Single mode polymer optical waveguides and out-of-plane coupling structure on a glass substrate

International audienceIn this paper, we propose an approach to improve silicon photonics-based optical transceivers packaging capabilities thanks to an optical and electrical interposer. We demonstrate the fabrication of polymer optical waveguides, single mode at telecom wavelengths using photosensitive resists and ultra-violet (UV) laser lithography on a glass substrate. Alongside the waveguides, a total internal reflection (TIR) based mirror is integrated for vertical redirection of the optical signal toward the silicon photonic integrated circuit (PIC). Femtosecond laser ablation is used for the mirror fabrication. Both the waveguides and the mirror have been optically characterized at 1310 nm. Total propagation losses of the waveguides have been measured at 5.5 dB for a 24.7 mm long waveguide. The mirrors present a circular distribution of the EM field

Functional packaging of RF, mmW and photonic functions based on femtosecond laser micromachining

International audienceThe increasing difficulty to pursue the aggressive objectives of Moore's law (More-Moore) has in parallel favored the emergence of integration solutions grouped under the term More-than-Moore, allowing to enrich silicon technologies by heterogeneous co-integration with new functionalities such as mixed digital/analog/RF/mmW circuits, antennas, sensors, actuators, embedded memory and other various microsystems). Still, it is clear that the performance of electronic systems (SoB - Systemon-Board) is far from having followed the same progression, thus marking a gap with monolithic nanometric CMOS technologies. To bridge this gap, it is now a question of producing gains in functionality, performance and compactness at the system level by heterogeneous integration of components in elemental system building blocks. Sometimes referred to as ‘System Moore’, this approach thus conceives the package not only as a simple encapsulation function but more precisely integrates the package as a functional system block. The dimensional level of functional packaging typically covers the 1-1000 µm range for which the use of microelectronics fabrication techniques are oversized, expensive and unable to efficiently handle thicknesses of a few tens of microns. In this context, laser micromachining is an increasingly used tool for micro/nanostructuring of materials for the packaging of integrated functions in photonics, microelectronics, RF and mmW. In this paper, we will first provide an overview of laser machining techniques in microelectronics and we will detailthe main characteristics of this technique with respect to the laser source and beam conditioning. It will be shown that the use of ultrashort laser processing with pulse width in femtosecond range is advantageous because it can be applied to a virtually unlimited range of materials like metals,semiconductors, dielectrics, alloys, and ceramics. The range of surface processing is diverse varying from a small scale (a few nm2) to large scale (a few mm2). The unwanted heat affected zone is greatly reduced for ultrashort lasers which allows for enhanced machining quality with low thermal impact of laser radiation on material. In a second step, we detail a selection of laser micromachining applications allowing either to increase the performance of RF and mmW components, or to introduce an innovative and distinctive manufacturing method promoting compactness and cost reduction:i) The first illustrated application is the fabrication of ultra-thin free standing membranes of SOICMOS RF circuits/functions on Silicon-on-Insulator (SOI) wafers. It will be shown that tremendous performance improvements can be obtained on a range of RF components like integrated inductances and power switches as well as in terms of cross-talk reduction.ii) The second example describes the packaging of an electro-optical transceiver using a glass electrooptical interposer to connect a silicon photonic chip to a single mode optical fiber.iii) Finally, the third illustration covers the fabrication of structures integrating mmW waveguides in G and J band [140-220 GHz, 220-320 GHz] with silicon chips and transitions allowing the conversion from coplanar to a guided mode in rectangular waveguides (WR5.1 and WR3.1)

Field Studies

One way to implement and evaluate the effectiveness of recommendation systems in software engineering is to conduct field studies. Field studies are important as they are the extension of laboratory experiments into real-life situations of organizations and/or society. They bring greater realism to the phenomena that are under study. However, field studies require following a rigorous research approach with many challenges attached, such as difficulties in implementing the research design, achieving sufficient control, replication, validity, and reliability. In practice, another challenge is to find organizations who are prepared to be studied. In this chapter, we provide a step-by-step process for the construction and deployment of recommendation systems in software engineering in the field. We also emphasize three main challenges (organizational, data, design) encountered during field studies, both in general and specifically with respect to software organizations

Revisiting Information Hiding: Reflections on Classical and Nonclassical Modularity

Abstract. What is modularity? Which kind of modularity should developers strive for? Despite decades of research on modularity, these basic questions have no definite answer. We submit that the common understanding of modularity, and in particular its notion of information hiding, is deeply rooted in classical logic. We analyze how classical modularity, based on classical logic, fails to address the needs of developers of large software systems, and encourage researchers to explore alternative visions of modularity, based on nonclassical logics, and henceforth called nonclassical modularity.