Instituto Universitario de Tecnología NanoFotónica

investigadores 29
subvenciones 2.021.540 €
contratación 123.690 €

Principales clientes

LUMENSIA SENSORS, EUROPEAN SPACE AGENCY , DAS PHOTONICS , EUROPEAN DEFENCE AGENCY, HUAWEI TECHNOLOGIES CO., LTD

Líneas I+D+i

  • Biofotónica. Photonic crystal sensors.
    Photonic crystal structures are one class of planar integrated structures that present a forbidden transmission band in their spectrum, known as photonic bandgap (PBG), due to a periodicity in their dielectric distribution. The position of this PBG will be highly dependent of the refractive index of the substances surrounding the structure, thus enabling its use for sensing purposes. But one of the main distinguishing points of these structures for sensing is the appearance of the slow-wave effect, which can lead to a significant increase of the sensitivity. The slow-wave effect produces a spatial compression of the propagated wave, what translates into a higher intensity of the optical field and a longer interaction time, thus leading to an effectively higher sensitivity not achievable using other integrated photonic structures (e.g., ring resonators). Our group has been one of the first groups working in the use of photonic crystal structures for sensing purposes, being to our knowledge the first group reporting ssDNA sensing results using a SOI photonic crystal waveguide. We have obtained these results using sharp fringes appearing in the slow-light regime near the edge of the guided band, whose origin is the Fabry-Perot cavity created in the interfaces between the access waveguides and the photonic crustal structure. The use of these fringes instead of the PBG edge position itself allows us to perform and easier and more accurate tracking of the spectral shift. Additionally, we have also demonstrated how a better sensitivity is obtained as we use spectral features being closer to the PBG edge, where the influence of the slow-wave effect is significantly higher..
  • Biofotónica. Power-based sensing.
    Most of the photonic sensing structures currently used base their detection on the continuous acquisition of the structure¿s transmission/reflection spectrum in order to monitor its spectral shifting, as it occurs for ring resonators or photonic crystals. However, this spectral-based interrogation scheme has two main drawbacks: i) the need for either a tuneable laser or a spectrometer, which are expensive (typically costing several tens of kEuros), bulky and heavy instruments, and ii) the inability to achieve true real-time detection, since a sweeping time of several seconds or even minutes is required to obtain each spectrum. Our group has proposed and patented a novel power-based sensing approach that overcomes these drawbacks. This approach is based in the use of PBG sensing structures, whose spectral shift is indirectly measured by simply exciting the photonic sensor with a filtered broadband source, which will be located in the wavelength range of one edge of the sensor¿s PBG, and measuring the output power simply using a photodetector. In this way, the output power, given by the overlap between the responses of the source and the sensor, will directly continuously provide the sensing information in real-time without the need to obtain the structure¿s response using tuneable elements. We have experimentally demonstrated this sensing technique for the detection of refractive index variations and antibody sensing using integrated planar PBG sensing structures in silicon. Preliminary results obtained using this sensing technique showed a refractive index detection limit of ~10-6 RIU (Refractive Index Units) and a concentration detection limit below 10 ng/ml for antibody detection.
  • Biofotónica. Ring resonator sensors.
    Probably the main nanophotonic structure used for the development of biosensing devices is the ring resonator. In this structure, very sharp and defined spectral features are obtained, what eases their tracking in order to perform the sensing. Our group has also worked in the development of this type of sensing elements. Some of the work carried out by our group has been focused on the development of silicon ring resonator sensors for the specific detection of single stranded DNA (e.g., for bacteria identification, as done in the frame of the FP7-INTOPSENS project). We have been able to develop several experimental protocols leading to the specific detection of ssDNA with detection limits in the nM range. The development of these sensing protocols, which has been carried out in collaboration with the "Signal and Measurement in Chemistry" group at our university, has been focused on achieving an immobilization approach where crosslinkers are not required, thus leading to a higher proximity of the capture probes and the sensing structure for a higher sensitivity..
  • Fotovoltaica. Fotovoltaica.
    Desarrollo de tecnología de células de Silicio cristalino de alta eficiencia para transferencia a la industria fotovoltaica. Desarrollo de tecnología de capa fina de Silicio amorfo para transferencia a la Industria. Investigación de nanotecnología y nanofotónica aplicados a la fotovoltaica.
  • Metamateriales plasmónicos. Metamaterials.
    The prefix meta-, from the Greek ¿¿¿¿, "beyond" is used to refer to a new type of device: metamerials. They may be defined as those materials or artificial devices, i.e. man-made, that have unusual electromagnetic properties not achievable by natural media and come from the designed structure and not its composition. Metamaterials are of great importance in electromagnetism as they allow us to obtain materials with an adjustable refractive index, being able to obtain the most striking negative refractive indices, creating superlenses, which dramatically improve the quality of images, and securing means to obtain media with unusual or extreme constitutive parameters. Many applications can be achieved with metamaterials, such as modulators, filters, lenses, couplers and antennas. We have been working in the design of devices with negative index. In this regard, several designs have been proposed and characterized thus obtaining a low loss negative index at optical frequencies. Another line of research focuses on the design of structures with artificial magnetic activity in the visible range..
  • Metamateriales plasmónicos. Nanoantennas.
    Optical nanoantennas efficiently convert confined optical energy into free-space radiation. Although plasmonic nanoantennas typically make use of fields confined in dimensions much smaller than the light wavelength, there exists also the possibility to use guided waves in low-loss waveguides. This way, optical nanoantennas would become completely identical to their RF counterpart. Typically, the optical nanoantennas considered so far generate linearly-polarized fields with the electric field confined along the nanoantenna plane. Within this activity, we have been designing optical nanoantennas fed by silicon waveguides in order to generate and detect complex polarization states, such as circular or even elliptical polarization..
  • Metamateriales plasmónicos. Optomechanics.
    The simultaneous confinement and enhanced interaction of photons and phonons in periodic nanostructures has become a hot-topic in recent years giving rise to the field known as optomechanics. We employ photonic crystals(PCSs) built on suspended-silicon slabs as periodic optomechanical nanostructures to check the interaction between light and sound at the nanoscale. PCSs consist of a periodic lattice of holes perforating a high-index semiconductor film so that light confinement in the film is achieved and the periodicity gives rise to bandgaps to forbid guided-light propagation. The introduction of line defects in PCSs has become a powerful way to create light waveguides at the nanoscale with some special properties such as lossless sharp bending or slow-light propagation. Some studies show that square- and honeycomb-lattice suspended PCSs possess bandgaps as much for photons as for acoustic waves. If such PCSs are designed to present bandgaps for guided photons at optical communication wavelengths, bandgaps for phonons appear at frequencies of some gigahertzes. Therefore, these structures can become an important platform for optomechanics as well as for demonstration of other interesting acousto-optical effects such as stimulated Brillouin scattering at the nanoscale..
  • Metamateriales plasmónicos. Plasmonics.
    The term plasmonics comes from concept of surface plasmon polariton, commonly referred to as plasmon, which is a kind of surface wave propagating at the interface between a metal and a dielectric due to the collective oscillation of the electrons to incident electromagnetic radiation. This kind of excitation is the main cause of the phenomenon of extraordinary transmission (EOT) across thin metallic hole arrays, which allows their use as wavelength-selective elements. Plasmons are also behind the response at optical wavelengths of the meta-atoms forming metamaterials. However, its application goes beyond, and also includes the design of certain optical metamaterials as their electromagnetic behavior is linked to the plasmon excitation. Multiple applications venture into the field of plasmonics due to the physical characteristics that plasmons present. Thus, their reduced wavelength allows their use in high resolution technologies such as lithography and microscopy. Moreover, its ability to confine the light in very small dimensions together with their sensitivity to material properties over they propagate, postulate them as promising candidates in ultrasensitive sensors. Our research has yielded ultra-compact filtering structures based on the phenomenon of the EOT. We have also designed and characterized plasmonic nanostructures for biosensing applications. Finally, we have been able to show a way to unidirectional launching of surface plasmons by using circularly polarized light..
  • Metamateriales plasmónicos. Trasnformation Optics.
    This new method uses differential-geometric techniques to find out the properties that a medium should have in order to curve or distort electromagnetic space in almost any desired way. It has made it possible to build devices such as invisibility cloaks or optical black holes. Our work includes the development and application of design methodologies that simplify the optical properties required to synthesize transformation-optics-based devices (e.g. quasi-conformal mappings). Moreover, we have designed devices with unusual properties such as flat reflectionless squeezers and hyperlenses, special radiation-pattern-shaping devices, and light-surface plasmon polariton couplers with increased angular bandwidths. In addition, we are working on the extension of the full possibilities brought about by transformation optics to other fields of physics.
  • Modulador óptico. Fiber-to-chip coupling.
    One of the key issues for bringing silicon photonics research to market is to efficiently solve the problem of coupling light in and out of the silicon integrated circuit together with an efficient and low cost packaging solution. In this context, we have developed and demonstrated a cost effective and smart solution for low profile packaging of silicon photonic integrated circuits with multiple grating-based optical interfaces. Gratings couplers offer clear advantages compared to lateral coupling, such as compatibility with planar processing, the possibility for wafer-level testing, and relatively large alignment tolerances. However, gratings also evoke the need for entirely new smart packaging solutions due to the effect of out-of-plane coupling. In our approach, a sub-mount carrier is proposed to maintain the standard horizontal orientation of the fibers in the package while holding the silicon circuits perpendicularly to the fibers. The carrier offers also flexibility to implement the electrical connectivity in case of handling both optical and electrical pin-out, for instance with use of a flexible wiring layer in between the carrier and photonic and electronics circuits..
  • Modulador óptico. Silicon Transceivers.
    An ever growing amount of access network bandwidth is required by end users, and the deployment of passive optical networks, operating at up to 10 Gbit/s has already begun to address this demand. DQPSK modulation is a promising modulation format for scaling the bit rate at low cost while keeping the legacy 10 GHz devices. We have demonstrated a silicon differential receiver for DQPSK demodulation operating up to 20Gb/s. The receiver integrates a tunable power splitter, a delay-line spiral, a compact 2x4 multimode interference 90 degree hybrid and two balanced germanium photodetectors. Each building block of the receiver was optimized for high performance, low loss and maximum compactness. We use zero bias balanced detection to achieve a 3dB increase in sensitivity as well as scaling down the complexity and size of the receiver. A high-speed differential phase shift keying (DPSK) modulation using a silicon push-pull operated dual-drive Mach Zehnder modulator (MZM) based on carrier depletion has also experimentally demostrated. Up to 10 Gbit/s error-free modulation (BER<10-9) with no error floor was measured. Furthermore, the potential for higher DPSK modulation speeds up to 20 Gbit/s was also demonstrated.
  • Modulador óptico. Silicon plasmonic rotator.
    Polarization management is a key issue in a lot of applications in photonics. One example is the development of receivers for optical communications systems. As the state of polarization changes randomly in the optical fiber, it is necessary to control the polarization at the receiver side. Polarization diversity schemes, usually based on polarization splitters and rotators, allow the receiver to operate independently of the input polarization. Polarization circuits, and in particular rotators, have been largely studied and demonstrated in silicon photonics. A silicon rotator based on symmetry breaking of the waveguide cross section was proposed and demonstrated by our group in collaboration with Ghent University and DAS Photonics. The 25 µm-long rotator was fabricated in CEA-Leti using standard CMOS processes and exhibited a polarization conversion efficiency above -0.85 dB with insertion losses ranging from -1 dB to -2.5 dB over a wavelength range of 30 nm. In recent times there have been developed new topologies based on hybrid silicon plasmonic structures to drastically reduce the dimensions of the rotators. In this context, a novel ultra-compact (8 µm length) hybrid silicon-plasmonic TM-TE converter has been proposed by our group. The conversion was achieved during a partial power coupling between a waveguide and a hybrid plasmonic parallel waveguide. At a wavelength of 1.55 µm, an extinction ratio of 27.6 dB and insertion losses of 1.75 dB was achieved. Furthermore, an optical bandwidth as large as 100 nm was obtained with extinction ratios higher than 25 dB and insertion losses below 2 dB..
  • Modulador óptico. Slow-wave modulator.
    In the context of an ever increasing demand for bandwidth, handling electrical-to-optical data conversion through compact and high speed electro-optical modulators is of paramount importance. To tackle these challenges, we exploit the attractive properties of slow light propagation to demonstrate a highly efficient and mass-manufacturable 500 µm-long carrier-depletion silicon modulator device capable of transmitting digital data up to 40 Gbit/s with moderate insertion losses. The enhanced light-matter interaction enabled a modulation efficiency up to 8 times greater than that of a conventional rib modulator (V¿L¿ ~0.45 V.cm). The obtained results position our slow light modulator amongst the state-of-the-art of current silicon modulators. A low power version of the slow-wave modulator was also demonstrated showing up to 10Gb/s transmission with 1.5 Vpp driving voltage.
  • Nanofotónica para Microondas. Nanofotónica en Grafeno.
  • Nanofotónica para Microondas. Nanofotónica para Microondas.
  • Nanofotónica para Microondas. Nanosistemas Fotónicos.
  • Nanofotónica para Microondas. Procesado Nanofotónico de la Señal.
  • Sistemas y Redes Ópticas. Acceso Óptico y Redes de Nueva Generación.
    El Área de Acceso Óptico y Redes de Nueva Generación investiga arquitecturas y tecnologías para la red de acceso basadas en fibra óptica (FTTH, fibre-to-the-home) capaces de proporcionar altos regímenes binarios (superiores a decenas de Gigabit/s por usuario) en una gran zona geográfica de la manera más económica posible en cuanto a despliegue, operación, mantenimiento y consumo energético. Esta área también investiga arquitecturas híbridas radio- fibra óptica capaces de proveer un alto régimen binario vía radio-frecuencia junto a la conectividad óptica para usuarios en movilidad, tanto en redes de acceso como en instalaciones en edificios. Estas arquitecturas utilizan las últimas tecnologías como radio de banda ultra-ancha (UWB, ultra-wideband), WiMAX o LTE entre otras. Distintas técnicas para aumentar la capacidad de la red óptica, como multiplexación en sub-portadoras (SCM, sub-carrier multiplexing), multiplexación división por división en longitud de onda (DWMD, dense wavelength división multiplexing), o multiplexación en polarización (PDM, polarization-division multiplexing) son también investigadas. Arquitecturas de red tipo red óptica pasiva (PON, passive optical networks) y también en redes de acceso con secciones de amplificación son consideradas, así como nuevos esquemas de generación de señal y de modulación. Técnicas novedosas para mitigar los principales factores limitantes de la transmisión óptica, como la dispersión modal por polarización (PMD, polarization-mode dispersión) en fibras mono-modo, o la dispersión modal (MMD, multi-mode dispersion) en fibras multi-modo son también investigadas en esta línea de investigación..
  • Sistemas y Redes Ópticas. Conformación óptica de haces para agrupaciones de antenas.
    El elevado producto tiempo-ancho de banda de los componentes ópticos permite controlar las agrupaciones de antenas sin los problemas de las implementaciones puramente electrónicas. Los componentes ópticos permiten obtener retardo verdadero (con lo que desaparece el problema del beam squint en antenas de gran ancho de banda), integración con sistemas de alimentación remota de antenas y flexibilidad en antenas desplegables..
  • Sistemas y Redes Ópticas. Espectroscopía de THz en fibra óptica. .
    La espectroscopía de THz basada en antenas fotoconductivas es una herramienta de sensado que proporciona información única. Entre los 100 GHz y 10 THz se producen interacciones complejas entre radiación y material que pueden aprovecharse para conseguir innovadores sistemas de sensado e imaging. La banda de los THz permite trabajar con señales de enorme ancho de banda, son no-ionizantes y muchos materiales que son opacos en el espectro visible e infrarrojo son transparentes en esta banda. Otros materiales presentan huellas espectrales distintivas en esta región lo cual es muy útil en campos como biología, medicina, monitorización de procesos industriales, seguridad, comunicaciones, inspección no destructiva, etc..
  • Sistemas y Redes Ópticas. Procesado óptico de señales de microondas.
    Los sistemas ópticos ofrecen anchos de banda elevados que pueden aprovecharse para generar, filtrar y reconfigurar señales de microondas evitando las limitaciones de los dispositivos electrónicos. Estos esquemas también se pueden combinar con redes de distribución radio-sobre-fibra.
  • Sistemas y Redes Ópticas. Técnicas fotónicas para la medida de señales de microondas.
    Mediante el uso de componentes y esquemas basados en fibra óptica es posible desarrollar esquemas para extender las capacidades de la instrumentación de microondas en términos de ancho de banda, velocidad de medida, etc..

Infraestructuras relevantes

  • Sala limpia (500 m2 clase 10-100-10000) Caracterización física (SEM, AFM, Perfilómetro) Caracterización óptica (FTIR, ADF, Medida de índice de refracción) Caracterización eléctrica (IV, EQE/IQE, Lifetime, Resistencia de hoja y contacto)