Author: Mikolaj K. Schmidt

Our struggles with designing new optoacoustic waveguides continue! Our draft, previously published here arxiv:1909.01632, is now published in New Journal of Physics as an open-access publication (click here for the pdf). 

After developing a blueprint for suspended mid-IR waveguide for forward Brillouin scattering, we look to we introduce a new type of optoacoustic waveguides, dubbed ARRAWs (Anti‑Resonant Reflecting Acoustic Waveguides), which implement acoustic guidance in multi-layer waveguides planar and cylindrical by engineering anti-reflective cladding layers that suppress the dissipation of acoustic waves.

This principle was previously embraced in the optical domain and led to the development of the Anti-Resonant Reflecting Optical Waveguides (ARROWs), which are now widely used in biomedical photonic devices.

This work is prepared in collaboration with Matthew O’Brien – brilliant student once at MQ, now at UNSW, Mike Steel at MQ and Chris Poulton at UTS.

An important development on the front of Molecular Optomechanics (MO)!

The initial proposals for MO coming from the groups of Kippenberg and Galland and Aizpurua were introduced to describe off-resonant Raman scattering from molecules in plasmonic cavities. The keyword here is off-resonant, meaning that these formalisms did not consider the effect of populating excited electronic levels. The natural extension of this formalism towards resonant Raman scattering (RRS) has now been put forward in the paper entitled “Quantum description of surface-enhanced resonant Raman scattering within a hybrid-optomechanical model” published in Physical Review A.

This work was led by the former PhD student from the group in San Sebastian, now a postdoc at Harvard – Tomas Neuman, and co-authored by Ikerbasque researchers Geza Giedke and Ruben Esteban, Theory of Nanophotonics Group leader Javier Aizpurua and me.

Our manuscript on novel design of mid-IR silicon waveguides for Brillouin scattering was just published in Optics Express (open access)! In this work we merge ideas from linear physics of mid-IR waveguides developed in the research groups of our co-authors – Profs. Goran Mashanovich and Graham Reed from The University of Southampton (click here for one of their reports), with the some phonon bandgap engineering to design novel waveguides operating in mid-IR (which is hard and attractive!), and exhibiting strong SBS gain.

I’m off to visit Southampton in a month, to figure out where to take this work next!

Good news!

I was awarded competitive (as hell!) Macquarie University Research Fellowship (MQRF), to continue my work at MQ for the next 3 years! The project I submitted, together with Prof. Michael J. Steel, is focused on developing optoacoustic nanosystems for QAD – quantum acoustodynamics.

More results (hopefully) soon!

In collaboration with Luke Helt, Chris Poulton and Michael Steel we have recently submitted our new manuscript on the elastic analogue of the electromagnetic Purcell factor for review. It has been finally published in Physical Review Letters, and highlighted as an Editors’ Suggestion. You can either read it on the PRL website, or access the arXiv version for free.

In this manuscript we explore a possible analogue of the familiar electromagnetic concept – modification of the energy dissipation rate from a localized, dipolar source. In our study, the source in given by a localized harmonic force, and the modification of its radiation is governed by an elastic nanoantenna – a small spherical particle positioned near the emitter, and embedded in a different elastic material. We provide a theoretical framework for identifying the quasi-normal modes of the structure, demonstrate the effects in an exemplary system, and discuss the possibility of using this effect for engineering the rates of nonlinear, phonon-mediated optical effects.

Our paper Pulsed Molecular Optomechanics in Plasmonic Nanocavities: From Nonlinear Vibrational Instabilities to Bond-Breaking has just been published in Physical Review X (Open Access)!

It’s a part of our effort to verify the predictions of the optomechanical picture of Raman Scattering from molecules, which was first proposed by researchers from EPFL, and further developed in my former group, headed by Javier Aizpurua in San Sebastian in Basque Country, in collaboration with Geza Giedke and Alejandro Gonzalez-Tudela.

The paper reports and discusses nonlinearities observed in Raman scattering from molecules positioned in well-controlled plasmonic nanosystems, which have been extensively studied by the research groups of Jeremy Baumberg at Cambridge University. While these systems are rather easy to destroy by a strong continuous laser illumination, Anna Lombardi, the lead author of the paper, found that one can instead use picosecond pulses of a much more intense laser source to stimulate the vibrations of the molecules.

Furthermore, she observed that the amount of light scattered off the molecules in the Raman process does not scale linearly with the peak intensity of the lasers! Instead, in accordance with the predictions of the Molecular Optomechanical, the Raman scattering becomes superlinear after a certain threshold.

Our manuscript “Spectral Selectivity of Plasmonic Interactions between Individual Up-Converting Nanocrystals and Spherical Gold Nanoparticles”, describing experimental and theoretical analysis of the effect of plasmonic nanoparticles on two independent relaxation channels of nanocrystals, has been published in MPDI Materials. The experiments were conducted in Optics of Hybrid Nanostructures labs at Nicolaus Copernicus University in Torun, Poland.

Fellow quantum-nano-people! I’ve had a pleasure to contribute to the organization of the Nanoscale Quantum Optics conference/workshop, which will take place in Budapest in late October 2017.
It’s an Early Career Researchers only event, so there will be few PIs dominating the discussions, and hopefully many opportunities to grab a beer (or palinka) with your peers!

Over the last few months, we (me in collaboration with my former group in San Sebastian and Jeremy Baumberg’s group at Cambridge University) have been preparing a contribution for the SERS: Faraday Discussion – a conference organized by the Faraday Division. Its format is unique, as the invited speakers prepare manuscripts a few months in advance, share them among attendees who then have a few months to prepare for a lively and lengthy discussion at the conference.  Thus, it’s a perfect venue to hash out the nitty-gritty details of new formalisms or ideas.

We have prepared manuscript entitled Linking classical and molecular optomechanics descriptions of SERS in which, as the title suggests, we attempt to close the gap between the classical formalisms used by the SERS community, and molecular optomechanics introduced by the LQNO group from EPFL and the expanded by us. We compare the two optomechanical formalisms to each other and to experiments, and then show how they can be simplified to the classical framework. We also develop and present classical intuitions to the phenomena leading to non-linearities in Raman scattering, and discuss some (much earlier!) contributions where they’ve been partially predicted.

On January 30, I started my two-year contract at Macquarie University in Sydney, Australia, in the group of Michael Steel, collaboration with researchers from UTS (University of Technology Sydney) led by Christopher Poulton and from University of Sydney (group of Ben Eggleton).

The exact focus of my project isn’t well defined yet, as we are trying to work out where our research interests and goals overlap. Nevertheless, it seems like I will attempt to apply my (limited) experience in cavity optomechanics to look into the newly developed quantum-mechanical description of SBS – Stimulated Brillouin Scattering in dielectric waveguides. I will soon update the project website and include links to the relevant papers.

I will also be working on applying the classical framework and solving real-life problems (sic!) with the software developed by researchers from UTS and USydney – NumBAT.

Pictures, photos, papers (hopefully!) and blog entries will come soon!

During my stay at Warsaw University I was invited by my host – Prof. Konrad Banaszek (who, BTW is moving to Center of New Technologies and starting a new project Quantum Optical Communication Systems) to give a seminar on the quantum-mechanical elements of my PhD work. Afterwards, I have had the pleasure to give another seminar (invited by Dr. Karolina Slowik who recently moved back to Torun and brought her expertise on the plasmon/quantum optics interface and starting project

High enhancement and Interference of Molecular Transitions) on molecular optomechanics at my alma mater – Nicolaus Copernicus University in Torun.

I will post the (better) second presentation here soon – unfortunately, there are still things we haven’t published in there yet.

Also, I’m about to visit Alejandro González-Tudela at the Max-Planck Institute for Quantum Optics in Garching near Munich, Germany from (17-20 Jan. 2017). We plan to finish a paper on frequency-resolved two-photon correlations in generic optomechanical systems. Fingers crossed!