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We present a new optical biosensing integration approach with multifunctional capabilities using plasmonic and photonic components on the same chip and a new methodology to design interferometric b...

We demonstrate a water cladded plasmo-photonic waveguide, by exploiting the directional coupling scheme to vertically divert light from a 360 × 800 nm (height × width) Si3N4 waveguide to a plasmonic slot waveguide, enabling the excitation of a pure plasmonic mode within a 210-nm-wide slot at 1550 nm. The 150-nm-thick plasmonic slot waveguide was deposited on the top of an oxide cladded Si3N4 waveguide exhibiting an experimental plasmonic-to-photonic insertion loss of 2.24 ± 0.3 dB and a plasmonic propagation length (Lspp) of 10.8 μm at 1550 nm. The proposed plasmo-photonic waveguide holds a promise as an optical transducer element for highly sensitive and low-cost interferometric biosensors due to the significant phase change achieved per unit propagation length.

Optical refractive index (RI) sensors exploiting selective co-integration of plasmonics with silicon photonics in Lab-on-achip configurations are expected to disrupt Point-of-Care (POC) diagnostics, delivering performance and economic breakthroughs. Propagating surface-plasmon-polariton modes offer superior sensitivity due to their extreme overlap with the surrounding medium. In parallel, low-loss photonics act as the hosting platform with which the plasmonic losses can be sustained while allowing for multiplexed layouts via in-plane SPP excitation schemes. However, merging plasmonics with silicon photonics in a cost-effective manner, requires a truly CMOS-compatible manufacturing process. Herein, we demonstrate experimentally, the highest bulk-sensitivity among all the plasmo-photonic interferometric RI sensors, while taking the leap forward in the development of a CMOS-manufactured plasmo-photonic sensing platform merging Si3N4 photonics and aluminum plasmonics. The proposed structure relies on a butt-coupled interface between Si3N4 waveguides and a 70 μm long plasmonic stripe, deployed in one branch of a Mach-Zehnder Interferometer (MZI) serving as the sensing transducer that detects local changes in the refractive index. The lower MZI arm (reference arm) exploits the low-loss Si3N4 platform to deploy a MZI-based variable optical attenuator followed by a thermo-optic phase shifter to optimize the sensor performance achieving resonance extinction ratio values at the MZI output of more than 35 dB. Experimental evaluation of a gold-based sensor revealed a bulk refractive index sensitivity of 1930 nm/RIU. In addition, we experimentally demonstrate that the proposed plasmo-photonic waveguide platform can migrate from gold (Au) to Aluminum (Al), demonstrating the first step towards a fully CMOS compatible plasmo-photonic interferometric sensor.

We demonstrate a CMOS compatible interferometric plasmo-photonic sensor exploiting SisN4 photonic and aluminum (Al) plasmonic stripe waveguides. Experimental evaluation revealed bulk sensitivity of 4764 nm/RIU, holding promise for ultra-sensitive and low cost sensing devices.

Optical refractive-index sensors exploiting selective co-integration of plasmonics with silicon photonics has emerged as an attractive technology for biosensing applications that can unleash unprecedented performance breakthroughs that reaps the benefits of both technologies. However, towards this direction, a major challenge remains their integration using exclusively CMOS-compatible materials. In this context, herein, we demonstrate, for the first time to our knowledge, a CMOS-compatible plasmo-photonic Mach-Zehnder-interferometer (MZI) based on aluminum and Si3N4 waveguides, exhibiting record-high bulk sensitivity of 4764 nm/RIU with clear potential to scale up the bulk sensitivity values by properly engineering the design parameters of the MZI. The proposed sensor is composed of Si3N4 waveguides butt-coupled with an aluminum stripe in one branch to realize the sensing transducer. The reference arm is built by Si3N4 waveguides, incorporating a thermo-optic phase shifter followed by an MZI-based variable optical attenuation stage to maximize extinction ratio up to 38 dB, hence optimizing the overall sensing performance. The proposed sensor exhibits the highest bulk sensitivity among all plasmo-photonic counterparts, while complying with CMOS manufacturing standards, enabling volume manufacturing.

Plasmonics have been identified as an ideal platform for ultra-sensitive, label-free biosensors mainly due to the high field confinement on a metal-dielectric interface and the resulting strong light-matter interaction offered by surface plasmon resonances (SPRs) that can be entirely exposed to test analytes. Well-established SPR-based biosensors exploiting propagating SPRs yield superior specifications regarding bulk sensitivity compared to localized counterparts leading to already commercial available sensor devices. However, most of these systems require bulky prism-based configurations to couple light into the Surface Plasmon Polariton (SPP) mode impeding system miniaturization. In addition, SPR-based sensors suffer from intrinsic high propagation losses restricting the potential for multiple on-chip functionalities. In this context, co-integration of plasmonics with a low-loss photonic platform emerges as a viable solution towards highly sensitive, low-loss and small footprint optical sensors. In this work, we present an ultra-compact, interferometric plasmonic sensor co-integrated on a TiO2 photonic waveguide platform. The device consists of two access TiO2 photonic waveguides separated by a gold-based metal stripe which is located on top of an appropriately shorter TiO2 waveguide layer. Two metal/insulator interfaces are formed at the top (sensing arm) and bottom surfaces (reference arm) of the metal able to support SPP modes which upon excitation through the input photonic waveguide propagate along the two metal surfaces and interfere at the output waveguide realizing a single-arm Mach-Zehnder Interferometer. After optimization of the device in aqueous environment, we achieved sensitivity values as high as 2430 nm/RIU at near-infrared spectrum region for a 65 um long plasmonic stripe.

Grating couplers are the most versatile mechanism to couple light efficiently into photonic interconnects, such as waveguides featuring submicronic cross-sections. Usually grating couplers are used in a tilted illumination configuration in order to obtain unidirectional excitation of the waveguide, requiring challenges in assembly and packaging. In practical applications, tilted illumination of the gratings is not always possible in particular for fully integrated electrooptical printed circuit board (EO-PCB) with a light source (Vertical-Cavity Surface-Emitting Laser (VCSEL)) and an optical layer implanted on each side of the board. In this case, the incoming light hits the gratings couplers at normal incidence and specific strategies are needed to achieve unidirectional excitation of the guided mode. In this work, a novel unidirectional Data Center coupling concept based on the use of gap plasmon polariton (GPR) grating couplers sustained by Metal-Insulator-Metal (MIM) resonators is introduced. Unlike traditional challenging subwavelength coupling schemes based on plasmonics and Si-Photonics, we consider non-symmetric GPR featuring highly directional scattering efficiency. The plasmonic gratings have been modelled numerically employing a Fourier Modal Method and the results have been confirmed by FEM simulations.

Plasmonic sensors, leveraging the profound exposure of propagating Surface-Plasmon-Polariton (SPP) modes over metal stripes to test analytes, became so far the “gold-standard” in plasmonic biosensing resulting in commercial available devices. However, a series of challenges associated with their bulky prism-based coupling configuration as well as their high optical losses need to be overcome in order to allow for miniaturized and multiplexed sensor layouts. In this context, selective co-integration of plasmonics with low-loss silicon-nitride photonics emerges as a promising solution towards addressing these challenges yet reaping the benefits from both technologies. In this work, we present an interferometric sensor based on a Mach-Zehnder device, where a “plasmo-photonic” waveguide branch is utilized to interrogate changes in the refractive index of a test analyte exploiting the accumulated phase change of the SPP mode being exposed in an aqueous solution. More specifically, the “plasmo-photonic” Mach-Zehnder sensor incorporates a gold plasmonic stripe with a length of 70 μm and a width of 7 μm that has been interfaced with Si3N4 waveguides by means of a butt-coupled interface. By conducting numerical simulations and considering the dispersion properties of the involved materials, we optimized the structural parameters of the sensor aiming at ultra-high bulk sensitivity in the order of micrometres per Refractive Index Unit (RIU).

In biomedicine and biophysics, the discrimination of protein conformations is of critical importance for identifying the unfolding states in the diagnosis of neurodegenerative diseases. We develop a dynamic Raman spectroscopic approach based on a statistical analysis of the time series of spectral fingerprints of single protein. We show that the unfolded state of bovine serum albumin can be identified in the time series using the fluctuations of the Raman bands of some amino acids, tryptophan, tyrosine, leucine, and histidine, acting as biomarkers. The statistical analysis induces also the sorting between physisorption and chemisorption events. This is confirmed by the spectral analysis of the different characteristic spectra highlighted based on the amino acids fingerprints following, notably, the hydrophobicity

International audience; We report the development of titanium dioxide-based waveguides for applications in the near-and mid-infrared. Thanks to embedded metal grating couplers, we demonstrate error free 10 Gbit/s optical transmissions at 1.55 and 2 µm. With additional management of the dispersion profile, we also demonstrate octave spanning supercontinuum in cm-long TiO2 waveguides.

Integration of plasmonic waveguides with low-loss photonic platforms have attracted research efforts as the means to benefit from the extra-ordinary features of plasmonics while enhancing the functional portfolio of Photonic Integrated Circuits (PICs). In this work, we review a technology platform that integrates water cladded plasmonic waveguides integrated in a low-loss Si 3 N 4 photonic platform, targeting biosensing applications. Results obtained experimentally and numerically will be presented with respect to propagation losses, interface coupling loss and accumulated phase change per unit length, showing how Surface Plasmon Polariton (SPP) waveguides can be effectively combined with photonic components in order to demonstrate low-cost and ultra-sensitive optical biosensors.

International audience; We report on the experimental generation of an octave-spanning supercontinuum in a 2.2 cm-long titanium dioxide optical waveguide with two zero dispersion wavelengths. The resulting on-chip supercontinuum reaches the visible wavelength range as well as the mid-infrared region by using a femtosecond fiber laser pump at 1.64 µm.

The Raman intensity fluctuations are the initial source of a lack of accuracy or reproducibility of SERS based nanosensors to reliably estimate the molecular concentration in microfluidics. Here, we show that the statistical analysis of the weighting of Raman scattering of the probed molecules compared to the photoluminescence of gold nanoparticles is particularly effective as a concentration indicator in a single molecule regime. We present a novel approach in the Fourier domain that is not limited by a multipoint precalibration or even the knowledge of the enhancement factor of the transducer. The analysis of pink noise in the frequency domain reveals a subdiffusion motion of individual adsorbed molecules in the hot-spot. The cutoff frequency between the white and pink noise is used to determine the in-line molecular concentration over a wide range between 10–11 and 10–6 M.

We present a $2\times 2$ hybrid silicon-plasmonic thermooptic (TO) asymmetric Mach–Zehnder interferometric (MZI) switch having only 40- $\mu \text{m}$ long active cyclomer-loaded plasmonic phase arms. It requires less than 12 mW of power and has 2/5- $\mu \text{s}$ ON/OFF-times, respectively, a modulation depth higher than 90% and a 13.2-dB extinction ratio. Data traffic evaluation has been carried out using 10-Gb/s nonreturn-to-zero streams, yielding error-free operation at both switching states with power penalties ranging between 1 to 4.8 dB. The use of the cyclomer loading having a higher TO coefficient than polymethyl methacrylate has resulted to the smallest footprint among plasmonic MZI TO switches reported so far.

Plasmonic technology has attracted intense research interest enhancing the functional portfolio of photonic integrated circuits (PICs) by providing Surface-Plasmon-Polariton (SPP) modes with ultra-high confinement at sub-wavelength scale dimensions and as such increased light matter interaction. However, in most cases plasmonic waveguides rely mainly on noble metals and exhibit high optical losses, impeding their employment in CMOS processes and their practical deployment in highly useful PICs. Hence, merging CMOS compatible plasmonic waveguides with low-loss photonics by judiciously interfacing these two waveguide platforms appears as the most promising route towards the rapid and costefficient manufacturing of high-performance plasmo-photonic integrated circuits. In this work, we present butt-coupled plasmo-photonic interfaces between CMOS compatible 7μm-wide Aluminum (Al) and Copper (Cu) metal stripes and 360×800nm Si3N4 waveguides. The interfaces have been designed by means of 3D FDTD and have been optimized for aqueous environment targeting their future employment in biosensing interferometric arrangements, with the photonic waveguides being cladded with 660nm of Low Temperature Oxide (LTO) and the plasmonic stripes being recessed in a cavity formed between the photonic waveguides. The geometrical parameters of the interface will be presented based on detailed simulation results, using experimentally verified plasmonic properties for the employed CMOS metals. Numerical simulations dictated a coupling efficiency of 53% and 68% at 1.55μm wavelength for Al and Cu, respectively, with the plasmonic propagation length Lspp equaling 66μm for Al and 75μm for Cu with water considered as the top cladding. The proposed interface configuration is currently being fabricated for experimental verification.

We demonstrate a butt-coupled interface between LPCVD Si 3 N 4 and gold based plasmonic waveguides in aqueous environment, exhibiting 2.3dB coupling loss and 75μm propagation length at 1550nm, towards future employment in biosensing applications.

We demonstrate a photonic integrated Mach-Zehnder interferometric sensor, utilizing a plasmonic stripe waveguide in the sensing branch and a photonic variable optical attenuator and a phase shifter in the reference arm to optimize the interferometer operation. The plasmonic sensor is used to detect changes in the refractive index of the surrounding medium exploiting the accumulated phase change of the propagating Surface-Plasmon-Polariton (SPP) mode that is fully exposed in an aqueous buffer solution. The variable optical attenuation stage is incorporated in the reference Si3N4 branch, as the means to counter-balance the optical losses introduced by the plasmonic branch and optimize interference at the sensor output. Bulk sensitivity values of 1930 nm/RIU were experimentally measured for a Mach Zehnder Interferometer (MZI) with a Free Spectral Range of 24.8 nm, along with extinction ratio of more than 35 dB, demonstrating the functional benefits of the co-integration of plasmonic and photonic waveguides.

Slot-based plasmonic waveguides have attracted significant attention owing to their unique ability to confine light within nanometer-scale. In this context, enhanced localized light-matter interaction and control have been exploited to demonstrate novel concepts in data communication and sensing applications revealing the immense potential of plasmonic slot waveguides. However, inherent light absorption in the metallic parts included is such structures hampers the scaling of plasmonic devices and limits their application diversity. A promising solution of such issues is the use of hybrid plasmo-photonic configurations. Hybrid slot waveguides have been introduced as the means to reduce such propagation losses while maintaining their functional advantages. In addition, their co-integration with low-loss photonic waveguides can enable the development of more complex structures with acceptable overall losses. In such scenario, light needs to be efficiently transferred from the photonic to the plasmonic components and/or backwards. Based on this rationale, in this work a hybrid slot-based structure is adopted to achieve highly efficient light transfer between photonic and plasmonic slot waveguides in the near-infrared spectrum region (λ=1550 nm). This transition is realized with the aid of a directional coupling scheme. For this purpose, a Si3N4 bus waveguide (photonic branch) is located below an Aubased metallic slot (plasmonic branch) forming a hybrid waveguide element. The combined configuration, as it is shown with the aid of numerical simulations , is capable of supporting two hybrid guided modes with quasi-even and odd symmetry allowing the development of a power exchange mechanism between the two branches. In this context, a new directional coupling structure has been designed which can achieve power transmission per transition over 68% within a coupling length of the order of just several microns.

The Purcell factor $F_p$ is a key quantity in cavity quantum electrodynamics (cQED) that quantifies the coupling rate between a dipolar emitter and a cavity mode. Its simple form $F_p\propto Q/V$ unravels the possible strategies to enhance and control light-matter interaction. Practically, efficient light-matter interaction is achieved thanks to either i) high quality factor $Q$ at the basis of cQED or ii) low modal volume $V$ at the basis of nanophotonics and plasmonics. In the last decade, strong efforts have been done to derive a plasmonic Purcell factor in order to transpose cQED concepts to the nanocale, in a scale-law approach. In this work, we discuss the plasmonic Purcell factor for both delocalized (SPP) and localized (LSP) surface-plasmon-polaritons and briefly summarize the expected applications for nanophotonics. On the basis of the SPP resonance shape (Lorentzian or Fano profile), we derive closed form expression for the coupling rate to delocalized plasmons. The quality factor factor and modal confinement of both SPP and LSP are quantified, demonstrating their strongly subwavelength behaviour., Comment: Journal of Optics (in press)

Surface enhanced Raman scattering (SERS) spectroscopy becomes increasingly used in biosensors for its capacity to detect and identify single molecules. In practice, a large number of SERS spectra are acquired and reliable ranking methods are thus essential for analysing all these data. Supervised classification strategies, which are the most effective methods, are usually applied but they require pre-determined models or classes. In this work, we propose to sort SERS spectra in unknown groups with an alternative strategy called Fourier polar representation. This non-fitting method based on simple Fourier sine and cosine transforms produces a fast and graphical representation for sorting SERS spectra with quantitative information. The reliability of this method was first investigated theoretically and numerically. Then, its performances were tested on two concrete biological examples: first with single amino-acid molecule (cysteine) and then with a mixture of three distinct odorous molecules. The benefits of this Fourier polar representation were highlighted and compared to the well-established statistical principal component analysis method.

We demonstrate wavelength-division-multiplexed (WDM) 200 Gb/s (8 × 25 Gb/s) data transmission over 100 μm long aluminum (Al) surface-plasmon-polariton (SPP) waveguides on a Si3N4 waveguide platform at telecom wavelengths. The Al SPP waveguide was evaluated in terms of signal integrity by performing bit-error-rate (BER) measurements that revealed error-free operation for all eight 25 Gb/s non-return-to-zero (NRZ) modulated data channels with power penalties not exceeding 0.2 dB at 10−9. To the best of our knowledge, this is the first demonstration of WDM enabled data transmission over complementary-metal-oxide-semiconductor (CMOS) SPP waveguides fueling future development of CMOS compatible plasmo-photonic devices for on-chip optical interconnections.

Display Omitted A lithography technique capable of printing submicron-sized features inside deep cavities is presented.A so-called recess photomask adapted to the wafer's topography is employed.Based on a standard mask aligner, Recess Photomask Contact Lithography has moderate cost.Its efficiency for a photonic/plasmonic switch application was demonstrated experimentally.The technique is extensible to any design and to wafers with multiple level recesses. A novel lithographic method is presented, based on the use of a mask aligner in the contact mode with a modified photomask, the so-called recess photomask; its goal is the printing of submicron-sized patterns into deep cavities of a chip, which is not manageable with conventional contact lithography. The photomask (initially a standard photomask) is etched in designated sections in order to obtain a surface nearly conformal to the topography of the wafer to be patterned and allowing to maintain the ultimate resolution of UV mask aligners in the contact mode, down to ~0.5µm critical dimension at 250nm wavelength in spite of the difficult topography of the chip. The technique is successfully applied to the integration of polymer and gold plasmonic structures in silicon photonic SOI chips with 1.9µm deep cavities intended to accommodate the plasmonic waveguide switching technology. In this specific application, coupling of silicon photonic waveguides with small-footprint plasmonic waveguides can assure ultrafast and low-power electrically-driven thermo-optical switching. The method is generic as it can be applied to any pre-existing resist process and has no theoretical recess depth limit. It is potentially widely applicable to emerging technologies in fields including optoelectronic and integrated optical communications devices, but also potentially MEMS and MOEMS.

Since the 1980s, researchers have been trying to design so-called "optical" computers, in which electrical signals would be replaced by photonic signals. For this, it is necessary to look at interconnection problems between components. This thesis deals with the problem of optical interconnection between electronic components. In order to propose a solution to this problem, we will study two types of plasmonic structures, a first structure of a single solid block where the information wave is reflected on an air prism, this structure is composed of a guide of metal wave covered with a layer of photoresist and it is named "ultra-long-distance plasmonic guide" (ULR-SPP). The second structure is based on a flexible interconnection where the information flows along a flexible guide, this type of wave is called "PlasArc". Through a numerical simulation chapter, we will determine the dimensional characteristics in order to minimize the energy losses by propagation of our waveguides in each of the structures. All our simulations are performed in the waveband of telecom signals. Then, we present the fabrication of two types of plasmonic waveguides as well as their specificities of realization namely a deep etching of 60 μm for ULRSPP structures and the removal of a solid substrate for waveguide named "PlasArc". The characterization of structures will be realized by distinct methods (cut-back, measurements of the loss by propagation along the guide, size of the mode obtained at the end of the guide, ...) on sizes of samples that can go from 5 mm to several centimeters in length. A study of the loss according to the radius of curvature is established on plasmonic waveguides of "PlasArc" type, Depuis les années 1980, les chercheurs essayent de concevoir des ordinateurs dits « optiques », au sein desquels les signaux électriques seraient remplacés par des signaux photoniques. Pour cela, il est nécessaire de s’intéresser aux problèmes d’interconnexions entre les composants. Cette thèse porte sur la problématique de l’interconnexion optique entre composants électroniques. Afin de proposer une solution à cette problématique, nous étudierons deux types de structures plasmoniques, une première structure d’un seul bloc solide où l’onde d’information est réfléchie sur un prisme d’air, cette structure est composée d’un guide d’onde métallique recouverte d’une couche de photoresist et elle est nommée « guide plasmonique à ultra longue distance » (ULR-SPP). La seconde structure est basée sur une interconnexion flexible où l’information circule le longue d’un guide souple, ce type d’onde est qualifié de « PlasArc ». Au travers d’un chapitre de simulation numérique, nous déterminerons les caractéristiques dimensionnelles afin de minimiser les pertes d’énergies par propagations de nos guides d’ondes dans chacune des structures. Toutes nos simulations sont effectuées dans la gamme d’ondes des signaux télécoms. Puis, nous présentons la fabrication de nos deux types de guides d'ondes ainsi que leurs spécificités de réalisation à savoir une gravure profonde sèche de 60 µm pour les structures ULRSPP et le retrait d’un substrat solide pour les guides « PlasArc ». La caractérisation de nos structures seront réalisées par des méthodes distinctes (réduction successive de la longueur des échantillons, mesures de la perte par propagation le long du guide, taille du mode obtenu en bout de guide, …) sur des tailles d’échantillons pouvant aller de 5 mm à plusieurs centimètres de longueurs. Une étude de la perte selon le rayon de courbure est établie sur les guides d’ondes plasmoniques de type « PlasArc »

Surface plasmon polariton (SPP) can confine light on subwavelength dimensions. Since they are not diffraction limited, they are of great interest for addressing and controlling optical nanosources. For example, a metal nanowire defines 1D plasmonic waveguide with a great potential for either addressing or coupling quantum emitters. Therefore, SPP opens great opportunities for integrated optical applications. However, SPP suffer from ohmic losses that jeopardize the applications of plasmonic components. In this context, we study the possibilities provided by an hybrid plasmonic-photonicstructure to couple efficiently an emitter to a fiber mode. Such a structure paves the way for fibered single photon nanosource or high resolution optical probe. In this thesis manuscript, we first study the coupling rate between a fluorescent molecule and a metallic nanowire thanks to Green’s dyad formalism. This leads us to distinguish the different relaxation channels and the enhancement of the energy transferred into the plasmonic guided mode by optimizing the shape of the guide (crystalline nano-wire,slow modes). Then, we investigate the energy propagation in a metal coated taperedoptical fiber. Finally, we achieve an optimal configuration for which more than 50% of the energy emitted by a quantum emitter laid on a substrat is transferred into an optical fiber., Les plasmons polaritons de surface, modes supportés par des nanostructures métalliques permettent de confiner la lumière à des échelles sub-longueurs d’onde. En s’affranchissant de la limite de diffraction, ces modes constituent des pistes intéressantes pour l’adressage et le contrôle de nanosources optiques (molécules, boites quantiques...). Par exemple, un nanofil métallique constitue un guide plasmonique unidimensionnel qui permet d’exciter une nanosource ou encore de coupler deux émetteurs avec des applications possibles pour la réalisation de composants nano-optiques intégrés. En revanche, la perte d’énergie dans le métal diminue la portée de ces dispositifs. Une stratégie consiste donc à travailler sur une configuration hybride : plasmonique et fibre optique, pour coupler efficacement l’émission de la nanosource à un mode de fibre. Ceci ouvre la voie à la réalisation d’une nanosource fibrée de manipulation aisée pouvant être utilisée comme source de photon unique pour la cryptographie quantique ou plus simplement comme une sonde de champ proche optique haute résolution.Après une étude des principaux canaux de relaxation d’une molécule fluorescente à proximité d’un guide plasmonique, nous discutons de l’optimisation du couplage entre l’émetteur et le guide plasmonique en jouant sur sa forme et la longueur d’onde d’émission. Ensuite, nous nous intéressons au comportement d’une structure hybride composée d’une fibre optique étirée et métallisée. Enfin, nous montrons que l’optimisation du transfert d’énergie d’une molécule fluorescente en présence de cette structure permet de collecter plus de 50% de l’énergie lumineuse d’un nano-émetteur posé sur un substrat vers une fibre optique par le truchement d’un plasmon.