Recently, the desired very high throughput of 5G wireless networks drives millimeter-wave (mm-wave) communication into practical applications. A phased array technique is required to increase the effective antenna aperture at mm-wave frequency. Integrated solutions of beamforming/beam steering are extremely attractive for practical implementations. After a discussion on the basic principles of radio beam steering, we review and explore the recent advanced integration techniques of silicon-based electronic integrated circuits (EICs), photonic integrated circuits (PICs), and antenna-on-chip (AoC). For EIC, the latest advanced designs of on-chip true time delay (TTD) are explored. Even with such advances, the fundamental loss of a silicon-based EIC still exists, which can be solved by advanced PIC solutions with ultra-broad bandwidth and low loss. Advanced PIC designs for mm-wave beam steering are then reviewed with emphasis on an optical TTD. Different from the mature silicon-based EIC, the photonic integration technology for PIC is still under development. In this paper, we review and explore the potential photonic integration platforms and discuss how a monolithic integration based on photonic membranes fits the photonic mm-wave beam steering application, especially for the ease of EIC and PIC integration on a single chip. To combine EIC, for its accurate and mature fabrication techniques, with PIC, for its ultra-broad bandwidth and low loss, a hierarchical mm-wave beam steering chip with large-array Manuscript delays realized in PIC and sub-array delays realized in EIC can be a future-proof solution. Moreover, the antenna units can be further integrated on such a chip using AoC techniques. Among the mentioned techniques, the integration trends on device and system levels are discussed extensively.Index Terms-5G, millimeter-wave, beam steering, true-timedelay, phase shifter, antenna-on-chip, photonic radio beam steering, broadband beamforming, phase control units. 0018-9197

In this paper, we propose a reconfigurable beam-shaping system to permit energy-efficient non-line-of-sight (NLOS) free-space optical communication. Light is steered around obstacles blocking the direct communication pathway and reaches a receiver after reflecting off of a diffuse surface. A coherent array optical transmitter (CAO-Tx) is used to spatially shape the wavefront of the light incident on a diffuse surface. Wavefront shaping is used to enhance the amount of diffusely reflected light reaching the optical receiver. Synthetic NLOS experiments for a signal reflected over an angular range of 20° are presented. A record-breaking 30-Gbit/s orthogonal frequency-division multiplexing signal is transmitted over a diffused optical wireless link with a >17-dB gain.

We demonstrate error-free 320 Gb/s SOA-based optical wavelength conversion. By utilizing optical filtering, an effective recovery time of less than 1.8 ps is achieved in an SOA, which ensures 320 Gb/s operation. OCIS codes: (190.5970) Semiconductor nonlinear optics, (250.5980) Semiconductor optical amplifier 1. Introduction All-optical wavelength converters (AOWCs) are considered as important building blocks in the future high-capacity wavelength-division-multiplexed networks. AOWCs that utilize nonlinearities of semiconductor optical amplifiers (SOAs) have attracted considerable research interest due to the integration ability and power efficiency [1]. A number of SOA-based AOWCs have been demonstrated [2][3][4][5]. However, the slow SOA recovery time (typically several tens to hundred ps) can cause unwanted pattern effects in the converted signal, which limits the maximum operation speed.In this paper, we present for the first time an error-free and pattern-independent 320 Gb/s wavelength conversion using a single SOA. To our best knowledge, this is the highest operation speed for SOA-based wavelength conversion. The wavelength converter is constructed by using commercially available fiber pigtailed components. The SOA in the experiment is a commercial product (Kamelian nonlinear SOA), having an initial fully gain recovery time of 56 ps. We demonstrate that the effective recovery time of the SOA can dramatically shorten to less than 1.8 ps by using optical filtering. A delayed-interferometer is utilized to change the inverted signal into noninverted signal. The wavelength converter has a simple configuration, operates at low optical power, and this concept allows photonic integration. The work was funded by STW EET6491 and IST-LASAGNE (FP6-507509).

DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Microwave photonics (MWP) studies the interaction between microwaves and optical waves for the generation, transmission, and processing of microwave signals (i.e., three key domains), taking advantage of the broad bandwidth and low loss offered by modern photonics. Integrated MWP using photonic integrated circuits (PICs) can reach a compact, reliable, and green implementation. Most PICs, however, are recently developed to perform one or more functions restricted inside a single domain. Herein, as highly desired, a multifunctional PIC is proposed to cover the three key domains. The PIC is fabricated on an InP platform by monolithically integrating four laser diodes and two modulators. Using the multifunctional PIC, seven fundamental functions across microwave signal generation, transmission, and processing are demonstrated experimentally. Outdoor field trials for electromagnetic environment surveillance along in-service high-speed railways are also performed. The success of such a PIC marks a key step forward for practical and massive MWP implementations.