Pulse modulation by Bloch surface wave excitation

Significance 

Planar dielectric multilayers are known to possess resonant properties, which play a critical role in guiding and sustaining different kinds of optical modes. This is well corroborated in the literature. Among the existing electromagnetic surface modes, Bloch surface waves (BSWs) have drawn considerable interest owing to the advantages of the energy and momentum narrow resonances. The narrow resonances together with the evanescent field distributions, facilitate the interaction between the BSWs and the external medium.

Although a considerable amount of research on BSW excitation has been reported, most of them have mainly focused on momentum, spectral and spatial features associated with the coupling and manipulation of BSWs. However, the possible temporal effects have been substantially neglected despite its important implications in practical applications, especially those involving the use of BSW excitation to trigger ultrafast light-matter interactions. The temporal and spectral properties of pulses can be significantly modified in the presence of photonic bandgaps and resonances, resulting in temporal widening, splitting and tailing effects. Moreover, different deposition techniques enable the selection of suitable materials for fabricating multilayers sustaining BSWs across a broad spectral range.

On this account, researchers at the University of Eastern Finland: PhD candidate Atsu Asilevi, Dr. Henri Pesonen, Dr. Ségoléne Pelisset, Professor Matthieu Roussey and Professor Jari Turunen together with Professor Emiliano Descrovi from Polytechnic University of Turin studied the effects of BSW excitation on temporal characteristics of short optical pulses. The structure considered in this study was a dielectric multilayer consisting of N identical low-/high-index bilayers with an extra terminating layer separating the substrate and the superstrate. The BSW resonance and the spectral width of the incident pulse were assumed to be of the same order of magnitude. Their work is currently published in the journal, Optics Letters.

The research team showed that a sharp spectral phase variation around the BSW resonance resulted in a profound temporal modulation of the reflected pulse. The occurrence of such resonant excitation within the spectrum of the incident pulse resulted in the temporal splitting of the reflected pulse into leading and trailing parts, with the trailing part exhibiting an exponentially decaying tail. The role and importance of the number of bilayers and the absorption level in the multilayer stack were discussed. The observed temporal splitting effect could be implemented in BSW-based sensing platforms employing time-gated detection to filter out undesired backgrounds and improve the collection of useful signals. Furthermore, it was worth noting that, unlike incident pulses, the spectral width of the BSW resonance had a significant effect on the characteristics of the temporal modulation.

In summary, the authors reported a theoretical analysis of pulse modulation by BSW excitation as well as the effects of BSW resonances on the temporal properties of evanescent-wave pulses. Although the discussion was restricted to a plane-wave pulsed excitation, the analysis could be extended to finite-size confined pulses. This provided more insights into the temporal and spectral behaviors of the pulses inside and on top of the multilayer structure. In a statement to Advances in Engineering, first author, Atsu Asilevi pointed out their study contributes to advancement in the application of BSW excitation in pulse modulation.

Pulse modulation by Bloch surface wave excitation - Advances in Engineering
Fig. 1 (a) Device geometry. (b) Frequency domain response of the device showing the normalized incident., reflected and transmitted spectral density. (a). (c) The temporal intensity profile Ir(0, 0; t) of the reflected pulse as a function of the spectral detuning parameter δω. (d). Intensity profiles at specific values of δω. Black: δω0 = 0. Blue: δω1 = 0.00375 rad/fs. Red: δω2 = 0.00815 rad/fs. Green:δω3 = 0.0119 rad/fs.

About the author

Atsu L. Asilevi received his Bachelor of Science Education from the University of Education Winneba Ghana, in 2014. He then obtained a scholarship to pursue a master’s degree in Photonics Engineering at the University of Eastern Finland (formally University of Joensuu) in 2015 and graduated in 2017. He is currently pursuing his PhD in the same university in the department Physics and Mathematics, Center for Photonics Sciences (formally Institute of Photonics). His PhD study focuses on the theoretical and computational modelling of electromagnetic surface waves in the spatio-temporal domain. He combines the theories of diffractive optics (diffraction and diffraction gratings), polarization, coherence to reveal new properties about these electromagnetic surface waves for tomorrow’s applications.

About the author

Emiliano Descrovi is Associate Professor in Physics at the Department of Applied Science and Technology (DISAT), Politecnico di Torino, Italy. He obtained his master degree in Physics from the University of Torino in 1999 and the PhD in Microtechnique from the Université de Neuchatel, Switzerland, in 2005.

His research interests falls in the domain of nanophotonics and light-responsive polymer photonics, targeting novel tunable devices controlled by light. In this framework, significant efforts are aimed at gathering new knowledge about the integration of individual sources within all-dielectric multilayered nanostructures and the related active manipulation on the emitted radiation coupled thereto.

About the author

Henri has studied nonlinear material interactions with pulsed, partially coherent and polarized light fields as well as effects of widelly-used optical elements on partially coherent light. He is also experienced in modelling behaviour of electromagnetic fields. Currently Henri is working in Dispelix.

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About the author

Jari Turunen (born 1961) received his D. Sc. degree from Helsinki University of Technology in 1990, with a thesis entitled “Variable-coherence beam optics”. He then moved to Heriot-Watt University in Edinburgh for a three-year post-doctoral period, working mainly on optical interconnects based on diffractive optics. In 1994-1999 he was Professor of Optoelectronics and thereafter Professor of Physics at the University of Joensuu (now University of Eastern Finland, UEF). In 2005-2010 he was an Academy Professor (Academy of Finland). His research and teaching cover fundamental and applied aspects in coherence and polarization optics, diffraction and gratings, optical design, nanophotonics and metamaterials, waveguides and plasmonics, and ultrafast optics. He has published over 320 peer-reviewed papers and supervised more than 35 Ph.D. theses.

About the author

Matthieu Roussey is professor of experimental photonics at the Department of Physics and Mathematics of the University of Eastern Finland. He obtained his PhD from the University of Franche-Comté (France) in 2008 and was postdoctoral researcher/group leader at Ecole Polytechnique Fédérale de Lausanne (Switzerland) from 2007 to 2011.

His research is focused on integrated optics with an interest in combining micro and nanostructure with different waveguide types made of different materials to enhance physical phenomena, determine new building blocks, ease the fabrication, and increase light/matter interactions. The main applications of his research are in environmental monitoring, atmospheric sensing, and microplastic detection in water.

About the author

Ségolène Pélisset is a Diploma-engineer in Materials Science (ECPM, Strasbourg, France) and has completed her PhD in Photonics at the University of Eastern Finland (Joensuu, Finland). She is now Manufacturing Engineer in Dispelix Oy (Joensuu, FInland).

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Reference

Asilevi, A. L., Pesonen, H., Pelisset, S., Descrovi, E., Roussey, M., & Turunen, J. (2022). Pulse modulation by Bloch Surface Wave Excitation. Optics Letters, 47(10), 2574-2577.

Go To Optics Letters

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