High link performance of Brillouin-loss based microwave bandpass photonic filters

We present a high link-performance multi-band microwave photonic filter based on stimulated Brillouin scattering (SBS) loss responses. The bandpass filter response is formed by suppressing the out-of-band signal using multiple broadened SBS loss responses, which avoids introducing additional noise in the passband. The low-noise SBS bandpass filter is implemented in an optimized high-performance MWP link, which enabled the demonstration of filter functionalities with a low noise figure, reconfigurability, and high resolution. A noise figure of 18.9 dB is achieved in the passband with a filter bandwidth of 0.3 GHz at a central frequency of 14 GHz, with a link gain of −13.9 dB and a spurious free dynamic range of 106 dB.Hz2/3. Bandwidth reconfiguration from 0.1 GHz to 1 GHz and multi-bandpass responses are also demonstrated

Photonic Microwave Filter With Steep Skirt Selectivity Based on Stimulated Brillouin Scattering

A method to enhance the filter slope of Brillouin-based photonic microwave filters is presented. This improvement is achieved by the combination of Brillouin gain and loss responses over phase-modulated signals. The experimental results show passband responses exhibiting a slope of 16.7 dB per octave, which corresponds with a threefold improvement in comparison to the natural Lorentzian response for the same gain.This work was supported in part by the Spanish Ministry of Economy and Competitiveness through TEC2016-80906-R project and by the European Union through TWEETHER project.Samaniego-Riera, D.; Vidal Rodriguez, B. (2016). Photonic Microwave Filter With Steep Skirt Selectivity Based on Stimulated Brillouin Scattering. IEEE Photonics Journal. 8(6). https://doi.org/10.1109/JPHOT.2016.2634782S8

OPTICAL PROCESSING BASED ON BRILLOUIN SCATTERING

[ES] Los efectos no lineales son herramientas valiosas en el procesamiento óptico. El obje-tivo de esta Tesis es contribuir con las nuevas arquitecturas y métodos a este campo, en particular al control de la polarización de la luz con luz y filtrado óptico de señales de microondas. La manipulación de las propiedades de la polarización de la luz en medios guiados es crucial en muchos sistemas ópticos clásicos y cuánticos. Sin embargo, la capacidad de la tecnología actual para definir con precisión el estado de polarización de determina-das longitudes de onda está lejos del nivel de madurez conseguido en el control de la amplitud. En el capítulo 3, se presenta un nuevo enfoque para el control totalmente óptico del estado de polarización con selectividad en longitud de onda, basado en el cambio del retardo fase por medio del stimulated Brillouin scattering. Los experimen-tos muestran que se puede llegar a cualquier punto de la esfera de Poincaré desde un estado de polarización de entrada arbitrario con tan solo una ligera variación en la amplitud de la señal (<2.5 dB). A diferencia de otros esquemas de procesamiento Bri-llouin, la degradación de la figura de ruido es pequeña (1.5 dB para una rotación completa en la esfera, 2pi). Este controlador de polarización completamente óptico puede forjar el desarrollo de nuevas técnicas basadas en la polarización en comunica-ciones ópticas, ingeniería laser, detección, sistemas cuánticos y sondeo basado en luz de sistemas químicos y biológicos. La segunda área de interés de la tesis se centra en el filtrado fotónico de microondas. La fotónica proporciona una implementación alternativa a los filtros de microondas. Las características proporcionadas por el scattering de Brillouin son muy atractivas para el diseño de filtro con especificaciones competitivas. El capítulo 4 está dedicado a los nuevos esquemas para el filtrado fotónico de microondas basado en SBS. En parti-cular, se presenta un método para mejorar la pendiente de los filtros fotónicos de mi-croondas basados en Brilouin. Esta mejora se logra mediante la combinación de las respuestas en ganancia y atenuación del Brillouin sobre la señal modulada en fase. Los resultados experimentales muestran una respuesta paso banda que exhibe una pendiente de 16.7 dB por octava, lo que corresponde con una mejora de 3 veces en comparación con la respuesta Lorentziana natural de la ganancia Brillouin. Sin embargo, la necesi-dad de 3 ondas de bombeo, es decir tres osciladores de microondas, incrementan la complejidad del sistema y dificulta la capacidad de ajuste. Para superar estas limita-ciones, se propone una segunda técnica para mejorar la pendiente de un filtro fotónico de microondas basado en scattering de Brillouin estimulado, el cual mantiene una fácil sintonización. Esta propuesta se basa en la dependencia de la polarización de la ganan-cia del Brillouin en fibras birrefringentes. La presencia de dos respuestas ortogonales de ganancia/atenuación Brillouin en fibras birrefringentes da como resultado dos res-puestas del filtro, que pueden ser sustraídas en un fotodetector balanceado para elimi-nar el lento decaimiento de la respuesta de ganancia natural Lorentziana del Brillouin. Los resultados experimentales muestran que se puede obtener una pendiente del filtro de 8.3 dB/oct. Finalmente, el documento de tesis proporciona conclusiones y actividades futuras abiertas por este trabajo de doctorado.[CA] Els efectes no lineals son ferramentes valuoses en el processament òptic. L'objectiu d'aquesta tesi es contribuir amb les noves arquitectures i mètodes a aquest camp, en particular al control de la polarització de la llum amb llum i filtrar òptic de senyals de microones. La manipulació de les propietats de la polarització de la llum en mitjans guiats es cru-cial en molts sistemes òptics clàssics i quàntics. No obstant això, la capacitat de la tecnologia actual per definir amb precisió l'estat de polarització de determinades lon-gituds d'ona està lluny del nivell de maduresa aconseguit en el control de l'amplitud. En el capítol 3, es presenta un nou enfocament per al control totalment òptic de l'estat de polarització amb selectivitat en longitud d'ona, basat en el canvi del retard de fase mitjançant el stimulated Brillouin scattering. Els experiments mostren que es pot arri-bar a qualsevol punt de l'esfera de Poincaré des d'un estat de polarització d'entrada arbitrari amb tant sols una lleugera variació de l'amplitud de la senyal (<2.5 dB). A diferencia d'altres esquemes de processament Brillouin, la degradació de la figura de soroll es petita (1.5 dB per a una rotació completa en l'esfera, 2pi). Aquest controlador de polarització completament òptic pot forjar el desenvolupament de noves tècniques basades en la polarització en comunicacions òptiques, enginyeria làser, detecció, sis-temes quàntics y sondeig basat en llum de sistemes químics i biològics. La segona àrea d'interès de la tesi es centra en el filtrar fotònic de microones. La fo-tònica proporciona una implementació alternativa als filtres de microones. Les caracte-rístiques proporcionades per el scattering de Brillouin son molt atractives per al dis-seny de filtres amb especificacions competitives. El capítol 4 està dedicat als nous esquemes per al filtrat fotònic de microones basat en SBS. En particular, es presenta un mètode per a millorar la pendent dels filtres fotònics de microones basats en Bri-llouin. Aquesta millora s'aconsegueix mitjançant la combinació de les respostes en guany i atenuació del Brillouin sobre la senyal modulada en fase. Els resultats experi-mentals mostren una resposta pas banda que exhibeix una pendent de 16.7 dB per octava, el que correspon amb una millora de 3 vegades en comparació amb la resposta Lorentziana natural del guany Brillouin. Tot i això, la necessitat de 3 ones de bom-beig, es a dir tres oscil·ladors de microones, incrementen la complexitat del sistema i dificulta la capacitat d'ajust. Per superar aquestes limitacions, es proposa una segona tècnica per millorar la pendent d'un filtre fotònic de microones basat en scattering de Brillouin estimulat, el qual manté una fàcil sintonització. Aquesta proposta es basa en la dependència de la polarització del guany del Brillouin en fibres birefringents. La presència de dos respostes ortogonals de guany/atenuació Brillouin en fibres birefrin-gents dona com a resultat dos respostes del filtre, que poden ser sostretes en un fotode-tector balancejat per eliminar el lent decaïment de la resposta de guany natural Lo-rentziana del Brillouin. Els resultats experimentals mostren que es pot obtenir una pendent del filtre de 8.3 dB/oct. Finalment, el document de tesi proporciona conclusions i activitat futures obertes per aquest treball de doctorat.[EN] Nonlinear effects are valuable tools in the field of optical processing. This Thesis is aimed at contributing with new architectures and methods to this field, in particular to the light-by-light control of polarization and optical filtering of microwave signals. The manipulation of the polarization properties of light in guided media is crucial in many classical and quantum optical systems. However, the capability of current technology to finely define the state of polarization of particular wavelengths is far from the level of maturity in amplitude control. In Chapter 3, a new approach for all-optical control of the state of polarization with wavelength selectivity based on the change of the phase retardance by means of stimulated Brillouin scattering is present-ed. Experiments show that any point on the Poincaré sphere can be reached from an arbitrary input state of polarization with little variation of the signal amplitude (< 2.5 dB). Unlike other Brillouin processing schemes, the degradation of the noise figure is small (1.5 dB for a full 2pi rotation). This all-optical polarization controller can forge the development of new polarization-based techniques in optical communication, laser engineering, sensing, quantum systems and light-based probing of chemical and biological systems. The second area of interest of the Thesis is photonic microwave filtering. Photonics provides an alternative implementation of microwave filters. The features provided by Brillouin scattering are very attractive to design filters with competitive specifications. Chapter 4 is devoted to new schemes for photonic microwave filtering based on SBS. In particular, a method to enhance the filter slope of Brillouin-based photonic microwave filters is presented. This improvement is achieved by the combination of Brillouin gain and loss responses over phase modulated signals. The experimental results show passband responses exhibiting a slope of 16.7 dB per octave, which corresponds with a 3-fold improvement in comparison to the natural Lorentzian response for the same gain. However, the need of three pump waves, i.e. three microwave oscillators, increases the system complexity and make tunability more difficult. To overcome these limitations, a second technique to enhance the slope of a photonic microwave filter based on stimulated Brillouin scattering is proposed, that maintains easy tunability. It relies on exploiting the polarization dependence of Brillouin gain in birefringent fibers. The presence of two orthogonal Brillouin gains/loss in birefringent fibers results in two filter responses that can be subtracted in a balanced photodetector to remove the slow Lorentzian decay of the natural Brillouin gain response. Experimental results show that a filter slope of 8.3 dB/oct can be obtained. Finally, the Thesis document provides conclusions and future activities opened by this PhD work.Samaniego Riera, DP. (2019). OPTICAL PROCESSING BASED ON BRILLOUIN SCATTERING [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/124820TESI

High-Performance On-Chip Microwave Photonic Signal Processing Using Linear and Nonlinear Optics

Manipulating and processing radio-frequency (RF) signals using integrated photonic devices has recently emerged as a paradigm-shifting technology for future microwave applications. This emerging technique is referred to as integrated microwave photonics (IMWP) which enables the high-frequency processing and unprecedentedly wideband tunability in compact photonic circuits, with significantly enhanced stability and robustness. However, to find widespread applications, the performance of IMWP devices must meet or exceed the achievable performance of conventional electronic counterparts. The work presented in this thesis investigates high-performance IMWP signal processing from two aspects: the optimized IMWP processing schemes and the photonic integration. Firstly, we explore novel schemes to improve the performance of chip-based microwave photonic subsystems, such as RF delay lines and RF filters which are basic building blocks of RF systems. A phase amplification technique is demonstrated to achieve a Si3N4 chip-based RF time delay with a delay tuning speed at gigahertz level. A new scheme to achieve an all-optimized RF photonic notch filter is demonstrated, producing a record-high RF link performance and complete functionalities. To unlock the potential of RF signal processing, we investigate a new filter concept of pairing linear and nonlinear optics for a high-performance RF photonic filter. To reduce the footprint of the novel IMWP filter, the photonic integration of both the ring resonators and Brillouin-active circuits on the same photonic chip is achieved. To eliminate the use of integrated optical circulators for on-chip SBS, on-chip backward inter-modal stimulated Brillouin scattering is predicted and experimentally demonstrated in a Si-Chalcogenide hybrid integrated photonic platform. The study and demonstrations presented in this thesis make the first viable step towards high-performance IMWP signal processing for real-world RF applications

Stimulated Brillouin Scattering in Integrated Circuits: Platforms and Applications

Coherent interactions between light and sound have been of significant interest since the invention of the laser. Stimulated Brillouin scattering (SBS) is a type of coherent interaction where light is scattered from optically generated acoustic waves. SBS is a powerful tool for optical and microwave signal processing, with applications ranging from telecommunications and Radar, to spatial sensing and microscopy. Over the last decade there has been increasing interest in the investigation of Brillouin scattering at device scales smaller than the wavelength of light. New interactions with the waveguide boundaries in these systems are capable of altering the strength of SBS, from complete suppression to orders of magnitude increases. The landmark demonstration of Brillouin scattering in planar waveguides, just six years ago, represents a new frontier for this field. This work explores the effective generation and harnessing of stimulated Brillouin scattering within modern photonic circuits. After establishing the foundations of linear and nonlinear optical circuits, we investigate the Brillouin processes available in multimode waveguides. We experimentally demonstrate giant Brillouin amplification using spiral waveguides consisting of soft-glass materials. We then integrate this soft-glass onto the standard platform for photonic circuits, silicon on insulator, without any reduction in performance. We apply these advanced devices to the field of microwave photonics and create high suppression microwave filters with functionality far beyond traditional electronic circuits. This thesis is a significant step towards Brillouin enabled integrated photonic processors

Controlling, storing and manipulating light using on-chip Brillouin scattering

The importance of optical signal processing techniques is growing rapidly in recent years due to the exponentially increasing demand for bandwidth, capacity and power efficiency in communications and computing. However, due to their bosonic nature photons do not interact with each other, unless there is a nonlinear medium mediating the interaction. One of the strongest nonlinear effects is the interaction of light waves, photons, with sound-waves, acoustic phonons, which is known as stimulated Brillouin scattering (SBS). This thesis experimentally investigates SBS in photonic chips. It is shown in this thesis that the fundamental interaction strength between light and sound waves can be tailored by using one-dimensional photonic bandgap structures, completely suppressing the effect or alternatively enhancing the interaction to form phase-locked Brillouin frequency combs. It was shown furthermore that efficiently generating SBS on-chip enables the generation of stable RF signals that are widely tunable in frequency. Finally, it is shown in this thesis that SBS enables the storage of light signals on a chip, one of the holy grails of all-optical signal processing. Delaying optical signals is of key importance in optical networks to enable synchronization, buffering, and rerouting. SBS enables large delays by resonantly transferring an optical signal to an acoustic wave, that travels five orders of magnitude slower and retrieving it after a certain storage time. It is demonstrated in this thesis that a Brillouin-based memory (BBM) technique allows storing amplitude and phase of optical data pulses and operate at multiple wavelengths with minimal cross-talk. Replenishing of the acoustic wave to overcome storage time limitations imposed by the lifetime of the acoustic wave as well as non-reciprocal light storage is also shown

Benefits of Spectral Property Engineering in Distributed Brillouin Fiber Sensing

As one of the most consolidated distributed fiber sensors based on stimulated Brillouin scattering, the Brillouin optical time-domain analyzer (BOTDA) has been developed for decades. Despite the commercial availability and outstanding progresses which has been achieved, the intrinsic Lorentzian gain spectrum restricts the sensing performance from possible further enhancements and hence limits the field of validity of the technique. In this paper, the novel method of engineering the gain spectral properties of the Brillouin scattering and its application on static and dynamic BOTDA sensors will be reviewed. Such a spectral property engineering has not only provided improvements to BOTDA, but also might open a new way to enhance the performance of all kinds of distributed Brillouin fiber sensors

Microwave Photonic Signal Processing Using On-Chip Nonlinear Optics

The field of microwave photonics (MWP) emerged as a solution to the challenges faced by electronic systems when dealing with high-bandwidth RF and microwave signals. Photonic devices are capable of handling immense bandwidths thanks to the properties of light. MWP therefore employs such devices to process and distribute the information carried by RF and microwave signals, enabling significantly higher capacity compared to conventional electronics. The photonic devices traditionally used in MWP circuits have mainly comprised bulky components, such as spools of fibre and benchtop optical amplifiers. While achieving impressive performance, these systems were not capable of competing with electronics in terms of size and portability. More recently, research has focused on the application of photonic chip technology to the field of MWP in order to reap the benefits of integration, such as reductions in size, weight, cost, and power consumption. Integrated MWP however is still in its infancy, and ongoing research efforts are exploring new ways to match integrated photonic devices to the unique requirements of MWP circuits. This work investigates the application of on-chip nonlinear optical interactions to MWP. Nonlinear optics enables light-on-light interactions (not normally possible in a linear regime) which open a vast array of powerful functionalities. In particular, this thesis focuses on stimulated Brillouin scattering, resulting from the interaction of light with hypersonic sound waves, and four-wave mixing, where photons exchange energies. These two nonlinear effects are applied to implement MWP ultra-high suppression notch filters, wideband phase shifters, and ultra-fast instantaneous frequency measurement systems. Experimental demonstrations using integrated optical waveguides confirm record results