Breaking FOV-Aperture Trade-Off with Multi-Mode Nano-Photonic Antennas

Nano-photonic antennas are one of the key components in integrated photonic transmitter and receiver systems. Conventionally, grating couplers, designed to couple into an optical fiber, suffering from limitations such as large footprint and small field-of-view (FOV) have been used as on-chip antennas. The challenge of the antenna design is more pronounced for the receiver systems, where both the collected power by the antenna and its FOV often need to be maximized. While some novel solutions have been demonstrated recently, identifying fundamental limits and trade-offs in nano-photonic antenna design is essential for devising compact antenna structures with improved performance. In this paper, the fundamental electromagnetic limits, as well as fabrication imposed constraints on improving antenna effective aperture and FOV are studied, and approximated performance upper limits are derived and quantified. By deviating from the conventional assumptions leading to these limits, high-performance multi-mode antenna structures with performance characteristics beyond the conventional perceived limits are demonstrated. Finally, the application of a pillar multi-mode antenna in a dense array is discussed, an antenna array with more than 95% collection efficiency and 170∘ FOV is demonstrated, and a coherent receiving system utilizing such an aperture is presented

Breaking FOV-Aperture Trade-Off with Multi-Mode Nano-Photonic Antennas

Nano-photonic antennas are one of the key components in integrated photonic transmitter and receiver systems. Conventionally, grating couplers, designed to couple into an optical fiber, suffering from limitations such as large footprint and small field-of-view (FOV) have been used as on-chip antennas. The challenge of the antenna design is more pronounced for the receiver systems, where both the collected power by the antenna and its FOV often need to be maximized. While some novel solutions have been demonstrated recently, identifying fundamental limits and trade-offs in nano-photonic antenna design is essential for devising compact antenna structures with improved performance. In this paper, the fundamental electromagnetic limits, as well as fabrication imposed constraints on improving antenna effective aperture and FOV are studied, and approximated performance upper limits are derived and quantified. By deviating from the conventional assumptions leading to these limits, high-performance multi-mode antenna structures with performance characteristics beyond the conventional perceived limits are demonstrated. Finally, the application of a pillar multi-mode antenna in a dense array is discussed, an antenna array with more than 95% collection efficiency and 170∘ FOV is demonstrated, and a coherent receiving system utilizing such an aperture is presented

Antennas and Propagation Aspects for Emerging Wireless Communication Technologies

The increasing demand for high data rate applications and the delivery of zero-latency multimedia content drives technological evolutions towards the design and implementation of next-generation broadband wireless networks. In this context, various novel technologies have been introduced, such as millimeter wave (mmWave) transmission, massive multiple input multiple output (MIMO) systems, and non-orthogonal multiple access (NOMA) schemes in order to support the vision of fifth generation (5G) wireless cellular networks. The introduction of these technologies, however, is inextricably connected with a holistic redesign of the current transceiver structures, as well as the network architecture reconfiguration. To this end, ultra-dense network deployment along with distributed massive MIMO technologies and intermediate relay nodes have been proposed, among others, in order to ensure an improved quality of services to all mobile users. In the same framework, the design and evaluation of novel antenna configurations able to support wideband applications is of utmost importance for 5G context support. Furthermore, in order to design reliable 5G systems, the channel characterization in these frequencies and in the complex propagation environments cannot be ignored because it plays a significant role. In this Special Issue, fourteen papers are published, covering various aspects of novel antenna designs for broadband applications, propagation models at mmWave bands, the deployment of NOMA techniques, radio network planning for 5G networks, and multi-beam antenna technologies for 5G wireless communications

Integrated Photonic Platforms for Quantum Technology: A Review

Quantum information processing has conceptually changed the way we process and transmit information. Quantum physics, which explains the strange behaviour of matter at the microscopic dimensions, has matured into a quantum technology that can harness this strange behaviour for technological applications with far-reaching consequences, which uses quantum bits (qubits) for information processing. Experiments suggest that photons are the most successful candidates for realising qubits, which indicates that integrated photonic platforms will play a crucial role in realising quantum technology. This paper surveys the various photonic platforms based on different materials for quantum information processing. The future of this technology depends on the successful materials that can be used to universally realise quantum devices, similar to silicon, which shaped the industry towards the end of the last century. Though a prediction is implausible at this point, we provide an overview of the current status of research on the platforms based on various materials.Comment: 48 pages, 3 figure

Efficient nanoscale photonic devices and monolithic electronic-photonic subsystems in sub-100 nm SOI CMOS

We demonstrate efficient photonic devices that rely on sub-100nm features in unmodified 45nm SOI CMOS, including photonic crystals, array-antenna grating couplers, and modulators. We then show monolithically integrated electronicphotonic systems comprising millions of transistors and thousands of photonic devices, including a complete chip-to-chip photonic link

Antenas fotônicas compactas compatíveis com a tecnologia CMOS

Orientador: Lucas Heitzmann GabrielliTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: A área das antenas fotônicas desenvolveu-se muito nos últimos anos, com aplicações diretas em detecção de luz e avaliação de distância (LIDAR), microscopia, fotovoltaica, holografia, e as comunicações inter-chip e intra-chip ¿ entre outras. Da ampla variedade de antenas relatadas na literatura, as antenas fotônicas compatíveis com a tecnologia de semicondutores de óxido metálico complementar (CMOS) são candidatas promissoras para resolver o gargalo das comunicações em nível de chip, e também prometem levar a tecnologia LIDAR para aplicações comerciais viáveis de última geração como os carros autônomos. Dentre as antenas propostas na literatura a antena do tipo grade é a mais utilizada devido a sua facilidade de projeção e fabricação, e a seu desempenho. Embora a antena de tipo grade seja adequada para várias aplicações, esta ainda tem várias desvantagens. Entre estas, sua forte dependência da polarização e do comprimento de onda, sua direção de radiação máxima inclinada, e seu desempenho ineficiente quando projetada com uma área efetiva próxima a um comprimento de onda operacional. Nesta tese, apresentamos o projeto de antenas com desenhos não-intuitivos utilizando algoritmos de otimização do estado da arte, para aplicações em acoplamento da fibra para o chip, e também para seu uso em arranjos. Por um lado, produzimos conhecimento local na área de fabricação e caracterização de antenas de silício sobre isolante (SOI), desenvolvendo receitas de fabricação com alta repetibilidade em cada etapa do processo. Por outro lado, mostramos que as antenas otimizadas podem superar algumas limitações das antenas tipo grade. As simulações mostram que nosso projeto de antena para acoplamento atinge uma eficiência de acoplamento vertical de?6.3 dB e uma largura de banda operacional de 3 dB de 60 nm. Sendo esta a menor antena para acoplamento com esse nível de desempenho na literatura, ela ocupa apenas 15 % do espaço de uma antena convencional tipo grade para acoplamento, o que possibilita seu uso para acoplamento em fibras com múltiplos núcleos. Também mostramos experimentalmente pela primeira vez uma antena com radiação totalmente vertical para utilização em arranjos com um tamanho compacto, perto do comprimento de onda, com uma área de 1.78 µm × 1.78 µm, e uma largura de banda operacional maior do que 100 nm. Finalmente, mostramos um arranjo de antenas passivo integrado de 8 elementos distribuídos seguindo o desenho aperiódico da espiral de Fermat apresentando um nível de lóbulo lateral (SLL) cerca de 1 dB menor que o equivalente periódico do mesmo tamanho num comprimento de onda de 1550 nm. Além disso, também se usou um modulador espacial de luz (SLM) a um comprimento de onda visível para emular arranjos de antenas maiores, mostrando que a distribuição dos elementos seguindo a espiral Fermat é capaz de reduzir o SLL para arranjos de até 64 elementos espaçados até 581'lambda'Abstract: The field of photonic antennas has become an area of intensive study in recent years, with direct applications in light detection and ranging (LIDAR), microscopy, sensors, photovoltaics, holography, and inter- and intra-chip communications ¿ among several others. Of the great variety of antennas reported in the literature, the photonic antennas compatible with the well-established complementary metal¿oxide¿semiconductor (CMOS) technology are promising candidates to solve the chip-level communication bottleneck, and also promise to make the LIDAR technology a viable commercial application for autonomous vehicles. Among the antennas proposed in the literature we find that the grating-type antenna is the most widely used due to its straightforward design and manufacture, and its performance. However, even if grating antennas are suitable for several applications, they still present several drawbacks. In particular, their radiation properties are strongly dependent on polarization and wavelength, their direction of maximum radiation does not occur at broadside direction, and they are power inefficient when designed with an effective area close to the operating wavelength. In this thesis, we present the design of antennas with counterintuitive designs obtained by means of state-of-the-art optimization algorithms for applications in fiber coupling to the chip, and also for use as radiation element in large-scale arrays. We produced, on the one hand, local knowledge in the manufacturing and characterization of silicon-on-insulator (SOI) antennas, developing manufacturing recipes with high repeatabil-ity at each step of the process. On the other hand, we show that optimized antennas can overcome some limitations of grating-type antennas. Simulations show that our antenna designed for coupling achieves an efficiency in the vertical direction of ?6.3 dB and an operating 3 dB bandwidth of 60 nm. This represents the smallest antenna designed for coupling at this performance level in the literature, it occupies only 15 % of the footprint of a conventional grating antenna, which in turn enables its use in multicore fibers. We also demonstrated experimentally for the first time an antenna with vertical radiation anda compact footprint for use in arrays. Its dimensions are close to the operation wavelength, and it has an area 1.78 µm × 1.78 µm and an operational bandwidth exceeding 100 nm. Finally, we show that a passive integrated 8-element array antenna distributed following the aperiodic design of the Fermat spiral shows a side lobe level (SLL) approximately 1 dB lower than a periodic array of the same size, both operating at a wavelength of 1550 nm. In addition, we also use a spatial ligth modulator (SLM) at visible wavelength to emulate larger arrays, showing that the Fermat spiral successfully reduces the SLL in for arrays with up to 64-elements spaced by 581'lambda'DoutoradoTelecomunicações e TelemáticaDoutor em Engenharia ElétricaCAPE

Automatic Tuning of Silicon Photonics Millimeter-Wave Transceivers Building Blocks

Today, continuously growing wireless traffic have guided the progress in the wireless communication systems. Now, evolution towards next generation (5G) wireless communication systems are actively researched to accommodate expanding future data traffic. As one of the most promising candidates, integrating photonic devices in to the existing wireless system is considered to improve the performance of the systems. Emerging silicon photonic integrated circuits lead this integration more practically, and open new possibilities to the future communication systems. In this dissertation, the development of the electrical wireless communication systems are briefly explained. Also, development of the microwave photonics and silicon photonics are described to understand the possibility of the hybrid SiP integrated wireless communication systems. A limitation of the current electrical wireless systems are addressed, and hybrid integrated mm-wave silicon photonic receiver, and silicon photonic beamforming transmitter are proposed and analyzed in system level. In the proposed mm-wave silicon photonic receiver has 4th order pole-zero silicon photonic filter in the system. Photonic devices are vulnerable to the process and temperature variations. It requires manual calibration, which is expensive, time consuming, and prone to human errors. Therefore, precise automatic calibration solution with modified silicon photonic filter structure is proposed and demonstrated. This dissertation demonstrates fully automatic tuning of silicon photonic all-pass filter (APF)-based pole/zero filters using a monitor-based tuning method that calibrates the initial response by controlling each pole and zero individually via micro-heaters. The proposed tuning approach calibrates severely degraded initial responses to the designed elliptic filter shapes and allows for automatic bandwidth and center frequency reconfiguration of these filters. This algorithm is demonstrated on 2nd- and 4th-order filters fabricated in a standard silicon photonics foundry process. After the initial calibration, only 300ms is required to reconfigure a filter to a different center frequency. Thermal crosstalk between the micro-heaters is investigated, with substrate thinning demonstrated to suppress this effect and reduce filter calibration to less than half of the original thick substrate times. This fully automatic tuning approach opens the possibility of employing silicon photonic filters in real communication systems. Also, in the proposed beamforming transmitter, true-time delay ring resonator based 1x4 beamforming network is imbedded. A proposed monitor-based tuning method compensates fabrication variations and thermal crosstalk by controlling micro-heaters individually using electrical monitors. The proposed tuning approach successfully demonstrated calibration of OBFN from severely degraded initial responses to well-defined group delay response required for the targeted radiating angle with a range of 60◦ (-30◦ to 30◦ ) in a linear beamforming antenna array. This algorithm is demonstrated on OBFN fabricated in a standard silicon photonics foundry process. The calibrated OBFN operates at 30GHz and provide 2GHz bandwidth. This fully automatic tuning approach opens the possibility of employing silicon OBFN in real wideband mm-wave wireless communication systems by providing robust operating solutions. All the proposed photonic circuits are implemented using the standard silicon photonic technologies, and resulted in several publications in IEEE/OSA Journals and Conferences

Gradient metasurfaces: a review of fundamentals and applications

In the wake of intense research on metamaterials the two-dimensional analogue, known as metasurfaces, has attracted progressively increasing attention in recent years due to the ease of fabrication and smaller insertion losses, while enabling an unprecedented control over spatial distributions of transmitted and reflected optical fields. Metasurfaces represent optically thin planar arrays of resonant subwavelength elements that can be arranged in a strictly or quasi periodic fashion, or even in an aperiodic manner, depending on targeted optical wavefronts to be molded with their help. This paper reviews a broad subclass of metasurfaces, viz. gradient metasurfaces, which are devised to exhibit spatially varying optical responses resulting in spatially varying amplitudes, phases and polarizations of scattered fields. Starting with introducing the concept of gradient metasurfaces, we present classification of different metasurfaces from the viewpoint of their responses, differentiating electrical-dipole, geometric, reflective and Huygens' metasurfaces. The fundamental building blocks essential for the realization of metasurfaces are then discussed in order to elucidate the underlying physics of various physical realizations of both plasmonic and purely dielectric metasurfaces. We then overview the main applications of gradient metasurfaces, including waveplates, flat lenses, spiral phase plates, broadband absorbers, color printing, holograms, polarimeters and surface wave couplers. The review is terminated with a short section on recently developed nonlinear metasurfaces, followed by the outlook presenting our view on possible future developments and perspectives for future applications.Comment: Accepted for publication in Reports on Progress in Physic

Microstrip Patch Electrically Steerable Parasitic Array Radiators

This dissertation explores the expansion of the Electrically Steerable Parasitic Array Radiator (ESPAR) technology to arrays using microstrip patch elements. Scanning arrays of two and three closely-coupled rectangular patch elements are presented, which incorporate no phase shifters. These arrays achieve directive radiation patterns and scanning of up to 26° with maintained impedance match. The scanning is effected by tunable reactive loads which are used to control the mutual coupling between the elements, as well as additional loads which compensate to maintain the appropriate resonant frequency. The design incorporates theoretical analysis of the system of coupled antennas with full-wave simulation. A prototype of the threeelement array at 1 GHz is fabricated and measured to exhibit a maximum gain of 7.4 dBi with an efficiency of 79.1%. Further, the microstrip ESPAR is thoroughly compared to uniformlyilluminated arrays of similar size. To satisfy the need for higher directivity antennas with inexpensive electronic scanning, the microstrip ESPAR is then integrated as a subarray. The three-element subcell fabrication is simplified to a single layer with an inverted-Y groove in the ground plane, allowing for DC biasing without the need for the radial biasing stubs or tuning stubs found in the two-layer design. The 1 GHz ESPAR array employs a corporate feed network consisting of a Wilkinson power divider with switchable delay line phase shifts, ring hybrid couplers, and achieves a gain of 12.1 dBi at boresight with ±20° scanning and low side lobes. This array successfully illustrates the cost savings associated with ESPAR subarray scanning and the associated reduction in required number of phase shifters in the RF front end