The application span of silicon photonics is rapidly evolving from high speed transceivers for data- and telecommunication to a broad range of functionalities for many different markets, especially in the sensing and computing space. As a result, the demand for new building blocks and enhanced performance is accelerating and diversifying. Heterogeneous integration of new materials, chips and thin-film chiplets is becoming of key importance in this context. But the implementation of industrial supply chains for this diverse need will be challenging and may require a new supply chain model with dedicated standardization and test methods at the interface between the actors involved. This opinion article discusses opportunities and challenges associated with heterogeneous integration in silicon photonics, in particular with respect to future market growth and the design of process flows for heterogeneous integration.

Optical links are moving to higher and higher transmission speeds while shrinking to shorter and shorter ranges where optical links are envisaged even at the chip scale. The scaling in data speed and span of the optical links demands modulators to be concurrently performant and cost-effective. Silicon photonics（Si Ph）, a photonic integrated circuit technology that leverages the fabrication sophistication of complementary metal-oxide-semiconductor technology, is well-positioned to deliver the performance, price, and manufacturing volume for the high-speed modulators of future optical communication links. Si Ph has relied on the plasma dispersion effect, either in injection, depletion, or accumulation mode, to demonstrate efficient high-speed modulators. The high-speed plasma dispersion silicon modulators have been commercially deployed and have demonstrated excellent performance. Recent years have seen a paradigm shift where the integration of various electro-refractive and electro-absorptive materials has opened up additional routes toward performant Si Ph modulators. These modulators are in the early years of their development.They promise to extend the performance beyond the limits set by the physical properties of silicon.The focus of our study is to provide a comprehensive review of contemporary（i.e., plasma dispersion modulators） and new modulator implementations that involve the integration of novel materials with Si Ph.

Programmable Photonic integrated circuits are optical chips where the flow of light is configured through electronics. This provides a flexible way to explore new photonic functions, and a lower threshold for deployment in new applications.

The consolidation of the silicon photonics ecosystem has gained a lot of momentum in recent years. This is attributed to various initiatives in Europe and elsewhere as well. Despite these efforts, there are still outstanding issues that need to be resolved to further empower fabless end-users through a supply chain that is predictable, low risk, on-time, and provides low-cost services. This paper discusses topics such as design IP, diversity in platforms, access for prototyping (in particular MPW), skilled personnel, and routes for manufacturing in silicon photonics. These issues are of key importance for the development of a high-performance silicon photonics ecosystem. Furthermore, the paper describes how ePIXfab – the European Silicon Photonics Alliance – is playing its role to develop a silicon photonics ecosystem in Europe that can meet end-users expectations consistently.

Programmable photonic circuits are optical chips whose functionality can be (re)configured through electronics and software. This programmability enables new functionality, and opens the path to general-purpose photonic chips, similar to electronic FPGAs. This tutorial discusses the operational principles and technology stack for these chips.

We look at the opportunities presented by the new concepts of generic programmable photonic integrated circuits (PIC) to deploy photonics on a larger scale.Programmable PICs consist of waveguide meshes of tunable couplers and phase shifters that can be reconfigured in software to define diverse functions and arbitrary connectivity between the input and output ports.Off-the-shelf programmable PICs can dramatically shorten the development time and deployment costs of new photonic products, as they bypass the design-fabrication cycle of a custom PIC.These chips, which actually consist of an entire technology stack of photonics, electronics packaging and software, can potentially be manufactured cheaper and in larger volumes than application-specific PICs.We look into the technology requirements of these generic programmable PICs and discuss the economy of scale.Finally, we make a qualitative analysis of the possible application spaces where generic programmable PICs can play an enabling role, especially to companies who do not have an in-depth background in PIC technology.

Offering open-access silicon photonics-based technologies has played a pivotal role in unleashing this technology from research laboratories to industry. Fabless enterprises rely on the open-access of these technologies for their product development. In the last decade, a diverse set of open-access technologies with medium and high technology readiness levels have emerged. This paper provides a review of the open-access silicon and silicon nitride photonic IC technologies offered by the pilot lines of European research institutes and companies. The Abdul Rahim, Jeroen Goyvaerts and Roel Baets are with the Photonics Research Group, Department of Information Technology, Ghent University imec and Center for Nanoand Biophotonics, Ghent University, Ghent B9000, Belgium (e-mail: abdul.rahim@ugent.be, jeroen.goyvaerts@ugent.be, roel.baets@ugent.be). Bertrand Szelag and Jean-Marc Fedeli are with the Commissariat à l’Energie Atomique et aux Energie Alternatives, University Grenoble Alpes and CEA, LETI, MINATEC Campus, F-38054 Grenoble Cedex, France (email: bertrand.szelag@cea.fr, jean-marc.fedeli@cea.fr). Philippe Absil is with Imec, Kapeldreef 75, 3001 Leuven (e-mail: absilp@imec.be). Timo Aalto and Mikko Harjanne are with VTT, Tietotie 3, Espoo, Finland (e-mail: timo.aalto@vtt.fi, mikko.harjanne@vtt.fi). Callum Littlejohns and Graham Reed are with Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK (e-mail: c.littlejohns@soton.ac.uk, g.reed@soton.ac.uk). Georg Winzer, Stefan Lischke and Dieter Knoll are with IHP Leibniz-Institut für innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany (e-mail: winzer@ihp-microelectronics.com, lischke@ihp-microelectronics.com). Lars Zimmermann is with IHP Leibniz-Institut für innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany and Siliziumphotonik, Institut für Hochfrequenzund Halbleiter Systemtechnologien, Fakultät IV, Einsteinufer 25, 10587 Berlin, Germany (e-mail: lzimmermann@ihp-microelectronics.com). Douwe Geuzebroek and Arne Leinse are with LioniX International BV, Hengelosestrat 500, Enschede the Netherlands (email: d.h.geuzebroek@lionixint.com, a.leinse@lionix-int.com). Michael Geiselmann and Michael Zervas are with LIGENTEC, EPFL Innovation Park C,1015 Lausanne, Switzerland (e-mail: michael.geiselmann@ligentec.com, michael.zervas@ligentec.com). Hilde Jans and Andim Stassen are with Imec, Kapeldreef 75, 3001 Leuven (e-mail: hilde.jans@imec.be, andim.stassen@imec.be) Carlos Domı́nguez is with Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC). Campus UAB. 08193-Bellaterra, Spain (e-mail: carlos.dominguez@imb-cnm.csic.es). Pascual Muñoz is with Photonics Research Labs, Universitat Politécnica de Valencia, c/ Camino de Vera s/n, 46021 Valencia, Spain (e-mail: pascual.munoz@upv.es). David Domenech is with VLC Photonics S.L., c/ Camino de Vera s/n, 46021 Valencia, Spain (e-mail: jose.domenech@vlcphotonics.com). Anna Lena Giesecke is with AMO GmbH, Otto-Blumenthal-Str. 25, 52074 Aachen, Germany (e-mail: giesecke@amo.de). Max C. Lemme is with RWTH Aachen University, Otto-Blumenthal-Str. 2, 52074 Aachen and AMO GmbH, Otto-Blumenthal-Str. 25, 52074 Aachen, Germany (e-mail: lemme@amo.de). Roel Baets and Abdul Rahim coordinate ePIXfab, the European Silicon Photonics alliance. Manuscript received December 21, 2018; revised Month xx, 20xx. paper also highlights upcoming features of these platforms and discusses how they address the long-term market needs.

Offering open-access silicon photonics-based technologies has played a pivotal role in unleashing this technology from research laboratories to industry. Fabless enterprises rely on the open-access of these technologies for their product development. In the last decade, a diverse set of open-access technologies with medium and high technology readiness levels have emerged. This paper provides a review of the open-access silicon and silicon nitride photonic IC technologies offered by the pilot lines of European research institutes and companies. The paper also highlights upcoming features of these platforms and discusses how they address the long-term market needs.

We demonstrate nanosecond fast wavelength switching with a heterogeneously integrated III-V-on-silicon four-channel filtered feedback tunable laser. High-speed direct modulation at 12.5 Gbit/s of each wavelength channel is achieved.

Analog radio-over-fiber transceivers allow a substantial reduction in the complexity of the remote radio heads in the wireless network of the future. In this letter, we discuss the building blocks for such a transceiver implemented on a silicon photonics platform, with the heterogeneous integration of III-V devices and the co-integration with electronics. Transmission experiments that demonstrate the viability of such integrated analog transceivers are described.

Silicon Photonics is widely acknowledged as a gamechanging technology, driven by the needs of datacom and telecom. Silicon Photonics builds on highly capital-intensive manufacturing infrastructure, and mature open-access silicon photonics platforms are translating the technology from research fabs to industrial manufacturing levels. To meet the current market demands for silicon photonics manufacturing, a variety of openaccess platforms is offered by CMOS pilot lines, R&D institutes and commercial foundries. This paper presents an overview of existing and upcoming commercial and non-commercial openaccess silicon photonics technology platforms. We also discuss the diversity in these open-access platforms and their key differentiators.

A heterogeneously integrated InP-on-silicon fast tunable filtered feedback laser is demonstrated. The laser device consists of a main Fabry-Pérot cavity connected to an integrated arrayed waveguide grating of which the outputs form external cavities in which semiconductor optical amplifiers can be switched to provide single-mode operation and tunability. The laser can operate at four different wavelengths whereby switching between each wavelength channel is done within one nanosecond. For each wavelength channel 12.5 Gbit/s NRZ-OOK direct modulation is demonstrated. The combination of fast wavelength switching with straightforward wavelength control and high-speed direct modulation characteristics make the demonstrated laser structure very attractive for use in optical packet or burst switching systems.

A heterogeneously integrated InP-on-silicon fast tunable filtered feedback laser is demonstrated. The laser device consists of a main Fabry-Pérot cavity connected to an integrated arrayed waveguide grating of which the outputs form external cavities in which semiconductor optical amplifiers can be switched to provide single-mode operation and tunability. The laser can operate at four different wavelengths whereby switching between each wavelength channel is done within one nanosecond. For each wavelength channel 12.5 Gbit/s NRZ-OOK direct modulation is demonstrated. The combination of fast wavelength switching with straightforward wavelength control and high-speed direct modulation characteristics make the demonstrated laser structure very attractive for use in optical packet or burst switching systems.

Combined DMT and LTE data is transmitted over 5km SSMF using a directly modulated InP-on-Si laser and a silicon photonics receiver. We demonstrate DMT net capacity of 50 Gb/s while keeping the LTE EVM below 1%.

Silicon photonics is widely acknowledged as a game-changing technology, driven by the needs of datacom and telecom. Silicon photonics builds on highly capital-intensive manufacturing infrastructure, and mature open-access silicon photonics platforms are translating the technology from research fabs to industrial manufacturing levels. To meet the current market demands for silicon photonics manufacturing, a variety of open-access platforms is offered by CMOS pilot lines, R&D institutes, and commercial foundries. This paper presents an overview of existing and upcoming commercial and noncommercial open-access silicon photonics technology platforms. We also discuss the diversity in these open-access platforms and their key differentiators.

A multi-arm Mach-Zehnder interferometer based filter architecture is employed to demonstrate a 16-channel demultiplexer for optical Orthogonal Frequency ¡Division Multiplexed sign als. The fabricated filter shows average cross-talk of <;25 dB (best cross-talk of <; 35 dB) for all channels.

The high index contrast silicon-on-insulator platform is the dominant CMOS compatible platform for photonic integration. The successful use of silicon photonic chips in optical communication applications has now paved the way for new areas where photonic chips can be applied. It is already emerging as a competing technology for sensing and spectroscopic applications. This increasing range of applications for silicon photonics instigates an interest in exploring new materials, as silicon-on-insulator has some drawbacks for these emerging applications, e.g., silicon is not transparent in the visible wavelength range. Silicon nitride is an alternate material platform. It has moderately high index contrast, and like silicon-on-insulator, it uses CMOS processes to manufacture photonic integrated circuits. In this paper, the advantages and challenges associated with these two material platforms are discussed. The case of dispersive spectrometers, which are widely used in various silicon photonic applications, is presented for these two material platforms.

The chapter covers fundamentals of Silicon Photonic ICs including the driving forces, basic physics, technological implementations, current state of the art, ongoing R&D and trends for future research. The treatment includes all relevant devices excluding Silicon Photonics based sources. The chapter comprises specific sections on wavelength selective devices such as delay-line based- and ring resonator-based spectral filters, and covers grating couplers, waveguide-integrated germanium photodetectors, and optical isolators as well. Nonlinear optic devices constitute a more advanced topic, and its coverage includes fundamental aspects and a number of corresponding devices including wavelength converters, all optical amplifiers, phase sensitive amplifiers, and a section on the design of complex Silicon Photonic ICs.

A heterogeneously integrated InP-on-Si DFB laser, with direct modulation bandwidth of 21GHz has been used for the generation of a 69Gb/s discrete multi-tone signal. Transmission at 56Gb/s over 5 km SSMF is demonstrated as well.