The Optical Parametric Oscillator (OPO), one of today’s most known optical devices, can be functionally defined as a widely tunable coherent source. Like the laser, it is based on the resonant feedback provided to an optical amplifier by a cavity. Unlike the laser, it relies on parametric amplification instead of stimulated emission and population inversion. This project aims at demonstrating the first electrically pumped OPO. Such result will constitute a major scientific breakthrough because at variance with the laser, whose heterostructure diode version has spurred the field of photonics, the quest for an electrically injected monolithic OPO is still open half a century after the original demonstration of the OPO. Today OPOs, pumped by conventional lasers, are available under very different time, spectral and power formats. Large segments of the related technology are at a mature stage for several industrial, military, health and environmental applications, with new commercial products being launched on the market at a growing rate. However, most of this market is still very connected to research mainly because of the limited portability of the current OPOs. Such limitation might be overcome by the diode-OPO (DOPO) to be developed in this project, which will emit in the near to mid infrared (1.5-3.5 µm) under CW operation at room temperature. The DOPO source that we will develop relies on intracavity parametric generation in a deeply etched narrow-stripe QD laser diode. Here the main advantage of using QDs is related to their ability to trap charge carriers and quench diffusion toward non-radiative recombination centers. For lasers, this effect enables the fabrication of deeply etched narrow-stripe (few µm) laser diodes with threshold currents comparable to those of broad area devices. This is the key for the demonstration of a DOPO, since the width of such narrow deeply etched ridge waveguides constitutes a very efficient degree of freedom to ensure phase matching in diode OPOs. In the key-enabling-technology field of photonics, the demonstration of a diode OPO would be a disruptive achievement for: 1) the telecom range, where the mode-hopping-free tunability of existing DFB and DBR lasers constitutes a strong limitation, and where there is presently a strong interest in largely tunable and wavelength-selectable sources, mainly for access networks; and 2) the eye-safe 2-3.5 µm window, which is widely used for civilian applications including gas sensing, security and medical applications, as well as for military applications. The availability of integrated components for this spectral range remains extremely limited, the devices operating in this range being largely restricted to stand-alone and narrow-band sources. The availability of diode-OPOs would induce a true revolution in both these fields due to their compactness, wide tunability, energetic efficiency and low cost, with a possible impact on sensors for environmental or medical monitoring. Concerning industrial property and technological transfer, the very same reasons behind the exceptional performance of the laser diode (compactness, low cost, low-power operation) would also boost the patent and industrial perspectives of the first DOPO. The delivered device and technology will allow the creation of IP, as already highlighted by a first patent jointly filed by INAC and MPQ while preparing this project. The competences of these partners in quantum-dot physics and nonlinear photonics are completed by a third research group, III-V Lab, a leader in the semiconductor photonic technology. Finally the presence, through III-V Lab, of the industrial partners Thales and Alcatel-Lucent, with their excellent track records in developing and bringing to the market novel advanced optoelectronic products, crucially strengthens the valorization perspectives for the DOPO project.

Located between the microwave and near-infrared regions of the electromagnetic spectrum, terahertz radiations have many attractive properties for imaging and for wireless data transmission applications. There are presently various devices, operating in the terahertz range, contemplated as basic building blocks of an imaging or a wireless transmission system. These devices are at different research stages, and breakthrough are still needed to reach the application stage. Terahertz imaging systems have become routine laboratory instruments and have found several niche and industrial applications. Nevertheless up to now, detectors still have relatively low-speed image acquisition. In parallel, over the past ten years, several groups have considered the prospects of using terahertz radiation as a means to transmit data for future multi-Gbit/s short-range communication systems. Presently, to fulfill the demand for higher data rates the only possibility is to increase the available bandwidth to several tens of gigahertz. This means the carrier frequency must be above 300 GHz. The creation of systems for wireless communication with sub-terahertz and terahertz carrier requires significant improvement of the detectors operating beyond 300 GHz, with high sensitivity and high-speed of operation. The main idea of the NADIA project is to explore the possibility of high-speed terahertz detectors using semiconductor-based devices. NADIA aims at bringing efficient detection by exploiting the new physical concept of ratchet effect. The spatial asymmetry created by the semi-circular antidot array of the ratchet cell forces electrons under the influence of the terahertz radiation to move preferentially towards the direction of the semi-disc axis. The resulting directed current is the detection signal. Until now a few novel ratchet-effect-based sub-THz detectors based on semiconductor nanostructures were proposed. Most of them have shown good responsivity and Noise Equivalent Power for frequencies below 300 GHz. In this project we will investigate in depth the underlying physical phenomena to widen the frequency range of detection and will tackle another very important characteristic of these devices – their speed. We propose exploration of improvements allowed by integrating these devices with high speed integrated circuits. Research in high-speed transistors is also driven by various applications, including very high speed/very high spectral efficiency optical transmissions, imaging and high-speed wireless communication, and more generally in the long-term aims at opening up the terahertz gap. Recent advances of InP HBTs with several hundred gigahertz operating frequencies qualify them as key components in such systems, e.g. for amplifier stages, local oscillators, modulation drivers, etc. In that respect, 0.7-µm InP DHBT technology developed in the consortium has demonstrated the best performances to achieve transistors reaching fT beyond 300 GHz and fmax beyond 400 GHz, while keeping the capability of actual medium-complexity circuit fabrication. The main challenge of NADIA for the HBT is to be able to efficiently rectify the alternating potential at the terahertz frequency induced by the incoming radiation into detectable DC photovoltage. One of the possible rectification mechanisms involves rectification by using the nonlinear behavior of the I-V characteristics. Taking advantage of its record bandwidth, InP HBT technology will enable new broadband terahertz detectors that offer also a high breakdown voltage, thanks to superior Johnson figure of merit. In addition, the ability to integrate antennas to efficiently couple the incident terahertz radiation will yield better detector performances. Finally we will compare the sensitivity, the Noise Equivalent Power, and speed of both ratchet cell and HBT based terahertz detectors.

As the communication bandwidth and the bandwidth density scale with Moore’s law, the reach-capability of copper links shrinks, while the optical solutions at very high data rates (enhanced by Wavelength Division Multiplexing -WDM-) are costly and power greedy. 850nm Vertical Cavity Surface Emitting Laser (VCSEL) links dominate at distances from 1 to a few 100 meters, where they provide a significant cost and power benefit, but this solution does not scale with the interconnect needs of mass market applications, such as high performance computer applications and data center applications. The PICSEL project focuses on the development of a new Silicon-Photonics hybrid III/V-on-Si-laser source. The PICSEL source is a long-wavelength (1.5µm to 1.3µm) Vertical Cavity Laser, where bottom and top mirrors are replaced by silicon Photonic Crystal grating-Mirrors (PCM), 1-making the cavity shorter, 2-enabling precise frequency laser emission according to accurately-controlled wavelengths through the lithographic definition of the filling factor of the crystal grating-mirror, and, 3-allowing edge-coupling of the light into a waveguide. With the proposed source, called VCSEEL for “Vertical Cavity Surface and Edge Emitting Laser”, the PICSEL project addresses fabrication cost, bandwidth density (high capacity, high integration density) and power efficiency issues: - Fabrication cost: the PICSEL laser source will be developed in cost-effective mass-scale CMOS front-end fabrication lines; - High capacity: the VCSEEL source is expected to be faster than conventional VCSELs thanks to shorter cavity lengths, thus it has the potentiality to be modulated at higher bitrates; it also offers scalability of the bandwidth density, thanks to its capability to “edge-emit” light into a silicon waveguide, thus enabling WDM-multiplexing of VCSEEL-array into a single waveguide; - High integration density: the aforementioned WDM capability of edge-emission of VCSEELs enables higher integration density, as several (n>4) channels using several VCSEEL lasers can be designed and fabricated on a same chipset, when using an integrated multiplexer (such as AWG), nx10Gbps or nx25Gbps chip-sets will considerably increase the integration density thus substantially decrease the equipment footprint. - Power efficiency: sub milli-amperes threshold current and 20% wall-plug efficiency typical for VCSEL source, are expected. This novel technology paves the way for a new generation of VCSEL devices which should result in a fully successful replacement of the present VCSEL photonics, by employing existing CMOS processing capability, allowing for a high-throughput mass fabrication. Also, the complete renewal of physical concepts will result in the broadening of accessible functionality and application spectra and grants solid perspectives of a promising industrial potential, whose far-reaching future developments can hardly be appreciated in full as today. This later upstream aspect will be addressed in PICSEL and a specific functionality will be demonstrated: the free-space beam steering of arrays of VCSEELs. With a complementary and vertically-integrated consortium covering the whole food-chain, including design, fabrication, and test and with CMOS-compatible front-end processes and III-V-fab available back-end processes, the project PICSEL paves the way for a 3-year-term industrial solution. In addition, “upstream” concepts, enabled by the proposed laser architecture, will be investigated as they are expected to offer enhanced transmission and processing performances.

The main goal of the LIGNEDEMIR project is to develop InAlGaAs quaternaries lattice-matched on InP with monolayer control of composition and interface abruptness using MOCVD. These quaternaries give an added degree of freedom in the design of intersubband devices based on the InAlAs/InGaAs/InP material system. More specifically, the quaternaries will replace InAlAs barriers, enabling on to design bound-to-continuum optical transistions centered at 5µm and enabling the LIGNEDEMIR consortium to propose two key missing components: rapid and sensitive QWIPs and modulators based on Schottky or Stark-shift designs. These two components along best-in-class QCLs fabricated on InP will lay the foundation for a full-fledged mid-infrared photonic integrated platform with applications in lab-on-chip chemical and biological spectroscopy. To achieve these ambitious objectives, the LIGNEDEMIR project will tightly interweave numerical simulations, material growth and characterization and device processing and characterization. Specifically, advanced characterizations using scanning electron transmission microscopy will be applied to all samples fabricated in the project, providing precise information on the concentration and strain at atomic level. This wealth of data will be used to refine numerical models used to simulate the band structure and charge transport in the QWIPs and modulators. All data from simulations will be cross-checked against measurements with exhaustive device characterizations. Though the project specifically focuses on MOCVD-grown InAlGaAs alloys lattice-matched on InP, all findings of the project will be useful for other material systems and growth techniques.

The N-GREEN project targets the current ICT challenges: the ever-growing global data traffic and unsustainable increase of energy consumption. The main bottleneck is the switching, extremely power-hungry in current electronic switch/routers. N-GREEN proposes a new type of switching/routing node by introducing a new high-capacity design including new optical technologies to reduce by several orders of magnitude the energy consumption per bit switched. The project targets modelling and proof of concept of this novel node, focusing on: • A backplane, highly integrated yet modular, based on fast optical switches of small connectivity but addressing large switching capacities, thanks to the WDM technique. This technique is compatible with the conventional packet switching technique, while addressing a switching capacity beyond 100 Tb/s (160 Tbit/s for a 16x16 optical switch). • A network architecture exploiting WDM packets thanks to a new generation of optical add/drop multiplexers (WSADM: WDM slotted add/drop multiplexer). These packets having a fixed duration close to 1 µs are transported in a transparent way, to better exploit the switching matrix of the node; their headers will be transported over one dedicated wavelength at a lower bit rate, to reduce the physical constraints of the electronic processing and scheduler. • New interfaces improving the interconnection of data storage and processing units. These interfaces support new functionalities such as dynamical bandwidth allocation and secured interconnection. These innovations allow limiting the amount of data to be electronically handled, while introducing a limited number of optical components thanks to WDM slots, thus reducing energy consumption per transmitted bit. This project is built around the following criteria: • A partnership having the right expertise: The partners of N-GREEN have the different skills required to achieve the project’s goals. Many of these international experts are active in the steering committees of technical conferences such as Photonics in Switching (PS) or Optical Network Design and Modelling (ONDM). The partners of N-GREEN have previously worked together in the ANR ECOFRAME project. • Pragmatic directions, to provide a concrete answer to the needs of the market: N-GREEN proposes to study a new switch/router exploiting a 2012 patent of Alcatel-Lucent. N-GREEN capitalizes on real innovations: the dynamic optical bypass and line card interconnection. N-GREEN targets a well-identified market and proposes a new technology to be deployed beyond 2020. Due to the challenges to address, it is critical to start the proof of concept as soon as possible if the industrial version is to reach the market in time. • A workplan structured in 4 technical work-packages and one management work-package focused on: • Design and develop the N-GREEN network architecture, relying on strategic data provided by industry, compliant with emerging software- defined networks (SDN) and network function virtualisation (NFV). • Design in detail and model the switching/routing node for a feasibility study. • Analyse network and node performance, including a benchmarking analysis for comparison with existing solutions. • Experimentally demonstrate a proof of concept of the node. • Valorise and disseminate this new approach through patents, scientific conferences and publications, and setting up workshops towards a new standardisation process. Thus, N-GREEN offers new perspectives for the future telecommunication network by proposing a new generation of eco-designed switch/routers, creating the required conditions to take leadership in the domain of optical networks.