Auf Wiedersehen IPHT!


The 28th of April was my last official day at the Leibniz Institute for Photonic Technology (IPHT). I consider myself very lucky to have been a part of this incredible group (shown nostalgically in the black-and-white photograph above) led by Prof. Markus A. Schmidt, covering numerous and diverse fields such as plasmonics, non-linear optics, hybrid photonics, metasurfaces and metamaterials, bio-photonics and sensing (and more!) – all within the optical fiber platform. I thank the Alexander von Humboldt Foundation, which sponsored my fellowship and made me feel at home in Germany from the get-go.

I had a very productive and fun two and a half years, making many friends and connections not only inside IPHT, but also in the neighboring Abbe Center of Photonics and the Fraunhofer Institute, as well as the Max Planck Institutes and Center for Molecular Biomedicine – what an environment! Anyone who visits Jena is immediately impressed by the quality of the infrastructure within the City of Light – and I mean that in terms of human, scientific, and educational resources. Of particular note is the Masters in Photonics Program at the Abbe School of Photonics (at which I had the pleasure of lecturing, overseeing student seminars, and superviseing Masters students), which I believe currently provides the best-value English-language photonics education in the world.

Looking back at my two years at IPHT, I produced four first-author publications (with a few more on the way!), contributing four more as co-author, while still contributing to papers with colleagues in Sydney and Freiburg. Fortunately, the experience gained by the group through my contributions has not been lost, and I am confident that the students I recruited and trained will continue with great success in the years to come!

I’ll be officially starting on June 1st at the Australian Institute for Nanoscale Science and Technology, under the University of Sydney Fellowship scheme working on hybrid nonlinear plasmonics with Stefano Palomba and Martijn de Sterke. They’ve been coming up with breakthrough developments and I’m very keen to get started. I learned a lot over the past two years at IPHT, giving me numerous ideas that I intend to pursue in my next position – and beyond.

Thank you IPHT and everyone in Jena – this is my Auf Wiedersehen. I’ll be in touch!

Paper published in the Optical Materials Express Multimaterial and Multifunctional Optical Fibers Feature Issue


Our new paper “Analysis of nanogap-induced spectral blue-shifts of plasmons on fiber-integrated gold, silver and copper nanowires” just appeared in the Optical Materials Express feature issue for “Multimaterial and Multifunctional Optical Fibers”!

Ron Fatobene Ando did a fantastic job in performing a systematic analysis of the origin nano-gaps between the metal and the silica fiber wall, which emerge when filling the nanochannels in photonic crystal fibers and modified step-index fibers with metals. This study was performed for the two canonical plasmonic metals, silver and gold, as well as for copper. By measuring the plasmonic resonances and comparing with simulations, we can obtain an accurate estimate of the nanogap sizes, finding that  they are much smaller than one might expect – we think this effect is due to the interaction of van der Waals and contraction forces at the material interfaces. This will be particularly important for many of the future fiber-plasmonics devices we are designing.

In other news, paper “Excitation of Short-Range Surface-Plasmon Polaritons in a  Gold Nanowire Enhanced Step-Index Fiber” has been accepted as an oral contribution for CLEO Europe, which will be held during the World of Photonics Congress 2017 in the International Congress Centre (ICM Munich, Germany). It will be presented June 27, 2017 at 8.45 in the Mode control session, ROOM 13b.


Back from the CUDOS workshop!


Photo by Alvaro Casas Bedoya

Just returned from a week in Australia, where I had the pleasure of attending the 16th (and final!) CUDOS workshop. This was an opportunity to participate in four days of discussion in a variety of forums such as keynote addresses, research presentations, poster displays and social events from several distinguished speakers – highlights included a keynote talk from Katherine Woodthorpe, and invited talks from Shanhui Fan, Kobus Kuipers, John Sipe and  Alex Szameit, to mention a few. I presented a poster (see below) on our recent work , and met with my future colleagues at the University of Sydney Stefano Palomba, Martijn de Sterke and Guangyuan Li. The laser-tag skirmish event in the Australian bush during the record-setting heat-wave sun was as brutal an affair as one might imagine. The closing gala dinner delivered some emtional moments, as we all reflected on what made CUDOS so succesful, and the legacy it will leave: a combination of synergistic national and international collaborations, the ability to foster researchers both academically and into developing industrial partnerships and start-ups, student outreach, and contirbuting to overall excellence in photonics on a global scale, have created a truly unique research environment which will continue even after CUDOS ends, and which will serve as a model for research centers everywhere.


Excitation of propagating short-range surface plasmons in a nanowire-enhanced step index fiber – Nano Letters


Our paper “Hybrid-Mode-Assisted Long-Distance Excitation of Short-Range Surface Plasmons in a Nanotip-Enhanced Step-Index Fiber” was published today. We propose a means of exciting short-range surface plasmon polaritons at the endface of a step-index fiber which contains a gold nanowire in its core. The radially polarized hybrid dielectric mode of the gold-filled section has low loss, with some field on the nanowire surface – so that after the light reaches the fiber endface, the energy propagates along the tip to nanoscale apex via the short-range plasmonic mode. We fabricated the structure and looked in detail at the properties of the scattered/transmitted light for different input polarizations. We found that the light scattered from the tip is most intense when the input is radially polarized, and that this light is polarized along the direction of the fiber axis, confirming the feasibility of this excitation scheme. This is a route to improving the capabilities of deeply-subwavelength near-field probes in a convenient fiber platform.

Back from FIO!

Had a great week at the Frontiers in Optics conference in Rochester, presenting our recent experimental work integrating gold nanotips in a step index fiber. Conferences are always inspiring, but this was a particularly special event, marking the 100 years of the Optical Society of America. Several Nobel prize speakers participated in a fascinating panel discussion following Michio Kaku‘s talk on speculations regarding the next 100 years. The conference dinner party was spectacular! (See if you can spot me dancing.)  It was also great to catch up on with old friends, and make some new ones. Towards the end I also had the chance to drive up to Toronto and visit Peter Herman’s group – I gave a talk on fiber plasmonics, and we discussed a collaboration. What a week!

DoK’s4DoK’s @ DoKDoK


Last Wednesday I had the pleasure of being an invited speaker at DoKDoK, the 5th Student-organized conference on Optics, held each year at Oppurg Castle, close to Jena. I participated in a panel discussion in the context of Dok’s4Dok’s, to present my experiences and views on publishing in high impact and/or low(er) impact journals. Some of the questions raised included:

What are benefits and drawbacks of publishing in either type of journal? Which one is more worthwhile in terms of science? Which is more important in terms of increasing the likelihood of a successful academic career?

Panel member Silvio Fuchs had different opinions in some circumstances, and many of the Masters and PhD students were very keen to find out more, asking us several questions throughout. It was a sitmulating hour of discussion, and I had the chance to consolidate some of my own opinions on this topic in the process.

For an introduction to the subject, this comic by PhDComics is a good place to start!

Progress in metamaterial cladding hollow core fibers


Several papers on metamaterial-cladding hollow core fibers have come out just in the past couple of weeks. We had our very own Optics Express paper presenting an analytic model for calculating the dispersions (including losses) of large-area hollow core fibers with complex claddings, for an example metamaterial cladding (formed by sub-wavelength metal wires) at 3μm and 10.6μm. This work continues our previous work on such structures, and can be applied to a large variety of geometries.This opens up many new design opportunities, and a simple method for performing otherwise very intensive calculations.

M. Zeisberger, A. Tuniz and M. A. Schmidt, “Analytic model for the complex effective index dispersion of metamaterial-cladding large-area hollow core fibers”, Optics Express 24, 20515-20528 (2016).

At the same time, the metamaterial fibers group in Sydney have shown two back-to back publications showing the theory and experiment of a single-mode, single-polarization hollow-core THz fiber with a metamaterial cladding, consisting of subwavelength-diameter metal wires embedded in a dielectric host, a promising platform for compact and low-loss terahertz waveguides.

Great to see this progress in the field!

Removing image artefacts in wire array metamaterials


The new paper by Samiul Habib et al. from the Sydney metamaterial fibers group presents a comprehensive overview of how to remove imaging artefacts when using wire media for sub-wavelength imaging. This is particularly important for using these hyperlenses as broadband subwavelength imaging devices. Three methods are presented based on convolution, field averaging, and power averaging. A technique relying on a projection in spatial Fourier space to filter out all ordinary waves overcomes the distortions we observed in our Scientific Reports paper from last year when imaging large objects with sub-wavelength features. The images above were obtained using my Python code – contact me if you might be interested in using it!

Md. S. Habib, A. Tuniz, K. J. Kaltenecker, Q. Chateiller, I. Perrin, S. Atakaramians, S. C. Fleming, A. Argyros, and B. T. Kuhlmey, “Removing image artefacts in wire array metamaterials”, Optics Express 24, 17989-18002 (2016).