Fabbricazione nanofotonica assistita dai fononi e mediata dalle fluttuazioni e sue applicazioni

Responsabili di progetto

Mario Santoro, Takashi Yatsui

Accordo

GIAPPONE - JSPS - Japan Society for the Promotion of Science

Bando

CNR/JSPS 2014-2015

Dipartimento

Scienze fisiche e tecnologie della materia

Area tematica

Scienze fisiche e tecnologie della materia

Stato del progetto

Nuovo

Proposta di ricerca

Nanophotonics is stimulating an increasing interest for the wide range of applications that manipulation and control of light in nanosized, integrated, devices can have in future technologies. A number of approaches has been deployed in order to find efficient fabrication methods for nanophotonic systems. In some cases, for instance when noble metal nanostructures have to be realized as in plasmonics, electron beam lithography (EBL) has demonstrated to be a viable method. However, the inherently serial character of EBL leads to limited fabrication yield, which is often deemed not compatible with large scale fabrication. Moreover, while the utility of plasmonics in guiding and modifying the electromagnetic field in sub-wavelength sized regions has been widely demonstrated, it can be hardly used to obtain photon sources, which are key ingredients for many photonic implementations. Within this frame, nanosized objects able to emit on demand single photons in antibunching conditions offer unprecedented possibilities for optical quantum information, communication, cryptography [see, e.g., B.Lounis and M.Orritt, Rep. Prog. Phys, 68, 1129 (2995)]. In order to be exploitable in practical applications, solid-state arrays of single photon sources have to be conceived such as, for instance, defects in dielectrics acting as color centers and semiconductor quantum structures.
Near-field optics is naturally involved in nano-optics and nanophotonics, since it represents a viable, and often unique, method to couple light with nanosized objects as well as to manipulate radiation in a size scale smaller than the wavelength. The non-propagating character of the near-field has been widely used in realizing microscopy methods virtually free of the spatial resolution limitations due to diffraction. The Scanning Near-field Optical Microscope (SNOM), originally introduced as a variant of scanning probe microscopy [D.W.Pohl, et al., Appl. Phys. Lett. 44, 651 (1984); A.Lewis, et al., Ultramicroscopy 13, 227 (1984)], has been shown to be a powerful tool for optical investigations at the nanoscale. For instance, past Japanese-Italian collaborative efforts between some of the members of the present consortium ["Near-field polarization contrast for nano-optics applications", Italy-Japan S&T Cooperation, Executive Programs 2005/07 and 2008/09, PIs M.Allegrini, Pisa, and R.Micheletto, Kyoto/Yokohama] led to implement sophisticated polarization-modulation methods to SNOM [P. G.Gucciardi, et al., pp. 318-356 in "Applied Scanning Probe Methods II: Scanning Probe Microscopy Techniques (nanoscience and nanotechnology)", Springer (2005)]. Applications to semiconductor quantum wells [R.Micheletto, et al., J. Appl. Phys. 99, 084303 (2006); Appl. Phys. Lett. 89, 121125 (2006); J.Opt.A 9, 431 (2007); Opt. Expr. 16, 6889 (2008); Appl. Phys. Lett. 95, 211904 (2009)] demonstrated the ability to catch the details of the optical emission with a spatial resolution (tens of nanometers) adequate to investigate single emitters.
Near-field technologies are the main component of the present project, where they will be used with two distinct, while strongly interconnected, aims. On one hand, the already mentioned capabilities of SNOM will be used to investigate samples and materials of interest for the project. Such a task will provide the project with information complementary to those achieved with the range of more conventional techniques available within the consortium.
On the other hand, a more original and potentially relevant objective is proposed as a distinctive and original feature of the project that foresees exploring and assessing the potential of near-field technologies for the fabrication of nanophotonics systems.
The achievement of such a challenging objective will be made possible thanks to multinational involvement put together in the project. The Italian team owns a well-established competence in optics, optoelectronics, nano-optics, nanophotonics, and material science and can offer to the project a full range of facilities for optical and structural investigations, including near-field microscopes and the ability to design, realize and develop specific configurations of near-field nanoscopy. The Japanese applicants will provide the project with their unique competence in the area of near-field based nanofabrication.
In particular, they have experimentally clarified a characteristic of near-field light, namely, the coupling of photons with electrons and phonons inside nanomaterials. Such properties show that the function of near-field light should not be considered as mere localization but, more appropriately, as the coupling of material excitation and photons, neatly described in the form of Dressed Photons (DPs) [see, e.g., M.Ohtsu, pp. 1-58 in "Progress in Nanophotonics 1", Springer (2011); "Dressed Photons: Concepts of Light-Matter Fusion Technology", Springer (2013)]. By further coupling with phonons, DPs can excite phonon states in the electron ground states that are impossible to excite using the propagating far-field light and that can be used to achieve efficient morphological control of different material surfaces such as, diamond, oxides, semiconductors [T.Yatsui, et al., J. Phys. D 45, 475302 (2012); Appl. Phys. B 107, 637 (2012); H.Tanaka, et al., Appl. Phys. B 108, 51 (2012); T.Kawazoe, et al., Appl. Phys. B 107, 659 (2012)]. DPs can also enable multi-step transitions mediated via the allowed electric dipole states. In addition, the Japanese team recently succeeded in fabricating new nano-composites by controlling the fluctuation of nanoparticles with DPs and employing a hierarchical fabrication mechanism [M.Naruse, et al., Appl. Phys. Lett. 102, 071603 (2013)], a route that will be also explored within the present project.
The activity of the project is broken into three different tasks (with sub-tasks), each one related to a specific objective, as detailed in the Objective and Time Plan sections.

Obiettivi della ricerca

The project aims at exploring and assessing the opportunities offered by near-field technologies, already well demonstrated in the area of nanoscopy, in the area of nanofabrication, applied in particular to nanophotonic systems such as single photon sources. The Italy-Japan consortium puts together complementary state-of-the-art competence and facilities for the fulfillment of the proposed goal.
Goal of the project, to be pursued thanks to the expertise in near- and far-field optical analysis and related applications mastered by the Italian team, is to further extend the Dressed-Photon (DP) technologies invented by the Japanese team towards fields of strong mutual interest, from both the fundamental and applicative points of view.
--Specific objectives of the project are:
--OBJ1: using DP for the nanofabrication of nano-diamond single photon sources and analyzing their properties with a variety of optical diagnostics, including those based on near-field collection;
--OBJ2: investigating photon interaction processes leading to blinking effects in quantum emitters, both at the macroscopic and nanoscopic scales;
--OBJ3: extending near-field based technologies towards the inclusion of fluctuation-driven effects, in order to improve the performance of the related nanofabrication and analytical approaches.
The fulfillment of the aforementioned objectives is broken into corresponding tasks. The team involvement and the time schedule for each task are listed in the Time Plan section.

Ultimo aggiornamento: 14/06/2025