The negatively charged nitrogen-vacancy color center in diamond has been identified as a sensitive magnetic field sensor based on the optically detected magnetic resonance (ODMR). However, it requires knowledge of the crystal axes and it needs an external magnetic bias field to measure the field’s orientation, or the use of single centers. Recently, by combining ensembles of color centers with polarimetry, we have been able to determine the magnitude and direction of an unknown magnetic field. The out-of-plane polarization components of the excitation laser create asymmetry in the polarization resolved ODMR spectrum. This provides the necessary conditions to reconstruct the three-dimensional magnetic field vector without a bias field. Our approach is general for other spin-1 color centers with the same symmetry, and it is compatible with standard microscopy methods, such as scanning probe, super-resolution, confocal, and wide-field imaging.
Diamond offers unique opportunities for applications in photonics, essentially because its very large band-gap leads to a wide transparency window and to the availability of numerous color centers. However, it is still challenging to obtain scalable and reproducible optoelectronics based on these defects. An important aspect in this respect is represented by the feasibility of electroluminescence devices, which combine diamond electronics with the photo-physics of color centers. Here, we demonstrate electrically-driven light emission from color centers based on a phosphorous-doped diamond Schottky diodes. Compared to conventional p-i-n systems, our approach simplifies the fabrication process, and it promotes the implementation of novel light sources based on diamond.
Diamond has emerged as promising platform for quantum science and technology in virtue of the unique properties of its color centers. The efficient interrogation of such centers optically and electrically remains a fundamental aspect towards quantum applications. We discuss our recent work on the silicon and nitrogen vacancy centers, where both nano-optics and electronics are taken into play. Specifically, we will focus on ultrafast single-photon emission, electroluminescence, nanoscale temperature sensing and vector magnetometry.
KEYWORDS: Ultrafast phenomena, Quantum efficiency, Near field optics, Luminescence, Single photon, Silicon, Signal detection, Polarizers, Plasmonics, Near field
We discuss theoretical and experimental results on the ultrafast detection of quantum emitters. We employ nano-antennas, specifically gold nanocones, to accelerate the spontaneous emission rate of silicon-vacancy color centers in diamond by orders of magnitude to generate single photons with picoseconds timescales. Moreover, we implement an optical Kerr shutter under tight focusing to be able to detect such ultrafast single photons with time resolutions down to a few hundreds of femtoseconds.
Editorial board members Chao-Yang Lu (Univ. of Science and Technology of China) and Mario Agio (Univ. of Siegen and CNR-INO) present an Advanced Photonics collection spotlighting quantum science and technologies.
Sepsis, defined as the systemic inflammatory response to a confirmed or suspected source of infection, is the most severe infection-related condition and its identification can be particularly difficult in the initial stages. The importance of having a Point-of-care testing platform capable of measuring sepsis biomarkers for a secure early-stage diagnosis is evident to reduce delay in treatment and hence recovery period for the patient.
We will report on a simple and cost-effective device which also shows high portability. It is based on the optical detection of labeled essays through a fully-automated fiber probe. Efficient signal collection is obtained by replacing the standard glass substrate with a planar metallo-dielectric multilayer which funnels the emission into a narrow cone around the polar axis [1]. Optical interrogation is implemented with a minimized epi-fluorescence monolithic system directly connected to the fiber.
On one hand, optical probes provide the ability to detect low quantities of target molecules without direct contact to the sample; on the other hand, nano-photonics promises to overcome the limitations related to bulk optics with precise and fragile alignment procedures.
We will report on preliminary results obtained for a reference dry essays (IgG/anti-IgG) marked with ATTO647N, which demonstrates sensitivity overcoming the requirements for CRP-based sepsis detection. We will also discuss optimization steps which are expected to bring sensitivity beyond the level required for PRC-based sepsis detection. The proposed device is also prone to implementation in microfluidic-based protocols.
[1] Checcucci S, Lombardi P., Rizvi S., Sgrignuoli F., Gruhler N., Dieleman F.B.C., Cataliotti F.S., Pernice W.H.P., Agio M., and Toninelli C., Beaming light from a quantum emitter with a planar optical antenna, Light: Science and Applications, Vol. 6, e16245 (2017).
Fluorescence detection is a well-established method for spectroscopy and sensing. However, since dye molecules are dipolar light sources, a large fraction of the emitted photons can be lost. An effective approach to overcome this problem relies on a planar antenna configuration, which beams the radiation pattern of the dye into a narrow cone. A planar antenna works like a Yagi-Uda antenna, but reflector and director elements are made of thin metal films. Here, by introducing a scanning optical fiber, which incorporates the reflector or the director, we demonstrate a tunable planar antenna for spectroscopic and sensing applications. Our results show that the radiation pattern narrows down to 26 degrees (FWHM), which implies a high collection efficiency by low-NA optics.
Sepsis, defined as the systemic inflammatory response to a confirmed or suspected source of infection, is the most severe infection-related condition and its identification can be particularly difficult in the initial stages. The importance of having a POCT platform capable of measuring sepsis biomarkers for a secure early-stage diagnosis is evident since traditional methods of pathogen determination delay treatment and also increase the recovery period for the patient. The biggest advantage of optical probes is the ability to detect low quantities of target molecules without direct contact to the sample. Nanophotonics-based sensing promises to build on the advantages of optical sensing, while overcoming its limitations by providing a high sensitivity, specificity, dynamic range, as well as the possibility for easy integration into simple and affordable devices. The project FASPEC (Fiber-based planar antennas for biosensing and diagnostics) aims at developing and prototyping a high-performance fluorescence-based molecular assay for in-vitro diagnostics that integrates lab-on-a-chip and optical readout functionalities within a single, fully automated platform. The key biophotonics innovation of the project is the replacement of the bulk optics used for collecting the fluorescence signal with a suitably designed optofluidic chip. The latter shall function as an optical antenna to direct fluorescence towards the sensor head, hence enhancing the sensitivity of the fluorescence-based assay by orders of magnitude. Application-specific lab-on-a-chip systems equipped with our high-throughput and ultrasensitive detection scheme have been envisioned.
H. Kambalathmana, A. M. Flatae, S. Lagomarsino, H. Galal, F. Tantussi, G. Messina, E. Wörner, C. Wild, N. Gelli, S. Sciortino, L. Giuntini, F. De Angelis, M. Agio
Silicon-vacancy (SiV) color centers in diamond offer novel possibilities to probe light-matter interaction in nano-quantum optics and provide a scalable quantum system suitable for single-photon emission. However, their effective count-rate is still limited by non-radiative decay channels, radiation at wide angles and total internal reflection at the diamond interface. Recently optical antennas have been utilized in order to modify light-matter interaction at the nanoscale. Acting as resonators, they are able to increase the spontaneous emission rate of quantum emitters by several orders of magnitude in a broad spectral range. Because coupling a quantum emitter to a nano-antenna requires close proximity between the two systems, we implant Si ions on very thin diamond membranes that provide the required dimension for near-field interaction in a controlled manner and investigate the optical properties of SiV color centers in such diamond membranes. We consider gold nano-cones as nano-antennas, fabricated by focused electron beam induced deposition (EBID), followed by sputtering and focused ion beam (FIB) milling. The finite-difference time-domain (FDTD) calculations show that gold nano-cones can provide more than four orders of magnitude enhancement in the Purcell factor with an antenna efficiency (AE) of 80%.
The COST Action MP1403 “Nanoscale Quantum Optics” (NQO) has recently released a NQO Roadmap identifying research priorities that address both classical and quantum schemes in information and communication technology, sensing and metrology, and energy efficiency. Based on the Roadmap, the COST Action has been working on a Market Research Study (MRS) to assess the potential of NQO for selected applications and markets in a more quantitative manner. The MRS has been carried out with the cooperation of Tematys and it has been focused on two areas: (i) quantum sensing, imaging and measurement systems: achieve unprecedented sensitivity, accuracy and resolution in measurement and imaging by coherently manipulating quantum objects and (ii) quantum communications: guarantee secure data transmission and long-term security for the information society by using quantum resources for communication protocols. The MRS has primarily addressed near-term technologies, like quantum random number generators (QRNG) for secure key or token generation and point-to-point quantum key distribution (QKD) for secure key exchange in crypto systems. Mid/long-term technologies like QKD networks, quantum memories and repeaters have not been assessed. Likewise for quantum sensing, imaging and metrology the focus has been on near-term technologies like magnetic resonance imaging (MRI), magnetic/electric field detection for materials analysis and biosensing, precision metrology and gravimetric sensors for civil and defense applications. The MRS has also taken into account quantum enabling technologies, which are fundamental components for the construction of quantum-photonics systems.
We investigate the interaction of focused Gaussian and
radially-polarized beams with a silver nanosphere, with
emphasis on the coupling to localized surface plasmon-polaritons. We discuss the overall efficiency, including
the effect of the entrance pupil and of absorption in the nanosphere, showing that a Gaussian beam performs
better than a radially-polarized beam, when focused by an aplanatic system. We find that more than 50% of
the photons in the incident beam can be reflected using realistic focusing parameters.
Mario Agio, Giorgio Mori, Franziska Kaminski, Lavinia Rogobete, Sergei Kühn, Victor Callegari, Philipp Nellen, Franck Robin, Yasin Ekinci, Urs Sennhauser, Heinz Jäckel, Harun Solak, Vahid Sandoghdar
We study the fluorescence enhancement of a single emitter coupled to two spherical gold nanoparticles and
discuss the differences with respect to coupling to a single one. We also show that by changing the aspect
ratio of the nanoparticles we can easily tune the plasmon-mediated enhancement from the infrared to the visible
range. We present the fabrication of our nanoantennae by two alternative methods, namely X-ray interference
lithography followed by focused ion beam milling and electron beam lithography. The manufactured structures
are characterized individually by confocal microscopy.
Photonic modes in 1-D and 2-D silicon-on-insulator photonic
crystal waveguides periodic or containing line-defects, are fully
explored by means of angle- and polarization-resolved
micro-reflectance measurements. Both quasi-guided and truly guided
photonic modes are probed with a frequency-wave vector range that
is greatly expanded under attenuated total reflectance
configuration. It is shown that the presence of a supercell
repetition in the direction perpendicular to a line defect leads
to the simultaneous excitation of defect and bulk modes folded in
a reduced Brillouin zone. Consequently, the group-velocity
dispersion of the defect modes corresponding to different
polarizations of light can be fully determined. We show also that
the measured dispersion is in good agreement with full 3D
calculations based on expansion in the waveguide modes.
Practical realizations of 2D (planar) photonics crystal (PhC) are either on a membrane or etched through a conventional heterostructure. While fascinating objects can emerge from the first approach, only the latter approach lends itself to a progressive integration of more compact PhC's towards monolithic PICs based on InP. We describe in this talk the various aspects from technology to functions and devices, as emerged from the European collaboration "PCIC." The main technology tour de force is deep-etching with aspect ratio of about 10 and vertical sidewall, achieved by three techniques (CAIBE, ICP-RIE, ECR-RIE). The basic functions explored are bends, splitters/combiners, mirrors, tapers, and the devices are filters and lasers. At the end of the talk, I will emphasize some positive aspects of "broad" multimode PhC waveguides, in view of compact add-drop filtering action, notably.
Photonic crystals have seen major advances in the past few years in the optical range. The association of in-plane waveguiding and two-dimensional (2D) photonic crystals (PCs) in thin-slab or waveguide structures leads to good 3D confinement with easy fabrication. Such structures, much easier to fabricate than 3D PCs, open many exciting opportunities in optoelectronic devices and integrated optics. We review the basics of these structures, with emphasis on basic properties and loss performance, as well as modeling tools, which show that 2D PCs etched through waveguides supported by substrates are a viable route to high-performance PC-based photonic integrated circuits (PICs). A companion paper by Benisty et al. in these proceedings illustrates further high performance building blocks and integrated devices.
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