Pluggable single-mode fiber-array-to-pic coupling using micro-lenses

Single-mode optical coupling between fiber and photonic integrated circuit (PIC) requires precision alignment and bonding, and significantly adds to the cost of photonic packaging. This article describes how a pair of micro-lens arrays-one on the Si-PIC and the other on the fiber-array-can be used to achieve fiber-to-PIC grating-coupling with an insertion-loss of 1.7 dB (i.e., a coupling efficiency of 68%) at 1300 nm, and a 1 dB alignment tolerance of +/- 30 mu m. Such relaxed tolerances allow for a "pluggable" connector to have a make-break insertion-loss reproducibility of 0.2 dB (one standard deviation)

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

Non-linear electron dynamics in semiconductor superlattices and dilute nitride alloys

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See-through holographic retinal projection display concept

International audienceThe field of near-eye see-through devices has recently received significant media attention and financial investments. However, devices demonstrated to date suffer from significant practical limitations resulting from the conventional optics on which they are based. Potential manufacturers seek to surpass these limitations using novel optical schemes. In this paper, we propose such a potentially disruptive optical technology that may be used for this application. Conceptually, our optical scheme is situated at the interface of geometric incoherent refractive imaging and radiative coherent diffractive imaging. The generation of an image occurs as a result of data transmission through a two-dimensional network of optical waveguides that addresses a distribution of switchable holographic elements. The device acts as a wavefront generator, and the eye is the only optical system in which the image is formed. In the following we describe the device concept and characteristics, as well as the results of initial simulations

SIN integrated optical phased arrays for two-dimensional beam steering at a single near-infrared wavelength

International audienceIn this work, we present two-dimensional beam steering in the near-infrared using a SiN integrated circuit, containing optical phased arrays. Beam steering was achieved over a range of 17.6 degrees x 3 degrees, at a fixed wavelength of 905 nm. The first dimension was steered via phase differences between the optical phased array channels. The second dimension was accessed by actively switching between various optical phased array sub-devices containing output diffraction gratings with different periods. The characterisation was performed on a wafer-level test station

Optimization of Silicon MZM Fabrication Parameters for High Speed Short Reach Interconnects at 1310 nm

Optical modulators are key components to realize photonic circuits, and Mach-Zehnder modulators (MZM) are often used for high speed short reach interconnects. In order to maximize the tolerable path loss of a transmission link at a given bitrate, the MZM needs to be optimized. However, the optimization can be complex since the overall link performance depends on various parameters, and, for the MZM in particular, implies several trade-offs between efficiency, losses, and bandwidth. In this work, we propose a general and rigorous method to optimize silicon MZM. We first describe the optical link, and the numerical method used for this study. Then we present the results associated to the active region for 1310 nm applications. An analytical model is generated, and allows us to quickly optimize the p-n junction depending of the targeted performances for the MZM. Taking into account the required optical link parameters, the maximum tolerable path losses for different length of MZM is determined. By applying this method, simulations show that the optimum MZM length for 25 Gbps applications is 4 mm with an efficiency of 1.87 V·cm, 0.52 dB/mm of losses. A tolerable path loss of more than 25 dB is obtained

Demonstration and Fabrication Tolerance Study of Temperature-Insensitive Silicon-Photonic MZI Tunable by a Metal Heater

International audienceWe present a temperature-insensitive tunable silicon-photonic Mach-Zehnder interferometer (MZI) filter fabricated by deep ultraviolet lithography. The wavelength shift of the MZI filter depending on temperature is reduced down to -4 pm/degrees C at similar to 1480 nm using a design with waveguide narrowing and widening, and the MZI filter is tunable with a thermal heater at an efficiency of 24 mW/free spectral range (FSR). The FSR of the MZI is about 5.8 nm, which corresponds to a channel spacing of 2.9 nm for a two-channel MZI. We discuss the fabrication tolerance of the fabricated MZI according to experimental and simulation results and show design parameters for a fabrication-tolerant temperature-insensitive MZI with a 20-nm channel spacing for coarse wavelength-division multiplexing application

A Complete Si Photonics Platform Embedding Ultra-Low Loss Waveguides for O- and C-Band

International audienceWe report ultra-low propagation losses in silicon submicrometric waveguides on a 200 mm CMOS compatible photonics platform. We show losses in C-band (O-band) as low as 0.1 dB/cm and 0.7dB/cm (0.14dB/cm and 1.1dB/cm) in monomode rib and strip waveguide geometries, respectively, thanks to a H2 smoothing annealing. In addition to optical losses down to unprecedented levels in silicon waveguides, we show that the performance characteristics of the main passive and active building blocks of the photonics platform are preserved or even improved by the smoothing process

Sub-decibel silicon grating couplers based on L-shaped waveguides and engineered subwavelength metamaterials

International audienceThe availability of low-loss optical interfaces to couple light between standard optical fibers and high-index-contrast silicon waveguides is essential for the development of chip-integrated nanophotonics. Input and output couplers based on diffraction gratings are attractive coupling solutions. Advanced grating coupler designs, with Bragg or metal mirror underneath, low-and high-index overlays, and multi-level or multi-layer layouts, have proven less useful due to customized or complex fabrication, however. In this work, we propose a rather simpler in design of efficient off-chip fiber couplers that provide a simulated efficiency up to 95% (−0.25 dB) at a wavelength of 1.55 µm. These grating couplers are formed with an L-shaped waveguide profile and synthesized subwavelength grating metamaterials. This concept jointly provides sufficient degrees of freedom to simultaneously control the grating directionality and out-radiated field profile of the grating mode. The proposed chip-to-fiber couplers promote robust sub-decibel coupling of light, yet contain device dimensions (> 120 nm) compatible with standard lithographic technologies presently available in silicon nanophotonic foundries. Fabrication imperfections are also investigated. Dimensional offsets of ± 15 nm in shallow-etch depth and ± 10 nm in linewidth's and mask misalignments are tolerated for a 1-dB loss penalty. The proposed concept is meant to be universal, which is an essential prerequisite for developing reliable and low-cost optical couplers. We foresee that the work on L-shaped grating couplers with sub-decibel coupling efficiencies could also be a valuable direction for silicon chip interfacing in integrated nanophotonics

Silicon Photonics for Matrix Switching Applications: Ingredients and Recipes (Invited)

We present an overview of scalable silicon photonic switch matrices. We will describe many different building blocks that can be part of such a system, and the specific architecture proposed in European project IRIS