Annealing-free Si3N4 frequency combs for monolithic integration with Si photonics

International audienceSilicon-nitride-on-insulator (SiNOI) is an attractive platform for optical frequency comb generation in the telecommunication band because of the low two-photon absorption and free carrier induced nonlinear loss when compared with crystalline silicon. However, the high-temperature annealing that has been used so far for demonstrating Si3N4-based frequency combs made the co-integration with silicon-based optoelectronics elusive, thus reducing dramatically its effective complementary metal oxide semiconductor (CMOS) compatibility. We report here on the fabrication and testing of annealing-free SiNOI nonlinear photonic circuits. In particular, we have developed a process to fabricate low-loss, annealing-free, and crack-free Si3N4 740-nm-thick films for Kerr-based nonlinear photonics featuring a full process compatibility with front-end silicon photonics. Experimental evidence shows that micro-resonators using such annealing-free silicon nitride films are capable of generating a frequency comb spanning 1300-2100 nm via optical parametrical oscillation based on four-wave mixing. This work constitutes a decisive step toward time-stable power-efficient Kerr-based broadband sources featuring full process compatibility with Si photonic integrated circuits (Si-PICs) on CMOS-.lines

A versatile silicon-silicon nitride photonics platform for enhanced functionalities and applications

Silicon photonics is one of the most prominent technology platforms for integrated photonics and can support a wide variety of applications. As we move towards a mature industrial core technology, we present the integration of silicon nitride (SiN) material to extend the capabilities of our silicon photonics platform. Depending on the application being targeted, we have developed several integration strategies for the incorporation of SiN. We present these processes, as well as key components for dedicated applications. In particular, we present the use of SiN for athermal multiplexing in optical transceivers for datacom applications, the nonlinear generation of frequency combs in SiN micro-resonators for ultra-high data rate transmission, spectroscopy or metrology applications and the use of SiN to realize optical phased arrays in the 800–1000 nm wavelength range for Light Detection And Ranging (LIDAR) applications. These functionalities are demonstrated using a 200 mm complementary metal-oxide-semiconductor (CMOS)-compatible pilot line, showing the versatility and scalability of the Si-SiN platform

a Method for Increasing Thermal Stability of Short-Living Solitons in Silicon Nitride Microresonators

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Confinement of activating receptors at the plasma membrane controls natural killer cell tolerance.

International audienceNatural killer (NK) cell tolerance to self is partly ensured by major histocompatibility complex (MHC) class I-specific inhibitory receptors on NK cells, which dampen their reactivity when engaged. However, NK cells that do not detect self MHC class I are not autoreactive. We used dynamic fluorescence correlation spectroscopy to show that MHC class I-independent NK cell tolerance in mice was associated with the presence of hyporesponsive NK cells in which both activating and inhibitory receptors were confined in an actin meshwork at the plasma membrane. In contrast, the recognition of self MHC class I by inhibitory receptors "educated" NK cells to become fully reactive, and activating NK cell receptors became dynamically compartmentalized in membrane nanodomains. We propose that the confinement of activating receptors at the plasma membrane is pivotal to ensuring the self-tolerance of NK cells

Compact soliton generation based on the butt-coupling between a Si3N4 microresonator and a DFB laser

International audienceWe exhibit the generation of soliton microcombs with 1.48-THz line spacing over 8.8 THz around 1575 nm by using the self-injection locking of a III-V DFB laser butt-coupled to a Si3N4 microresonator

Hyper-doped silicon nanoantennas and metasurfaces for tunable infrared plasmonics

6 pages, 4 figuresInternational audienceWe present the experimental realization of ordered arrays of hyper-doped silicon nanodisks, which exhibit a localized surface plasmon resonance. The plasmon is widely tunable in a spectral window between 2 and 5 $\mu$m by adjusting the free carrier concentration between 10$^{20}$ and 10$^{21}$ cm$^{-3}$. We show that strong infrared light absorption can be achieved with all-silicon plasmonic metasurfaces employing nano-structures with dimensions as low as 100\,nm in diameter and 23 nm in height. Our numerical simulations show an excellent agreement with the experimental data and provide physical insights on the impact of the nanostructure shape as well as of near-field effects on the optical properties of the metasurface. Our results open highly promising perspectives for integrated all-silicon-based plasmonic devices for instance for chemical or biological sensing or for thermal imaging

Compact optical frequency comb source based on a DFB butt-coupled to a silicon nitride microring

International audienceWe demonstrate an integrated Kerr frequency comb source based on the butt coupling between a III-V DFB laser and a silicon nitride (Si 3 N 4 ) microresonator. The 30-dB bandwidth of the optical comb is measured to be 148.7 nm (18 THz), centered at 1576 nm, which is, to the best of our knowledge, the largest ever measured on an ultra-compact source. This hybrid compact source can also be used for soliton investigations

Advanced solutions in silicon photonics using traditional fabrication methods and materials of CMOS technologies (Conference Presentation)

International audienceOptical signal modulation is presently done using Si pn junctions which cause phase shifting due to Soref effect and, put in a Mach-Zehnder configuration, produce interference and generate amplitude modulation. The drawback of pn junctions is the relatively low phase shifting efficiency which consequently inflicts high power consumptions on the electrical driver. An alternative device to pn junctions was developed and consists of introducing capacitive structures within the optical waveguide. The proposed device has the same crosssection footprint but is much shorter due to improved efficiencies. Typical pn-junctions can generate phase shifts of 60°/mm for the same implantation conditions. The device is made up of crystal Si, a thin SiO2 capacitor dielectric and poly-Si. Benchmarking the two phase shifters with respect to insertion losses, we observe that the proposed device is promising. Another material exhaustively used in CMOS technologies is Si3N4. In the data-communication bandwidths, the index contrast between Si3N4 (n = 1.95) and SiO2 (n=1.45) is smaller than that with Si (n = 3.5). Thus, nitride waveguides have lower optical mode confinements and are thus less sensitive to insertion losses caused by line edge roughness and wavelength shifting incurred by process variations. Moreover, the temperature induced index variations are 5 times les in Si3N4 than Si. Therefore, the use of nitride to fabricate devices in silicon photonics looks advantageous. However, high speed electro-optic devices are challenging in Si3N4. Consequently, a co-integration of both materials is essential. We developed a fabrication method and associated devices which allow to transfer the signal to and fro Si and Si3N4. We present some devices in each layer to illustrate the benefits

Record RF Performance (ft=180GHz and fmax=240GHz) of a FDSOI NMOS processed within a Low Thermal Budget for 3D Sequential Integration

International audienceRecord RF Figure-Of-Merits (FoM) is highlighted for a 42nm NMOS transistor fully processed at Low Thermal Budget (LTB) (&lt;500&deg;C) needed for 3D Sequential Integration (3DSI). f T =180GHz &amp; f MAX =240GHz are reported at V DD =0.9V; which is actually very similar to performance of reference Si MOSfets processed with a Hot Thermal Budget (HTB) (Fig. 15). This excellent result was possible thanks to a careful optimization of the LTB process after an advanced characterization and modeling of key technological parameters such as mobility, Gate-Capacitance and Gate resistance</p