Guide d’onda cristalline in BaY2F8 drogato con Er3+ per amplificazione ottica su larga banda

Lo scopo di questo lavoro di tesi è stato quello di mostrare la possibilità di realizzare amplificatori integrati in guide ottiche utilizzando cristalli drogati con terre rare. Il principio sul quale si basa l’amplificazione ottica di segnali di comunicazione è lo stesso che regola il funzionamento dei laser. La banda spettrale utilizzata commercialmente per comunicazioni ottiche WDM , è compresa fra 1530nm ed i 1610nm. Lo ione Erbio, quale drogante in materiali vetrosi consente di ottenere amplificazione ottica su tale banda che coincide inoltre con il minimo dell’attenuazione delle fibre monomodo di trasmissione, ed è quindi la terra rara più diffusa come drogante negli amplificatori ottici. Dispostivi commerciali per amplificazione ottica utilizzano fibre ottiche in silica drogata con Erbio e consentono di ottenere amplificazione su una banda di qualche decina di nm. La formazione di cluster di ioni Er3+ nel materiale vetroso ad elevate concentrazioni dà luogo a fenomeni di interazione fra ioni, limita dunque il livello di massimo di drogaggio utilizzabile e non consente l’integrazione dell’amplificatore ottico. L’interazione fra ioni di Erbio nel materiale è uno dei principali fattori limitanti per il coefficiente di guadagno che caratterizza l’amplificatore. Il principale vantaggio dell’uso di un materiale cristallino come ospite per gli ioni droganti è quello di evitare la formazione di coppie (o gruppi più numerosi) di ioni interagenti, permettendo quindi un drogaggio più elevato e quindi la possibile integrazione dell’amplificatore. Inoltre materiali cristallini drogati con terre rare consentono amplificazione su una banda più larga rispetto al caso di materiali vetrosi (fino a 100 nm contro i 30-40 nm nel caso di vetri). In questa tesi proponiamo dunque la caratterizzazione sperimentale di materiali cristallini drogati con Erbio ed il loro impiego nel progetto di amplificatori ottici in guida a larga banda. Per valutare questa possibilità è stato studiato il cristallo di BaY2F8 (BaYF). In un primo tempo è stato svolto uno studio sperimentale spettroscopico dell’Erbio in questo cristallo, che ci ha permesso di ricavarne alcune proprietà fondamentali quali i tempi di vita media dei livelli di interesse per l’amplificazione e la sezione d’urto spettrale di assorbimento. Per completare la caratterizzazione del cristallo sono state svolte misure di fluorescenza a temperatura ambiente nella banda compresa fra 1450nm e 1650nm e nelle 6 diverse possibili polarizzazioni di campo elettromagnetico. Successivamente è stata calcolata la sezione d’urto spettrale di emissione tramite il metodo della reciprocità partendo dalla sezione d’urto di assorbimento. E’ stato inoltre sviluppato un modello teorico in grado di fornire le caratteristiche principali di un amplificatore ottico in guida (guadagno, figura di rumore, potenza del segnale in uscita, etc), utilizzando come input parametri fisici del materiale individuati sperimentalmente mediante misure spettroscopiche. Il modello utilizza il metodo degli elementi finiti (FEM) per l’analisi elettromagnetica della guida, ed è basatosu equazioni di propagazione per individuare l’evoluzione longitudinale delle potenza di pompa, segnale e rumore ottico corrispondente all’ASE (Amplified Spontaneous Emission) lungo la guida. Queste equazioni vengono utilzzate in combinazione con le equazioni di rate che descrivono la popolazione dei vari multipletti dell’Erbio nel BaYF. Come prima approssimazione abbiamo assunto un sistema a tre livelli, 4I15/2, 4I13/2e 4I11/2 in cui viene eccitata la transizione 4I15/2®4I13/2, alla lunghezza d’onda di 1480nm. Le equazioni di propagazione sono risolte numericamente combinando il FEM con un algoritmo di Runge-Kutta al quarto ordine, e tengono conto di schemi di pompaggio co- e contropropagante, segnali WDM e della distribuzione spettrale dell’ASE in entrambe le direzioni di propagazione. Inanzitutto abbiamo studiato le caratteristiche di guadagno spettrale della guida, e trovato la lunghezza d’onda di guadagno massimo, poi abbiamo studiato l’effetto di un aumento della concentrazione di ioni droganti sul coefficiente di guadagno e sulla figura di rumore dell’amplificatore, trovando la concentrazione di Erbio ottimale. Mantenendo questa concentrazione fissata abbiamo poi studiato il guadagno in funzione della lunghezza della guida, della potenza di pompa e la curva di saturazione dell’amplificatore, cioè la curva di guadagno in funzione della potenza d’ingresso del segnale. Infine abbiamo simulato l’amplificazione contemporanea di più canali WDM. I risultati delle simulazioni mostrano che la concentrazione di Erbio ottimale nel BaYF, NErOtt=3.4x1026 ioni/m3, è molto più elevata di quanto non sia nei vetri (tipicamente si hanno concentrazione di un ordine di grandezza in meno). Inoltre è possibile ottenere amplificazione su una banda di oltre 80nm, con valore di picco di oltre 2dB/cm, mentre nei vetri drogati esclusivamente con Erbio i valori tipici di guadagno massimo sono dell’ordine di 1dB/cm e le bande di guadagno limitate a circa 30-40 nm. Abbiamo dunque mostrato la possibilità di amplificare segnali ottici con guide cristalline, ed i vantaggi apportati dai cristalli rispetto ai vetri in termini di concentrazione di ioni droganti, banda di amplificazione e coefficiente di guadagno

Real-Time and Low-Cost Sensing Technique Based on Photonic Bandgap Structures

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.36.002707. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] A technique for the development of low-cost and high-sensitivity photonic biosensing devices is proposed and experimentally demonstrated. In this technique, a photonic bandgap structure is used as transducer, but its readout is performed by simply using a broadband source, an optical filter, and a power meter, without the need of obtaining the transmission spectrum of the structure; thus, a really low-cost system and real-time results are achieved. Experimental results show that it is possible to detect very low refractive index variations, achieving a detection limit below 2 x 10(-6) refractive index units using this low-cost measuring technique. (C) 2011 Optical Society of America[This work was funded by the Spanish Ministerio de Ciencia e Innovacion (MICINN) under contracts TEC2008-06333, JCI-009-5805, and TEC2008-05490. Support by the Universidad Politecnica de Valencia through program PAID-06-09 and the Conselleria d'Educacio through program GV-2010-031 is acknowledged.García Castelló, J.; Toccafondo, V.; Pérez Millán, P.; Sánchez Losilla, N.; Cruz, JL.; Andres, MV.; García-Rupérez, J. (2011). Real-Time and Low-Cost Sensing Technique Based on Photonic Bandgap Structures. Optics Letters. 36(14):2707-2709. https://doi.org/10.1364/OL.36.002707S270727093614Fan, X., White, I. M., Shopova, S. I., Zhu, H., Suter, J. D., & Sun, Y. (2008). Sensitive optical biosensors for unlabeled targets: A review. Analytica Chimica Acta, 620(1-2), 8-26. doi:10.1016/j.aca.2008.05.022Homola, J., Yee, S. S., & Gauglitz, G. (1999). Surface plasmon resonance sensors: review. Sensors and Actuators B: Chemical, 54(1-2), 3-15. doi:10.1016/s0925-4005(98)00321-9Kersey, A. D., Davis, M. A., Patrick, H. J., LeBlanc, M., Koo, K. P., Askins, C. G., … Friebele, E. J. (1997). Fiber grating sensors. Journal of Lightwave Technology, 15(8), 1442-1463. doi:10.1109/50.618377De Vos, K., Bartolozzi, I., Schacht, E., Bienstman, P., & Baets, R. (2007). Silicon-on-Insulator microring resonator for sensitive and label-free biosensing. Optics Express, 15(12), 7610. doi:10.1364/oe.15.007610Iqbal, M., Gleeson, M. A., Spaugh, B., Tybor, F., Gunn, W. G., Hochberg, M., … Gunn, L. C. (2010). Label-Free Biosensor Arrays Based on Silicon Ring Resonators and High-Speed Optical Scanning Instrumentation. IEEE Journal of Selected Topics in Quantum Electronics, 16(3), 654-661. doi:10.1109/jstqe.2009.2032510Xu, D.-X., Vachon, M., Densmore, A., Ma, R., Delâge, A., Janz, S., … Schmid, J. H. (2010). Label-free biosensor array based on silicon-on-insulator ring resonators addressed using a WDM approach. Optics Letters, 35(16), 2771. doi:10.1364/ol.35.002771Skivesen, N., Têtu, A., Kristensen, M., Kjems, J., Frandsen, L. H., & Borel, P. I. (2007). Photonic-crystal waveguide biosensor. Optics Express, 15(6), 3169. doi:10.1364/oe.15.003169Lee, M. R., & Fauchet, P. M. (2007). Nanoscale microcavity sensor for single particle detection. Optics Letters, 32(22), 3284. doi:10.1364/ol.32.003284García-Rupérez, J., Toccafondo, V., Bañuls, M. J., Castelló, J. G., Griol, A., Peransi-Llopis, S., & Maquieira, Á. (2010). Label-free antibody detection using band edge fringes in SOI planar photonic crystal waveguides in the slow-light regime. Optics Express, 18(23), 24276. doi:10.1364/oe.18.024276Toccafondo, V., García-Rupérez, J., Bañuls, M. J., Griol, A., Castelló, J. G., Peransi-Llopis, S., & Maquieira, A. (2010). Single-strand DNA detection using a planar photonic-crystal-waveguide-based sensor. Optics Letters, 35(21), 3673. doi:10.1364/ol.35.003673Luff, B. J., Wilson, R., Schiffrin, D. J., Harris, R. D., & Wilkinson, J. S. (1996). Integrated-optical directional coupler biosensor. Optics Letters, 21(8), 618. doi:10.1364/ol.21.000618Sepúlveda, B., Río, J. S. del, Moreno, M., Blanco, F. J., Mayora, K., Domínguez, C., & Lechuga, L. M. (2006). Optical biosensor microsystems based on the integration of highly sensitive Mach–Zehnder interferometer devices. Journal of Optics A: Pure and Applied Optics, 8(7), S561-S566. doi:10.1088/1464-4258/8/7/s41Densmore, A., Vachon, M., Xu, D.-X., Janz, S., Ma, R., Li, Y.-H., … Schmid, J. H. (2009). Silicon photonic wire biosensor array for multiplexed real-time and label-free molecular detection. Optics Letters, 34(23), 3598. doi:10.1364/ol.34.003598Povinelli, M. L., Johnson, S. G., & Joannopoulos, J. D. (2005). Slow-light, band-edge waveguides for tunable time delays. Optics Express, 13(18), 7145. doi:10.1364/opex.13.007145Garcia, J., Sanchis, P., Martinez, A., & Marti, J. (2008). 1D periodic structures for slow-wave induced non-linearity enhancement. Optics Express, 16(5), 3146. doi:10.1364/oe.16.003146Pérez-Millán, P., Torres-Peiró, S., Cruz, J. L., & Andrés, M. V. (2008). Fabrication of chirped fiber Bragg gratings by simple combination of stretching movements. Optical Fiber Technology, 14(1), 49-53. doi:10.1016/j.yofte.2007.07.00

The Orbital Angular Momentum of Light for Ultra-High Capacity Data Centers

The potential of orbital angular momentum (OAM) of light in data center scenarios is presented. OAMs can be exploited for short reach ultra-high bit rate fiber links and as additional multiplexing domain in transparent ultra-high capacity optical switches. Recent advances on OAM integrated photonic technology are also reported. Finally demonstration of OAM-based fiber links (aggregate throughput 17.9 Tb/s) and two layers OAM-WDM-based optical switches are presented exploiting OAM integrated components and demonstrating the achievable benefits in terms of size, weight and power consumption (SWaP) compared to different technologies

Real-time observation of antigen¿antibody association using a low-cost biosensing system based on photonic bandgap structures

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.37.003684. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] In this letter, we present experimental results of antibody detection using a biosensor based on photonic bandgap structures, which are interrogated using a power-based readout technique. This interrogation method allows a realtime monitoring of the association process between the antigen probes and the target antibodies, allowing the instantaneous observation of any interaction event between molecules. because etunable lasers and optical spectrum analyzers are avoided for the readout, a drastic reduction of the final cost of the platform is obtained. Furthermore, the performance of the biosensing system is significantly enhanced due to the large number of data values obtained per second.This work was partially funded by the European Commission under contract FP7-295043-BELERA, from the Spanish Ministerio de Ciencia e Innovacion (MICINN) under contracts TEC2008-06333 and CTQ2010-15943 (subprogram BQU), and from Generalitat Valenciana through the PROMETEO grants 2010-008 and 2012-087.García Castelló, J.; Toccafondo, V.; Escorihuela Fuentes, J.; Bañuls Polo, MJ.; Maquieira Catala, Á.; García-Rupérez, J. (2012). Real-time observation of antigen¿antibody association using a low-cost biosensing system based on photonic bandgap structures. Optics Letters. 37(17):3684-3686. https://doi.org/10.1364/OL.37.003684S368436863717Luchansky, M. S., & Bailey, R. C. (2011). High-Q Optical Sensors for Chemical and Biological Analysis. Analytical Chemistry, 84(2), 793-821. doi:10.1021/ac2029024Qavi, A. J., & Bailey, R. C. (2010). Multiplexed Detection and Label-Free Quantitation of MicroRNAs Using Arrays of Silicon Photonic Microring Resonators. Angewandte Chemie International Edition, 49(27), 4608-4611. doi:10.1002/anie.201001712García-Rupérez, J., Toccafondo, V., Bañuls, M. J., Castelló, J. G., Griol, A., Peransi-Llopis, S., & Maquieira, Á. (2010). Label-free antibody detection using band edge fringes in SOI planar photonic crystal waveguides in the slow-light regime. Optics Express, 18(23), 24276. doi:10.1364/oe.18.024276Toccafondo, V., García-Rupérez, J., Bañuls, M. J., Griol, A., Castelló, J. G., Peransi-Llopis, S., & Maquieira, A. (2010). Single-strand DNA detection using a planar photonic-crystal-waveguide-based sensor. Optics Letters, 35(21), 3673. doi:10.1364/ol.35.003673Claes, T., Molera, J. G., De Vos, K., Schacht, E., Baets, R., & Bienstman, P. (2009). Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator. IEEE Photonics Journal, 1(3), 197-204. doi:10.1109/jphot.2009.2031596Scullion, M. G., Di Falco, A., & Krauss, T. F. (2011). Slotted photonic crystal cavities with integrated microfluidics for biosensing applications. Biosensors and Bioelectronics, 27(1), 101-105. doi:10.1016/j.bios.2011.06.023Zlatanovic, S., Mirkarimi, L. W., Sigalas, M. M., Bynum, M. A., Chow, E., Robotti, K. M., … Grot, A. (2009). Photonic crystal microcavity sensor for ultracompact monitoring of reaction kinetics and protein concentration. Sensors and Actuators B: Chemical, 141(1), 13-19. doi:10.1016/j.snb.2009.06.007Sepúlveda, B., Río, J. S. del, Moreno, M., Blanco, F. J., Mayora, K., Domínguez, C., & Lechuga, L. M. (2006). Optical biosensor microsystems based on the integration of highly sensitive Mach–Zehnder interferometer devices. Journal of Optics A: Pure and Applied Optics, 8(7), S561-S566. doi:10.1088/1464-4258/8/7/s41Claes, T., Bogaerts, W., & Bienstman, P. (2011). Vernier-cascade label-free biosensor with integrated arrayed waveguide grating for wavelength interrogation with low-cost broadband source. Optics Letters, 36(17), 3320. doi:10.1364/ol.36.003320Zinoviev, K. E., Gonzalez-Guerrero, A. B., Dominguez, C., & Lechuga, L. M. (2011). Integrated Bimodal Waveguide Interferometric Biosensor for Label-Free Analysis. Journal of Lightwave Technology, 29(13), 1926-1930. doi:10.1109/jlt.2011.2150734Densmore, A., Vachon, M., Xu, D.-X., Janz, S., Ma, R., Li, Y.-H., … Schmid, J. H. (2009). Silicon photonic wire biosensor array for multiplexed real-time and label-free molecular detection. Optics Letters, 34(23), 3598. doi:10.1364/ol.34.003598Castelló, J. G., Toccafondo, V., Pérez-Millán, P., Losilla, N. S., Cruz, J. L., Andrés, M. V., & García-Rupérez, J. (2011). Real-time and low-cost sensing technique based on photonic bandgap structures. Optics Letters, 36(14), 2707. doi:10.1364/ol.36.002707Krishnamoorthy, G., Bianca Beusink, J., & Schasfoort, R. B. M. (2010). High-throughput surface plasmon resonance imaging-based biomolecular kinetic screening analysis. Analytical Methods, 2(8), 1020. doi:10.1039/c0ay00112

High sensitivity and label-free oligonucleotides detection using photonic bandgap sensing structures biofunctionalized with molecular beacon probes

A label-free sensor, based on the combination of silicon photonic bandgap (PBG) structures with immobilized molecular beacon (MB) probes, is experimentally developed. Complementary target oligonucleotides are specifically recognized through hybridization with the MB probes on the surface of the sensing structure. This combination of PBG sensing structures and MB probes demonstrates an extremely high sensitivity without the need for complex PCR-based amplification or labelling methods

10 OAM × 16 Wavelengths Two-Layer Switch Based on an Integrated Mode Multiplexer for 19.2 Tb/s Data Traffic

A two-layer switch exploiting orbital angular momentum (OAM) and wavelength of the light as switching domains is presented, aiming to increase the scalability with respect to the single-layer switches. The switch is able to accept 160 optical Gaussian data inputs on a 16-channel wavelength division multiplexing (WDM) grid and direct each input signals to different output ports exploiting 10 OAMs. The optical switch is based on an integrated OAM multiplexer followed by a compact OAM demultiplexer consisting of two refractive elements. Its experimental characterization confirmed a total enabled throughput of 19.2 Tb/s, thanks to the 30 GHz bandwidth available for each port. The switching time can be lower than 1 μs. The OAM switch power consumption, solely due to the thermal tuning of the OAM emitters, since the OAM demux is passive, is 1.35 mW/Gb/s. In the proposed switching architecture the number of active components, i.e., the power consumption, scales linear with the number of ports. This is favorable in comparison with single-layer switches that cascade e.g., 2 × 2 elementary blocks to obtain large port counts, which scale with the square of the number of ports. The switch accepts input and output signals with Gaussian phase profile that propagate through optical fibers and waveguides, thus making it compatible with standard telecom devices. The suitability of the switch to support real data-traffic is proved by successfully testing it with 10G Ethernet and fiber channel over Ethernet (FCoE) data and video traffic. A possible application scenario is represented by a data-center network where the switch can be used to create a low-power consumption network parallel to the network based on standard electronic routers, to manage large traffic flows

Label-Free Optical Single-Molecule Micro- and Nanosensors

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordLabel-free optical sensor systems have emerged that exhibit extraordinary sensitivity for detecting physical, chemical, and biological entities at the micro/nanoscale. Particularly exciting is the detection and analysis of molecules, on miniature optical devices that have many possible applications in health, environment, and security. These micro- and nanosensors have now reached a sensitivity level that allows for the detection and analysis of even single molecules. Their small size enables an exceedingly high sensitivity, and the application of quantum optical measurement techniques can allow the classical limits of detection to be approached or surpassed. The new class of label-free micro- and nanosensors allows dynamic processes at the single-molecule level to be observed directly with light. By virtue of their small interaction length, these micro- and nanosensors probe light–matter interactions over a dynamic range often inaccessible by other optical techniques. For researchers entering this rapidly advancing field of single-molecule micro- and nanosensors, there is an urgent need for a timely review that covers the most recent developments and that identifies the most exciting opportunities. The focus here is to provide a summary of the recent techniques that have either demonstrated label-free single-molecule detection or claim single-molecule sensitivity.Living Systems Institute, University of Exete

Distributed Optical Fiber Radiation and Temperature Sensing at High Energy Accelerators and Experiments

The aim of this Thesis is to investigate the feasibility of a distributed optical fiber radiation sensing system to be used at high energy physics accelerators and experiments where complex mixed-field environments are present. In particular, after having characterized the response of a selection of radiation sensitive optical fibers to ionizing radiation coming from a 60Co source, the results of distributed optical fiber radiation measurements in a mixed-field environment are presented along with the method to actually estimate the dose variation. This study demonstrates that distributed optical fiber dosimetry in the above mentioned mixed-field radiation environment is feasible, allowing to detect dose variations of about 10-15 Gy with a 1 m spatial resolution. The proof of principle has fully succeeded and we can now tackle the challenge of an industrial installation taking into account that some optimizations need to be done both on the control unit of the system as well as on the choice of the sensing fiber. Raman-based optical fiber distributed temperature measurements in a mixed-field environment have also been successfully investigated and are presented in this Thesis work