Wireless body sensor networks for health-monitoring applications

This is an author-created, un-copyedited version of an article accepted for publication in Physiological Measurement. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0967-3334/29/11/R01

Experimental characterization of CMOS photonic devices

Current electrical interconnects in super-computers and high-performance processors present a bottleneck in terms of bandwidth and power consumption. A migration to the optical domain in order to cope with the connectivity between units (e.g. CPUs and memory) is needed to overcome these issues. Zero-change CMOS photonic devices represent a very attractive solution to the design of optical on-chip links. This approach makes use of up-to-date CMOS process, having enormous benefits regarding integration with state-of-the-art electronics. Designing and characterizing zero-change CMOS photonic devices is key for the future of optical interconnects. This thesis presents the characterization both theoretical and experimental of a Silicon-Germanium ring resonator modulator. It represents the first ever depletion modulator up to the date using SiGe as an active material. Moreover, it shows the best wavelength shift reported so far for zero-change CMOS modulators, enhancing the shift of a pure Silicon device. The demonstration of this device begins a new era of optical modulator designs using silicon-germanium to enhance modulation efficiency, and therefore reduce power consumption.Las interconexiones eléctricas de supercomputadores y de microprocesadores de alto rendimiento representan actualmente un bottleneck en cuanto a ancho de banda y potencia consumida se refiere. Se necesita una migración hacia el dominio óptico, para realizar la conectividad entre las diferentes unidades (por ejemplo CPU y memoria), con tal de superar estas limitaciones. Los dispositivos fabricados con la tecnología zero-change CMOS representan una solución muy atractiva para el diseño de links ópticos dentro de un chip. Esta técnica utiliza procesos CMOS actuales, beneficiándose así enormemente de la fácil integración con dispositivos electrónicos actuales. Diseñar y caracterizar dispositivos trabajando con zero-change CMOS es clave para el futuro de las interconexiones ópticas. Esta tesis presenta la caracterización tanto teórica como experimental de un modulador tipo ring resonator de Silicon-Germanium. Es el primer modulador de depletion utilizando SiGe como un material activo. Además, este dispositivo muestra el desplazamiento en longitud de onda más grande publicado hasta la fecha, comparándolo con otros moduladores zero-change CMOS, mejorando el desplazamiento de dispositivos de puro silicio. La demostración de este dispositivo comienza una nueva era de diseños de moduladores ópticos que utilizaran silicon-germanium para mejorar la eficiencia de modulación, y por lo tanto reducir el consumo de potencia.Les interconnexions elèctriques de super-computadors i microprocessadors de alt rendiment representen actualment un coll d'ampolla en quant a ample de banda i potència consumida. Es necessita una migració cap al domini òptic, per realitzar la connectivitat entre les diferents unitats (per exemple entre la CPU i la memòria), per tal de superar aquests problemes. Els dispositius fabricats sota zero-change CMOS technology representen una solució molt atractiva al disseny de links òptics dins d'un xip. Aquesta tècnica utilitza processos CMOS actuals, tenint enormes beneficis en quant a la integració amb dispositius electrònics actuals. Dissenyar i caracteritzar dispositius treballant amb zero-change CMOS és clau pel futur de les interconnexions òptiques del futur. Aquesta tesi presenta la caracterització tant teòrica com experimental d'un modulador ring resonator de Silicon-Germanium. Representa el primer modulador de depletion usant SiGe con un material actiu. A més a més, aquest dispositiu mostra el desplaçament en longitud d'ona més gran publicat fins ara en qualsevol dispositiu zero-change CMOS, millorant el desplaçament de dispositius de pur silici. La demostració d'aquest dispositiu comença una nova era de dissenys de moduladors òptics que utilitzaran silicon-germanium per millorar l'eficiència de modulació i per tant per reduir el consum de potència

Optical interconnect solution with plasmonic modulator and Ge photodetector array

We report on an optical chip-to-chip interconnect solution, thereby demonstrating plasmonics as a solution for ultra-dense, high-speed short-reach communications. The interconnect comprises a densely integrated plasmonic Mach-Zehnder modulator array that is packaged with standard driving electronics. On the receiver side, a germanium photodetector array is integrated with trans-impedance amplifiers. A multicore fiber provides a compact optical interface to the array. We demonstrate 4 × 20 Gb/s on-off keying signaling with direct detection.ISSN:1041-1135ISSN:1941-017

Monolithic quantum-dot distributed feedback laser array on silicon

Electrically-pumped lasers directly grown on silicon are key devices interfacing silicon microelectronics and photonics. We report here, for the first time, an electrically-pumped, room-temperature, continuous-wave (CW) and single-mode distributed feedback (DFB) laser array fabricated in InAs/GaAs quantum-dot (QD) gain material epitaxially grown on silicon. CW threshold currents as low as 12 mA and single-mode side mode suppression ratios (SMSRs) as high as 50 dB have been achieved from individual devices in the array. The laser array, compatible with state-of-the-art coarse wavelength division multiplexing (CWDM) systems, has a well-aligned channel spacing of 20 0.2 nm and exhibits a record wavelength coverage range of 100 nm, the full span of the O-band. These results indicate that, for the first time, the performance of lasers epitaxially grown on silicon is elevated to a point approaching real-world CWDM applications, demonstrating the great potential of this technology

Diffractive sidewall grating coupler: towards 2D free-space optics on chip.

Silicon photonics has been the subject of intense research efforts. In order to implement complex integrated silicon photonic devices and systems, a wide range of robust building blocks is needed. Waveguide couplers are fundamental devices in integrated optics, enabling different functionalities such as power dividers, spot-size converters, coherent hybrids and fiber-chip coupling interfaces, to name a few. In this work we propose a new type of nanophotonic coupler based on sidewall grating (SIGRA) concept. SIGRAs have been used in the Bragg regime, for filtering applications, as well as in the sub-wavelength regime in multimode interference (MMI) couplers. However, the use of SIGRAs in the radiation regime has been very limited. Specifically, a coarse wavelength division multiplexer was proposed and experimentally validated. In this work we study the use of SIGRAs in the diffractive regime as a mean to couple the light between a silicon wire waveguide mode and a continuum of slab waveguide modes. We also propose an original technique for designing SIGRA based couplers, enabling the synthesis of arbitrary radiation field profile by Floquet- Bloch analysis of individual diffracting elements while substantially alleviating computational load. Results are further validated by 3D FDTD simulations which confirm that the radiated field profile closely matches the target design field.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Integrated optical isolators using electrically driven acoustic waves

We propose and investigate the performance of integrated photonic isolators based on non-reciprocal mode conversion facilitated by unidirectional, traveling acoustic waves. A triply-guided waveguide system on-chip, comprising two optical modes and an electrically-driven acoustic mode, facilitates the non-reciprocal mode conversion and is combined with modal filters to create the isolator. The co-guided and co-traveling arrangement enables isolation with no additional optical loss, without magnetic-optic materials, and low power consumption. The approach is theoretically evaluated and simulations predict over 20 dB of isolation and 2.6 dB of insertion loss with 370 GHz optical bandwidth and a 1 cm device length. The isolator utilizes only 1 mW of electrical drive power, an improvement of 1-3 orders of magnitude over the state-of-the-art. The electronic driving and lack of magneto-optic materials suggest the potential for straightforward integration with the drive circuitry, possibly in monolithic CMOS technology, enabling a fully contained `black box' optical isolator with two optical ports and DC electrical power.Comment: 14 pages, 5 figures, 1 table. Relies on an acoustic-optical multiplexer introduced in arXiv:2007.11520, which has been separated out in this updated version of the paper for clarity. Additionally, this updated version included additional discussion of design considerations of the isolato