Hybrid Photonic-Plasmonic Devices with Single Nanoscale Light Sources Esteban Bermúdez Ureña ICFO- The Institute of Photonic Sciences Universitat Politècnica de Catalunya Castelldefels (Barcelona), July 2017 Thesis committee: Prof. Dr. Oliver Benson (Humboldt University Berlin, Germany) Prof. Dr. Anatoly Zayats (Kings College London, United Kingdom) Prof. Dr. Niek van Hulst (ICFO – The Institute of Photonic Sciences, Spain) Hybrid Photonic-Plasmonic Devices with Single Nanoscale Light Sources Esteban Bermúdez Ureña under the supervision of Prof. Dr. Romain Quidant submitted this thesis in partial fulfillment of the requirements for the degree of Doctor by the Universitat Politècnica de Catalunya Castelldefels (Barcelona), July 2017 To Dani, and my family. Acknowledgements The work and time spent during this thesis would not have been as successful and enjoyable without the help, support and presence of many people, both in and outside our institute. ICFO is a great place and every year grows stronger as a research institution. I wouldn´t be surprised if in ten year it extends all the way to the beach. High impact publications aside, without a doubt, the pillars of ICFO’s success are the people inside it, and I´m forever thankful to every member of ICFO´s community that made a positive impact, either on my work, or in my daily life over the past years. First of all, I would like to thank Romain for giving me the opportunity to join his group but most importantly for providing his continuous support and guidance throughout my PhD. I´m very grateful to have had everything I needed during my PhD and I also thank him for providing the right amount of scientific freedom to carry my own ideas and lead projects with our collaborators. I highly esteem having Romain as my mentor over these years, thank you for all the patience and support. Besides earning all the available grants, one of Romain´s achievements has been to select the right people to build a group with a great environment, my dear PNOs! Many have come and go during these years but I keep good memories of our times together. I was lucky to share my office with great people, starting from Giorgio and Srdjan, whom I also thank for their help and cleanroom training during my first stage of the PhD. Then came the second generation in the office with Ozlem and only Jose, it was always easy to have a laugh together. Finally came Mikael, whom I thank for all the nice discussions and his help during the last sprint of my PhD. Thank you all for making the office life enjoyable. To the rest of past and present PNO members, thank you all who either helped me greatly during my project, like Mark, Michael, Renaud, Johann, Yury and Vanessa, or simply made lunch, coffee or beer times fun: Jan G, Jan R, Jay D, Mariale, Vale, Chris, Ignacio, Paulina, Pascal, Marko, Pau, Raul, LuisMi, Mathieu, Andreas, Nadine, fRaN, Irene, Mohammed, Gerard, Sebas, Alex, Laurent, Jaime, Vincenzo, Clara, Jordi, Ivan, Victor, Roger, Marc, Bea, and with such a long list I hope I didn´t miss someone important. Special thanks all the ICFO staff that make everything run smoothly and facilitate the life for us. Starting from our director Lluis who´s vision and motivation has taken the institute as far as it goes, and Dolors for making sure it gets there. Infinite thanks go to the HR team lead by Laia, with a special mention to Manu, Mery, Anne and Cristina, thank you for always going the extra mile, and genially caring for us! Thanks to ever present Carlos who keeps ICFO running, and Jonas and Adria for all their logistics efforts. To Xavi´s, Jose Carlos´ and Goncal´s teams at the workshops and IT dept. for their prompt and reliable support. Also to the cleanroom team, Luis, Javi and Johann, thank you for the excellent work i you do in keeping the cleanroom operational. Also thanks to Santi and Magda at purchasing, Elena and Maria for help with travels, and Moni, Maria and Merce for starting our working days with a warm smile. As well as many others who were always willing to help and create a good atmosphere at ICFO (Esther, Rob, Rafa G, Javi E, Thomas, Silvia, Ferran, Alina, Brook, etc). During my PhD I was honoured to take part of several successful collaborations, all of which enriched me as a researcher. In particular, I would like to kindly acknowledge those whom I actively interacted with and gained knowledge from through our discussions: Jerome Wenger and Guillaume Baffou from the Fresnel Institute; Carlos Ballestero, Javi Cuerda, Jorge Bravo and Francisco J García-Vidal from the only “Madrid team” I can be a fan of; Ilya Radko, Cameron Smith and Sergey Bozhevolnyi from Denmark (our source of great V- grooves); and Gozde Tutuncuoglu, Luca Francaviglia and Anna Fontcuberta I Morral from EPFL, whom I thank not only for the great collaboration but also the hospitality during a couple of measuring weeks. The list is too long but I would also thank people from the other groups at ICFO with whom I interacted and made good friendships, from the members of ICONS to those joining the different spare time activities like the fútbol and futbolin groups. A special mention does go to the people whom I establish friendships that go beyond life at ICFO, thank you Michael, Michelle, Jan, Camila, Jon, Nilli, Domi, Iris, Gabi, Nico and Gustavo for the good times together. Thanks to my friends and family in Costa Rica for their unconditional support, in particular to my parents, Leda and Victor, thank you for all the support you´ve always gave me, especially all these years I´ve spent abroad. Finally Dani, thank you for being by my side supporting and encouraging me every single day. ii Abstract The field of photonics comprehends the generation, manipulation and detection of light (photons). Over the past decades, it has underpinned many of the technological advances upon which we rely on a daily basis, from our personal electronic devices and data communication channels (fibre optics), to medical instruments and lighting technologies. In line with this dependence, the photonics community is constantly seeking to develop novel technologies that can enable ever faster and powerful data communications, as well as compact and ultrasensitive monitoring systems. Advances made in this field depend greatly on the understanding and control we have over the light-matter interactions at play, with a strong focus on integrated photonic chip platforms due to their small footprint and scalability potential. One of the main challenges to achieve fully integrated photonic chips deals with the emission coupling from nanoscale light sources to the on-chip photonic components. Ideally, the energy of a given light emitter should efficiently couple to sub-wavelength confined modes in order to fulfil scalability requirements. One solution is to implement metallic structures supporting surface plasmon polariton modes (i.e., coupled oscillations between photons and the free-electrons of the metal), which enable confinements beyond the diffraction limit of light. This thesis deals with the development of hybrid photonic devices that enable the coupling of nanoscale light sources with on-chip plasmonic structures. These hybrid systems allowed us to influence the emission dynamics of the light sources, as well as transferring the emitted energy across the surface of a chip via subwavelength confined propagating modes. We implement state-of-the-art nanopositioning techniques to demonstrate various functioning hybrid devices operating with down to a single nanoscale emitter. We start by exploiting a double high-resolution lithography approach combined with chemical functionalization, to assemble colloidal semiconductor quantum dots (QDs) at the hotspot of plasmonic nanoantennas. The antennas, designed to resonate with the excitation wavelength of our experiment, allow us to study the excitation enhancement provided by the metallic nanostructures by means of fluorescence lifetime measurements. New insights about the limitations of the implemented positioning method are also provided. Next, we turn our attention to explore the potential of a particular type of plasmonic waveguide, namely the V-groove (VG) channel plasmon waveguides, to couple and transfer the emission from various nanoscale light sources across the surface of a chip. The initial experiments explore the coupling of quantum emitters (i.e., particles able to emit single photons) to the supported waveguide modes, with a focus on Nitrogen Vacancy (NV) centres in nanodiamonds and self-assembled QDs in semiconductor nanowires. In both cases, an iii atomic force microscope (AFM) based nanopositioning technique was employed to bring the particles into the VG channels. We demonstrate for the first time in the field, the coupling of these type of quantum emitters to the channel plasmon polariton (CPP) modes supported by the VG waveguides, even down to the single emitter-VG coupling scenarios. Finally, plasmonic waveguide-integrated nanowire laser devices are demonstrated. To achieve this, the AFM nanopositioning technique allow assembling core-shell-cap semiconductor nanowires into wafer-scale compatible VG waveguides. Room temperature operation of this hybrid plasmon nanolaser is realized, with a remarkable performance in terms of the transfer of energy from the hybrid plasmonic-photonic mode to the subwavelength confined propagating CPP mode supported by the VG. The results presented in this thesis contribute to the list of potential hybrid photonic- plasmonic platforms applicable in future integrated photonic chip technologies. In particular, our devices based on the VG plasmonic waveguides, pave the way for the further development of more complex heterogeneous photonic circuitry. iv Resumen El campo de la fotónica comprende la generación, manipulación y detección de la luz (fotones). Durante las últimas décadas, la fotónica ha sido la base de muchos de los avances tecnológicos de los que dependemos diariamente, desde nuestros dispositivos electrónicos personales y canales de comunicación de datos (fibra óptica), hasta los instrumentos médicos y las tecnologías de iluminación.