Suchergebnisse

The demand for high-speed mobile wireless communications is growing at a very fast rate.WDM technology is a key technique for achieving the high data rate and spectral efficiency requirements for wireless communication systems. Wavelength division Multiplexing (WDM) [3–6] has emerged as a successful air-interfacetechnique. TheWavelength division Multiplexing was originally developed from the multi-carrier modulation techniques used in high wavelength military radios. This thesis presents, a simulink based simulation system is implemented using Additive White Gaussian Noise channel (AWGN) to study the performance analysis of Bit Error rate (BER) Vs Signal to Noise ratio (SNR). The model of WDM with Rician fading channel using simulink in MATLAB is discussed. This model is used for performance enhancement of the WDM with QPSK and QAM modulation schemes and channel condition. The throughput and packet error rate are used to evaluate the performance of MAC layer with the change in physical layer parameter.The performance analysis of different technique used in the QAM WDM is compared by visualizing the BER vs SNR curve.

This is the final version. Available on open access from De Gruyter via the DOI in this record ; The integration of artificial intelligence (AI) systems in the daily life greatly increases the amount of data generated and processed. In addition to the large computational power required, the hardware needs to be compact and energy efficient. One promising approach to fulfill those requirements is phase-change material based photonic neuromorphic computing that enables in-memory computation and a high degree of parallelization. In the following, we present an optimized layout of a photonic tensor core (PTC) which is designed to perform real valued matrix vector multiplications and operates at telecommunication wavelengths. We deploy the well-studied phase-change material Ge2Sb2Te5 (GST) as an optical attenuator to perform single positive valued multiplications. In order to generalize the multiplication to arbitrary real factors, we develop a novel symmetric multiplication unit which directly includes a reference-computation branch. The variable GST attenuator enables a modulation depth of 5 dB over a wavelength range of 100 nm with a wavelength dependency below 0.8 dB. The passive photonic circuit itself ensures equal coupling to the main-computation and reference-computation branch over the complete wavelength range. For the first time, we integrate wavelength multiplexers (MUX) together with a photonic crossbar array on-chip, paving the way towards fully integrated systems. The MUX are crucial for the PTC since they enable multiple computational channels in a single photonic crossbar array. We minimize the crosstalk between the channels by designing Bragg scattering based MUX. By cascading, we achieve an extinction ratio larger than 61 dB while the insertion loss is below 1 dB. ; Deutsche Forschungsgemeinschaft (DFG) ; European Research Council (ERC) ; European Union Horizon 2020 ; Studienstiftung des deutschen Volkes

In this paper, a random distributed feedback fiber laser is proposed as a multiplexing scheme for ultralong range measurements (up to 200 km). Optical fiber sensors are time and wavelength multiplexed overcoming one of the main limitations of long-range sensing setups, which is their limited multiplexing capability. The direct modulation of the laser's cavity allows the interrogation of sensors by measuring the reflected power for different wavelengths and distances. Fiber Bragg gratings placed at different fiber locations and wavelengths have been interrogated in two different sensor networks. In addition, in order to improve the performance of the system, some features have been analyzed. ; This work was supported by the Spanish Government project TEC2013-47264-C2-2-R and the FEDER funds.

11 pags., 9 figs. ; Current bandwidth capacity provided by wavelength-division multiplexing and polarization-division multiplexing is insufficient to keep up with the increasing bandwidth demand required for new services. Mode-division multiplexing technology paves the way to further increase transmission and bandwidth capacities in photonic interconnects. In this work, we propose an ultra-broadband two-mode converter and de/multiplexer based on a sub-wavelength engineered multimode interference coupler, a 90° phase shifter, and a symmetric Y-junction for the silicon-on-insulator platform. Sub-wavelength grating waveguides enable dispersion engineering to further increase the bandwidth operation of conventional multimode interference coupler and, subsequently, of mode de/multiplexer based on them. Full three-dimensional simulations of the designed mode converter and de/multiplexer show insertion loss below than 0.84 dB and crosstalk lower than -20 dB over an unprecedented bandwidth of 300 nm (1.4-1.7 μm). The overall footprint of the proposed device is only 36 μ m × 3.7 μm. ; This work was supported in part by the Spanish Ministry of Economy and Competitiveness under Grant TEC2015-71127-C2-1-R (FPI scholarship BES-2016-077798), Grant TEC2016-80718-R, and Grant IJCI-2016-30484, in part by the Community of Madrid under Grant S2013/MIT-2790, in part by the EMPIR program (JRP-i22 14IND13 Photind), co-financed by the participating countries and the European Union's Horizon 2020 research and innovation program, and in part by the Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant 734331 ; Peer Reviewed

365 374 62 2 ; S ; "(c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.") The advanced television system committee (ATSC) is to release the next-generation U.S. digital terrestrial television standard, known as ATSC 3.0. Layered division multiplexing (LDM) is one of the new physical layer technologies included in the standard, which enables the efficient provision of mobile and fixed services by superposing two independent signals with different power levels. ATSC 3.0 has also adopted a novel transmission technique known as channel bonding (CB), which splits the data of a service into two sub-streams that are modulated and transmitted over two radio-frequency (RF) channels. This paper investigates the potential use cases, implementation aspects, and performance advantages, for combining LDM with CB and also with the multi-RF channel technology time frequency slicing (TFS) introduced in digital video broadcasting - terrestrial second generation (DVB-T2) (as an informative annex) and digital video broadcasting - next generation handheld (DVB-NGH) which allows distributing the data of a service across two or more RF channels by means of time slicing and frequency hopping. Parts of this paper have been published in the Proceedings of the IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, Ghent, Belgium, in 2015. This work was supported by the ICT Research and Development Program of MSIP/IITP. [R0101-15-294, Development of Service and Transmission Technology for Convergent Realistic Broadcast.] Garro Crevillén, E.; Gimenez Gandia, JJ.; Park, SI.; Gómez Barquero, D. (2016). Layered Division Multiplexing With Multi-Radio-Frequency Channel Technologies. IEEE Transactions on Broadcasting. ...

Mención Internacional en el título de doctor ; El objetivo de este trabajo se centra especialmente en el desarrollo de sensores de fibra óptica y técnicas de autoreferencia para la medida de la temperatura en diferentes entornos industriales. El primer objetivo de este trabajo consiste en el diseño y desarrollo de un sensor de fibra óptica de bajo coste para la medida de la temperatura en transformadores de potencia y aplicaciones biomédicas. En estas aplicaciones, el uso de sensores de temperatura tradicionales resulta inadecuado debido a la presencia de fuertes interferencias electromagnéticas que pueden perturbar la lectura de la temperatura. Uno de los requisitos fundamentales para diseñar un sensor de temperatura que pueda usarse en aplicaciones biomédicas es el uso de materiales biocompatibles en su fabricación. En este sentido, una configuración simple que permite cumplir con los requisitos mencionados anteriormente es la modulación por intensidad en fibras poliméricas. Este tipo de sensores basan la lectura de la temperatura en medir las variaciones de potencia óptica en función de los cambios de temperatura que se aplican sobre el sensor. En este contexto, el uso de la tecnología asociada con la fibra óptica de plástico ofrece ventajas competitivas frente a otros materiales, como son: el uso de dispositivos opto-electrónicos de bajo coste, la posibilidad de utilizar conectores de baja precisión, la posibilidad de utilizar multiplexores y demultiplexores de muy bajo coste, entre muchas otras ventajas. A pesar de estas ventajas, los sensores de intensidad necesitan de esquemas de autoreferencia que eviten fluctuaciones de potencia que interfieran en la lectura de la temperatura. Estas fluctuaciones pueden provenir de fluctuaciones de potencia a lo largo del tramo de fibra óptica entre la unidad de control y el sensor, fluctuaciones de la fuente de luz por cambios en la corriente de alimentación, pérdidas de potencia por envejecimiento de la instalación, entre otras causas. El segundo objetivo de este trabajo consiste en promover el estudio y el desarrollo de técnicas de multiplexado y autoreferencia que implementen sensores fabricados en fibra óptica de plástico. Estas topologías deberán de utilizar dispositivos eficientes desde el punto de vista del consumo de potencia para mejorar con ello el balance de potencias del sistema y por tanto, poder utilizar este tipo de esquemas en redes de corto y medio alcance. Para alcanzar este objetivo, en este trabajo se desarrollan técnicas de autoreferencia y multiplexado de bajo coste basadas en multiplexación por longitud de onda vasta (CWDM, Coarse Wavelength Division Multiplexing). Esta técnica se caracteriza por su amplio desarrollo en el campo de telecomunicaciones como estándar para aplicaciones de corto o medio alcance en redes metropolitanas. Los multiplexores y demultiplexores diseñados para esta topología tienen una rejilla de longitudes de onda con una separación entre canales de 20nm. Este espaciado entre canales dificulta la multiplexación de un elevado número de dispositivos o sensores como podría llevarse a cabo si se usaran dispositivos basados en multiplexación por longitud de onda densa (DWDM, Dense Wavelength Division Multiplexing). Pero presentan una clara ventaja competitiva, los esquemas CWDM requieren bajas tolerancias en la fabricación de fuentes de luz, un control menos exhaustivo de la temperatura de la fuente, filtros ópticos de bajo coste y esquemas de diseño menos complejos. Los menores requisitos técnicos de los dispositivos utilizados con esta tecnología hacen que sea una topología interesante para su uso en redes de sensores de bajo coste. El tercer objetivo consiste en desarrollar sensores sin contacto basados en pirometría de dos colores para el sensado de la temperatura en procesos de mecanizado industrial. ; As a general aim, this work specifically focuses on the development of temperature sensors and self-reference techniques for temperature measurement in different industrial sectors. The first objective of this work is the design and development of a low-cost fiber optic sensor for measuring temperature in power transformers and biomedical applications where the presence of EMI prohibits the use of traditional sensors. Compatibility with the human being is a requirement when the temperature sensors are used in medical applications. Following simple fiber optic configurations, intensity sensors modulate the optical power loss as the temperature changes, thus providing the measurement as an optical intensity modulation signal. Polymer Optical Fiber (POF) technology, with very low-cost components, enables temperature sensing using a low precision connectors and lenses as well as simple multiplexing and demultiplexing devices, especially if compared with glass optical fibers. However, intensity sensors need a self-referencing method to minimize the influences of long-term aging of source and receptor characteristics, as well as undesirable random short-term fluctuations of optical power loss in the fiber link connecting the control unit, where the measurements are taken, to the remote sensing point, where the optical sensor is located. The second objective of this work is to promote, study and develop a multiplexing strategy to implement and scale POF sensor networks using low cost off-the-shelf devices, enhancing the power budget and keeping the self-reference of the measurements. This work focuses on low-cost Coarse WDM (CWDM) technology, where a grid of wavelengths with a 20nm channel spacing for target distance of up to tens of kilometres is specified. CWDM technology have lately been promoted in the field of telecommunication as standard for metro applications with shorter distances, lower network capacity and cost than Dense WDM (DWDM). This topology requires simpler, wider tolerance laser manufacturing, less laser accurate temperature control and reduced design complexity and cost of optical filters. These relaxed requirements make the CWDM technology an interesting approach for building low-cost self-referencing sensors networks. The development of this technology, adapted to the use of POF, can be carried out with the development of fiber Bragg gratings (FBG) in POF, providing an effective and compact strategy for exploiting fiber links for both propagating directions of the light with a single fiber lead. The third objective is to develop a non-contact two-colour fiber-optic pyrometer for temperature measures in the aerospace machining industry, enhancing the location measurement area, reducing the surface emissivity effect and keeping the self-reference of the measurement… ; The research work of this dissertation has been supported by the following Spanish projects: TEC2009-14718-C03-03 (DEDOS), and TEC2012-37983-C03-02 (CFOOT-TIC) of the Spanish Interministerial Commission of Science and Technology (CICYT); BES-2010-033348, EEBB-I-12-05434 and EEBB-1-13-07511 of the Spanish Ministry of Economy and Competitiveness; PRX12/00007 of Spanish Ministry of Education; P2013/MIT-2790, FACTOTEM-2/2010/00068/001 and S2013/MIT-2790 (SINFOTON-CM) of Autonomous Community of Madrid. Additional financial support was obtained from ICT COST Action TD1001: Novel and Reliable Optical Fiber Sensor Systems for Future Security and Safety Applications (OFSESA) of the European Union. ; Programa Oficial de Doctorado en Ingeniería Eléctrica, Electrónica y Automática ; Presidente: Tianxin Yang.- Secretario: Ricardo Vergaz Benito.- Vocal: Kevin Heggarty

[EN] A mechanical mode converter for mode division multiplexed systems over SSMF at 850 nm is proposed and evaluated experimentally by the transmission of OOK-modulated optical signals. The proposed mode converter is based on a periodic structure defined by the grating period (Λ) parameter and the number of mode coupling points, N. A mechanical grating with N=50 points and a tunable grating period (Λ form 440 to 456 μm) has been designed offering a 124-nm tuning bandwidth. The LP01 mode to LP11 mode conversion has been experimentally assessed and a conversion efficiency of 89 % has been achieved in the designed device. Optical transmission of OOK-modulated signals with 1.25 and 2.5 Gb/s bitrates on LP01 mode or a converted LP11 mode is demonstrated achieving BER 10−9 after 1-km optical transmission over SSMF at 850 nm ; This work was supported in part by the Spanish Ministerio de Economia y Competitividad MINECO/FEDER, European Union under Project TEC2015-70858-C2-1-R XCORE and in part by MINECO under Project RTC-2014-2232-3 HIDRASENSE. ; García Rodríguez, D.; Corral González, JL.; Llorente Sáez, R. (2017). Mode Conversion for Mode Division Multiplexing at 850 nm in Standard SMF. IEEE PHOTONICS TECHNOLOGY LETTERS. 29(11):929-932. https://doi.org/10.1109/LPT.2017.2694605 ; S ; 929 ; 932 ; 29 ; 11

An experimental comparison of stability between two different fiber laser topologies is carried out. The lasers are based on ring resonators that include highly-doped Er-fibers. Both topologies use fiber Bragg grating reflectors in order to select the emission wavelengths. The experimental results confirms that the novel topology based on fiber optic circulators arranged in an hybrid serial-parallel configuration offers a better stability and higher optical signal to noise ratios (OSNR) than the simpler based on a parallel configuration. ; This work was supported in part by the Spanish Government TEC2007-67987-C02, European COST-299.

The demand for high-speed mobile wireless communications is growing at a very fast rate. OFDM technology is a key technique for achieving the high data rate and spectral efficiency requirements for wireless communication systems. Frequency division Multiplexing (OFDM) [3–6] has emerged as a successful air-interface technique. The Frequency division Multiplexing was originally developed from the multi-carrier modulation techniques used in high Frequency military radios. This thesis presents, a simulink based simulation system is implemented using Additive White Gaussian Noise channel (AWGN) to study the performance analysis of Bit Error rate (BER) Vs Signal to Noise ratio (SNR). The model of OFDM with Rician fading channel using simulink in MATLAB is discussed. This model is used for performance enhancement of the OFDM with QPSK and QAM modulation schemes and channel condition. The throughput and packet error rate are used to evaluate the performance of MAC layer with the change in physical layer parameter. The performance analysis of different technique used in the QAM OFDM is compared by visualizing the BER vs SNR curve

We propose and demonstrate two ultra-long range fiber Bragg grating (FBG) sensor interrogation systems. In the first approach four FBGs are located 200 km from the monitoring station and a signal to noise ratio of 20 dB is obtained. The second improved version is able to detect the four multiplexed FBGs placed 250 km away, offering a signal to noise ratio of 6-8 dB. Consequently, this last system represents the longest range FBG sensor system reported so far that includes fiber sensor multiplexing capability. Both simple systems are based on a wavelength swept laser to scan the reflection spectra of the FBGs, and they are composed by two identical-lengths optical paths: the first one intended to launch the amplified laser signal by means of Raman amplification and the other one is employed to guide the reflection signal to the reception system. ; This work was supported by the Spanish Government project TEC2010-20224-C02-01.

[EN] This paper reports different proposals in the field of the Super-structured Fiber Bragg Gratings for Coherent Direct Sequence OCDMA applications providing enhanced fea- tures in terms of available spectral bandwidth, spectral efficiency and inter-channel rejection suitable for WDM and OCDMA combined applications. The reported de- vices cover the multiband en-decoders covering different bands on the same device, the almost rectangular envelope en-decoders demonstrated for both 1 and 5 ITU- 100GHz bands providing flat response and a roll-off better than 5 dB/GHz, and finally a multidimensional WDM/CODE/SPACE multiplexing proposal based on the concatenation of rectangular SSFBGs. ; This work was supported by the Spanish Government project TEC 2009-12169, and the Valencian Government under the project ACOMP/2010/023. ; Baños López, R.; Pastor Abellán, D.; García Muñoz, V.; Amaya Ocampo, WA. (2013). Super-structured Fiber Bragg Gratings with improved features for Coherent Direct Sequence OCDMA. Waves. 5(1):5-12. http://hdl.handle.net/10251/57917 ; S ; 5 ; 12 ; 5 ; 1

This paper investigates fundamental limitations of optical frequency transfer stability, related to cost-effective implementation of signal transmission in duplex, unidirectional optical paths offered by a standard Dense Wavelength Division Multiplexing (DWDM) network. We pointed out the effect of significant mismatch of phase fluctuations observed in pairs of fibers even when located in a common cable. We also measured the thermal sensitivities of individual DWDM optical modules in the context of the effectiveness of the signal stabilization system. Finally, we present the real implementation of the coherent optical carrier transfer in operational DWDM network, showing the overall impact of all individual effects. We demonstrated that using soil-deployed cables, it is possible to obtain the long-term stability (one day averaging) within the range from 2´10−16 to 4´10−16 and typical frequency offset at the level of few times 10−16 in a 1500 km long line. ; Funding: European Union (EU), Horizon 2020, EMPIR, 18SIB06, TiFOON, Advanced time/frequency comparison and dissemination through optical telecommunication networks

Space-division multiplexing (SDM) attracts attention to cladding-pumped optical amplifiers, but they suffer from a low pump power conversion efficiency. To address this issue, ytterbium (Yb3+) and erbium (Er3+) co-doping is considered as an effective approach. However, it changes the gain profile of Er3+-doped fiber amplifiers and induces the gain difference between optical wavelengths in the C-band, significantly limiting the effective band of the dense wavelength-division multiplexed (DWDM) system. This paper is devoted to a detailed study of a cladding-pumped Er3+/Yb3+ co-doped fiber amplifier (EYDFA) through numerical simulations aiming to identify a configuration, before assembling a similar EYDFA in our laboratory premises that ensures the desired performance. The simulation model is based on a commercial double cladding EYDF whose parameters are experimentally extracted and fed to the EYDFA setup for the system-level studies. We investigate the wavelength dependence of the amplifier's characteristics (absolute gain, gain uniformity, noise figure) and bit error rate (BER) performance for several DWDM channels and their optical power. The obtained results show that a 7 m long EYDF and co-propagating pump direction is preferable for the EYDFA with a 3 W pump source at 975 nm and with the given gain medium characteristics for WDM applications. For instance, it ensures a gain of 19.7–28.3 dB and a noise figure of 3.7–4.2 dB when amplifying 40 DWDM channels with the input power of −20 dBm per channel. Besides, we study EYDFA gain bandwidth and the maximum output power when operating close to the saturation regime and perform a sensitivity analysis showing how the doped fiber's absorption and emission cross-sections impact the amplification process through energy transfer from Yb3+ to Er3+. Finally, we quantify the power penalty introduced by the EYDFA; the results show that it is not higher than 0.1 dB when amplifying 40 × 10 Gbps non-return-to-zero on-off keying signals from −20 dBm/channel.---//---This work is licensed under a CC BY 4.0 license. ; This work has been supported by the European Regional Development Fund project No.1.1.1.1/18/A/068. The Institute of Solid State Physics, University of Latvia as a Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.