --> Slab waveguide solver, for one or arbitrarily many slabs. TE & TM modes. Can handle lossy and/or plasmonic materials too. Based on a "smart solution" of the characteristic equation.
[1D solvers] --> Arbitrary complex-valued index profiles. TE modes only. Based on FD-modelling of the cross-section.
[1D solvers] --> Step-index single-core fibers. Vector/hybrid (HE modes) and scalar formulation (LP modes). Supports plasmonic "tubes" (e.g. graphene-clad microfibers in THz). Based on characteristic equation solution.
[1.5D solver] --> FD-BPM (with feeding from above mentioned 1D solver), including pre-processing & visualization of geometry and fields.

Optics:

[Matrix methods] --> Paraxial methods for transmissive (and unfolded-reflective) optical systems w/ multiple apertures and stops. Used for estimation of entrance/exit pupils and all cardinal points.
[Ray Tracing] --> 2D ray-tracing, both sequential (e.g. for lens analysis) and arbitrary (e.g., for free-space optics), with visualization & post-processing, e.g., for calculation of wavefront shape, F-number etc.. Supports aspheric (and some free-form) optical surfaces, while ray-polarization/amplitude tracking (via Fresnel coefficients) and diffractive surfaces implementation are underway.
[Ray Tracing] --> 3D sequential ray-tracing for accurate lens design, with visualization & post-processing (e.g. spot-diagrams).
[Aberrations] --> Analytical object-image formation, on a pixel-sensor
[Scattering] --> Huygens-Fresnel scattering-pattern approximation (at farfield/Fraunhofer region) for reflect-arrays and metasurfaces, using physical optics concepts.

I'm also experienced in several commercial computer-aided engineering tools (CST, HFSS, COMSOL, FlexPDE), and their scripting/interfacing with more research-friendly environments (MATLAB!).