Purpose: We introduce a novel concept of a compact multiprobe scintillator detector and demonstrate its applicability in HDR-brachytherapy. Our fabricated seven-probe system is sufficiently narrow to be inserted in a brachytherapy needle or in a catheter. Methods: Our multiprobe detection system results from the parallel implementation of a miniaturized scintillator detector at the end of a bundle of seven fibers. The resulting system, which is narrower than 320 microns, is tested with a MicroSelectron 9.1 Ci Ir-192 HDR afterloader, in a water phantom. The detection signals from all seven probes are simultaneously read with an sCMOS camera (at a rate of 0.06 s). The camera is coupled to a chromatic filter to cancel Cerenkov signal induced within the fibers upon exposure. By implementing an aperiodic array of six scintillating cells along the bundle axis (one probe is kept bare to assess the stem effect), we first determine the range of inter-probe spacings leading to optimal source tracking accuracy. Then, three different source tracking algorithms involving sequentially or simultaneously all the scintillating probes are tested and compared. In each case, dwell positions are assessed from dose measurements and compared to the treatment plan. Dwell time is also determined and compared to the treatment plan. Results: The optimum inter-probe spacing for an accurate source tracking ranges from 15 mm to 35 mm. The optimum detection algorithm consists of adding the readout signals from all detector probes. In that case, the error to the planned dwell positions is of 0.01+/-0.14 mm and 0.02+/-0.29 mm at spacings between the source and detector axes of 5.5 and 40 mm, respectively. Using this approach, the average deviations to the expected dwell time are of -0.006+/-0.009 s and -0.008+/-0.058 s, at spacings between source and probe axes of 5.5 mm and 20 mm, respectively.

We propose a novel implementation of a miniaturized photonicplatformfabricated on a multicore fiber tip, capable of tunable optical functionsvia coupling to Bloch surface waves (BSWs). A one-dimensional photoniccrystal is deposited on the cleaved surface of a fiber tip, allowingthe propagation of BSWs in the near-infrared. On top of each core,subwavelength gratings are fabricated to operate as optical couplersbetween BSWs and the corresponding fiber modes. The ability to controlthe optical interconnection among different pairs of cores of themulticore fiber via polarization-selective BSW coupling is demonstrated.The resulting compact, tunable, and portable platforms can be fruitfullyemployed in the vast application domain covered by optical fiber technologyincluding sensing, optical trapping, manipulation, and informationprocessing.

BACKGROUND:In vivo dosimetry (IVD) is gaining interest for treatment delivery verification in HDR-brachytherapy. Time resolved methods, including source tracking, have the ability both to detect treatment errors in real time and to minimize experimental uncertainties. Multiprobe IVD architectures holds promise for simultaneous dose determinations at the targeted tumor and surrounding healthy tissues while enhancing measurement accuracy. However, most of the multiprobe dosimeters developed so far either suffer from compactness issues or rely on complex data post-treatment.PURPOSE:We introduce a novel concept of a compact multiprobe scintillator detector and demonstrate its applicability in HDR-brachytherapy. Our fabricated seven-fiber probing system is sufficiently narrow to be inserted in a brachytherapy needle or in a catheter.METHODS:Our multiprobe detection system results from the parallel implementation of six miniaturized inorganic Gd2 O2 S:Tb scintillator detectors at the end of a bundle of seven fibers, one fiber is kept bare to assess the stem effect. The resulting system, which is narrower than 320 microns, is tested with a MicroSelectron 9.14 Ci Ir-192 HDR afterloader, in a water phantom. The detection signals from all six probes are simultaneously read with a sCMOS camera (at a rate of 0.06 s). The camera is coupled to a chromatic filter to cancel Cerenkov signal induced within the fibers upon exposure. By implementing an aperiodic array of six scintillating cells along the bundle axis, we first determine the range of inter-probe spacings leading to optimal source tracking accuracy (first tracking method). Then, three different source tracking algorithms involving all the scintillating probes are tested and compared. In each of these four methods, dwell positions are assessed from dose measurements and compared to the treatment plan. Dwell time is also determined and compared to the treatment plan.RESULTS:The optimum inter-probe spacing for an accurate source tracking ranges from 15 to 35 mm. The optimum detection algorithm consists of adding the readout signals from all detector probes. In that case, the error to the planned dwell positions is of 0.01 ± 0.14 mm and 0.02 ± 0.29 mm at spacings between the source and detector axes of 5.5 and 40 mm, respectively. Using this approach, the average deviations to the expected dwell time are of - 0.006 ± 0.009 $-0.006\,\pm \,0.009$ s and - 0.008 ± 0.058 $-0.008\, \pm 0.058$ s, at spacings between source and probe axes of 5.5 and 20 mm, respectively.CONCLUSIONS:Our six-probe Gd2 O2 S:Tb dosimeter coupled to a sCMOS camera can perform time-resolved treatment verification in HDR brachytherapy. This detection system of high spatial and temporal resolutions (0.25 mm and 0.06 s, respectively) provides a precise information on the treatment delivery via a dwell time and position verification of unmatched accuracy.

Optically-induced magnetism has drawn considerable interest in the past years for its ability to speed up magnetic processes. For example, static magnetic fields have been demonstrated to be generated in non-magnetic plasmonic (gold) nanoparticles and nano-apertures [1]. Such a phenomenon has been analyzed as the result of the inverse Faraday effect. Inverse Faraday effect in plasmonic structures can be predicted with a hydrodynamic description of the free electron gas of a metal [2]. More generally, the hydrodynamic model provides reference equations for describing optical nonlinearities in plasmonic nanostructures [3]. It is usually admitted that the inverse Faraday effect (IFE) originates from the spin angular momentum (SAM) of light. We evidence that part of the IFE in metals is induced by the orbital angular momentum (OAM) of light[4]. Using a simplified hydrodynamic model of the free electron gas of a metal, we theoretically investigate the IFE and resulting optomagnetism in a thin gold film as well as in axis-symmetric plasmonic nanostructures under illumination with various focused light beams carrying spin and/or orbital angular momenta [5, 6]. The resulting static magnetic field exhibits resonant behaviour and found to be maximum and dramatically confined at the corners and edges of the plasmonic structures, which reveals the ability of metallic discontinuities to concentrate and tailor static magnetic fields on the nanoscale. Plasmonics can thus generate and tune static magnetic fields and strong magnetic forces on the nanoscale, potentially impacting small scale magnetic tweezing and sensing as well as the generation of magneto-optical effects and spin-waves.

It is usually admitted that the inverse Faraday effect (IFE) originates from the spin angular momentum (SAM) of light. In this paper, we evidence that part of the IFE in a metal is induced by the orbital angular momentum (OAM) of light. On the basis of a hydrodynamic model of the conduction electron gas, we describe the dependence of the IFE on the spin and orbital angular momenta as well as spin-orbit interaction in a non-paraxial light beam. We also numerically quantify the relative contributions of the SAM and OAM of light to the IFE in a thin gold film illuminated by different focused beams carrying SAM and/or OAM. The OAM of light provides a new degree of freedom in the control of the IFE and resulting optomagnetic field, thus potentially impacting various research fields including all-optical magnetization switching and spin-wave excitation.

We introduce a nano-optical platform based on Bloch surface waves (BSWs) capable of exploiting the entire cleaved end facet of a multicore optical fiber. Interconnecting various fiber cores with BSWs directly at the end of a multicore fiber opens the perspective of highly compact complex optical functionalities for the design of “lab on fiber” devices. In counterpart, optical fibers provide a unique opportunity to obtain turnkey nano-optical functions addressing a vast application domain ranging from telecommunications to medical sensing. To show the full potential of our platform, we demonstrate a multiplexing function between three fiber cores.

We introduce a nano-optical platform based on Bloch surface waves (BSWs) capable of exploiting the entire cleaved end facet of a multicore optical fiber. Interconnecting various fiber cores with BSWs directly at the end of a multicore fiber opens the perspective of highly compact complex optical functionalities for the design of “lab on fiber” devices. In counterpart, optical fibers provide a unique opportunity to obtain turnkey nano-optical functions addressing a vast application domain ranging from telecommunications to medical sensing. To show the full potential of our platform, we demonstrate a multiplexing function between three fiber cores.

Activity and release of myeloperoxidase (MPO) was measured in heparinized whole blood samples after activation of neutrophil granulocytes by the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (fMLP) using two different methods: (i) by determination of theamountof MPO released into the blood plasma using a MPO enzyme-immunoassay, and (ii) simultaneously, by measuring the remainingactivitywithin the neutrophils by flow cytometry using the Bayer Technicon H3. Although a part of MPO was released immedi ately after addition of fMLP, remaining MPO activity within the neutrophils surprisingly increased during the first minutes after incubation. Subsequently, MPO activity dropped due to a continuous release of MPO. In addition to fMLP, granulocyte-macrophage colony stimu lating factor (GM-CSF) enhanced MPO activity in neutrophils. These results indicate that MPO is present in resting granulocytes in an inactive or only partially active form and is activated by fMLP and GM-CSF.

: We provide a spin and orbital angular momentum representation of the inverse Faraday effect in a metal. We analytically show the role of the spin and orbital angular momenta of light (SAM and OAM, respectively), as well as the spin-orbit interaction (SOI), in the generation of an optoinduced magnetization. We also show that resonances in plasmonic nanoantennas enhance and confine the IFE on the nanoscale, thereby leading to static magnetic fields directly applicable in a vast application domain including all-optical magnetization switching and spin-wave excitation. Light is known to possess polarization and spatial degrees of freedom, manifested by its linear momentum as well as spin and orbital angular momenta[1]. Remarkably, the SAM of light can be transferred to electrons in matter, a phenomenon which refers to as the IFE [2, 3]. The IFE has attracted much attention for its ability to generate light-induced magnetization, thereby opening the prospect of an ultrafast magnetic data storage and a non-contact excitation of spin-waves. On the basis of a hydrodynamic model of the conduction electron gas [4, 5], we provide a spin and orbital angular momentum representation of the IFE in a metal [6]. The OAM and SOI of light provide additional degrees of freedom in the control of the IFE usually solely attributed to the SAM. We also investigate a resonant IFE within individual nanoantennas [7, 8]. Upon illumination, individual subwavelength gold coaxes and cylinders are shown to develop a strong optomagnetic field on the nanoscale that is controllable by the helicity of the light. In pulse optical regime, this magnetic field is found to reach 0.3 T upon excitation

We theoretically investigate a resonant inverse Faraday effect within individual coaxial nanoapertures. Upon illumination with circularly polarized light, resonant gold coaxes are shown to develop an optomagnetic field that is controllable by the helicity of the light. This magnetic field is found to reach 0.13 T upon excitation at an intensity of 0.5 · 1011W.cm−2 that is typical from sub-ps light pulses. At an intensity of 2.4 · 108W.cm−2 (consistent with the CW regime), we obtain a static magnetic field of about 1 mT, leading to a helicity-dependent magnetic force of 4.5 · 106 N onto a point-like magnetic dipole of unit moment. Given their submicron footprint, individual coaxial nanoapertures open new prospects towards ultrafast and polarization-controlled tunable magnetism on the nanoscale, thus potentially impacting a large panel of application and techniques including all optical magnetization switching, spin-wave excitation and optomagnetic tweezing of nano-objects.

Using a simplified hydrodynamic model of the free electron gas of a metal, we theoretically investigate optically induced DC current loops in a plasmonic nanostructure. Such current loops originate from an optical rectification process relying on three electromotive forces, one of which arises from an optical spin-orbit interaction. The resulting static magnetic field is found to be maximum and dramatically confined at the corners of the plasmonic nanostructure, which reveals the ability of metallic discontinuities to concentrate and tailor static magnetic fields on the nanoscale. Plasmonics can thus generate and tune static magnetic fields and strong magnetic forces on the nanoscale, potentially impacting small scale magnetic tweezing and sensing as well as the generation of magneto-optical effects and spin waves.

This erratum amends two errors in Opt. Lett.46, 613 (2021)OPLEDP0146-959210.1364/OL.411108.

We report on a LiNbO3 microresonator integrated in a low-loss free-suspended waveguide. The photonic elements are made by optical-grade dicing, and are assembled dynamically. This method opens the way to new 3D photonic architectures.

Lithium niobate (LiN bO3) microresonators have attracted much interest over the last decade, due to the electrooptical, acousto-optic and non-linear properties of the material, that can advantageously be employed in combination with thin resonances of optical microcavities for applications as varied as integrated gyrometers, spectrometers or dynamic filters. However the integration of micrometer scale cavities with an input/output waveguide is still a critical issue. Here we propose an innovative approach, allowing low insertion losses and easy pigtailing with SMF fibers. The approach consists in producing and optimizing separately a membrane-based LiNbO3 waveguide with Spot-Size Converters, and a thin microdisk. The two elements are dynamically assembled and fixed in a second step. Additionally to the proposed integrated microresonator, this approach opens the way to the production of 3D hybrid photonic systems.

: We report on the production of hybrid photonic microsystem made by the dynamic structuration and assembly of photonic building blocks in F.I.B. (Focused Ion Beam) environment. More particularly, we show how to produce a low-loss integrated LiNbO 3 resonator composed of a free-suspended microguide and a microdisk, which shows great potential for electro-optic sensors or comb generators. The method opens the way toward new 3D electro-optical or mechanical hybrid photonic micro and nanosystems.