Silicon photonics | EPFL Graph Search

Silicon photonics is the study and application of photonic systems which use silicon as an optical medium. The silicon is usually patterned with sub-micrometre precision, into microphotonic components. These operate in the infrared, most commonly at the 1.55 micrometre wavelength used by most fiber optic telecommunication systems. The silicon typically lies on top of a layer of silica in what (by analogy with a similar construction in microelectronics) is known as silicon on insulator (SOI). Silicon photonic devices can be made using existing semiconductor fabrication techniques, and because silicon is already used as the substrate for most integrated circuits, it is possible to create hybrid devices in which the optical and electronic components are integrated onto a single microchip. Consequently, silicon photonics is being actively researched by many electronics manufacturers

Linear Electro-optic Effect in Silicon Nitride Waveguides Enabled by Electric-Field Poling

Camille Sophie Brès, Edgars Nitiss, Anton Stroganov, Boris Zabelich

Stoichiometric silicon nitride (Si3N4) is one of the most mature integrated photonic platforms for linear and nonlinear optical applications on-chip. However, because it is a centrosymmetric material, second-order nonlinear processes are inherently not available in Si3N4, limiting its use for multiple classical and quantum applications. In this work, we implement thermally assisted electric-field poling, which allows charge carrier separation in the waveguide core, leading to a depletion zone formation and the inscription of a strong electric field reaching 20 V/mu m. The latter results in an effective second-order susceptibility (chi((2))) inside the Si3N4 waveguide, making linear electro-optic modulation accessible on the platform for the first time. We develop a numerical model for simulating the poling process inside the waveguide and use it to calculate the diffusion coefficient and the concentration of the charge carriers responsible for the field formation. The charge carrier concentration, as well as the waveguide core size, is found to play a significant role in determining the achievable effective nonlinearity experienced by the optical mode inside the waveguide. Current findings establish a strong groundwork for further advancement of chi((2))-based devices on Si3N4.

AMER CHEMICAL SOC2022

Integration of MEMS in Silicon Photonics

Alain Yuji Takabayashi

Like integrated electronics, integrated photonics such as Silicon Photonics benefit from increased device-density on a single chip. Silicon is an excellent material for integrated photonics because its high refractive index allows devices to be made small, and the established silicon CMOS fabrication infrastructure provides a convenient route towards scaling up production. However, standard Silicon Photonics faces a bottleneck in scaling up device-density due to excessive power consumption and high optical losses associated with individual devices. Microelectromechanical systems (MEMS) provide a unique solution to this problem by providing a physical redistribution of optical media to perform the necessary active functions in photonic integrated circuits (PICs) with minimal power consumption and low loss.This thesis tackles two important aspects needed for implementing large-scale MEMS-enabled PICs in silicon. First, the required microfabrication processes are developed for the first-time, by full process integration of MEMS in an established foundry platform, the Interuniversity Microelectronic Centre's (IMEC) iSiPP50G Silicon Photonics technology. By demonstrating MEMS-compatibility, the barrier to adopting this new technology is reduced, and the devices and circuits themselves benefit from co-integration with high-performance standard components. Second, a new class of electrostatic MEMS-enabled photonic building blocks are designed, simulated, and experimentally characterized. Demonstrated devices include a set of remarkably broadband (bandwidth > 80 nm) tunable couplers capable of continuous optical power tuning between output ports to produce extinction ratios greater than 20 dB with minimal insertion loss (reaching < 0.4 dB). In terms of switching, a very low-voltage, six-port count device and a particularly compact (65 um x 62 um) photonic MEMS switch with sub-microsecond switching time are also presented. Further MEMS-enabled functionality is demonstrated with a wavelength-selective add-drop filter and a discussion of phase-shifters and multi-device sub-circuits. These components can be repeated and combined with one another to create complex and reconfigurable networks, and therefore represent an essential stepping stone towards the realization of very large-scale PICs. Together, these key developments in microfabrication and device design promise PIC designers MEMS-enabled photonic components as standard elements in their circuits to efficiently implement functions such as switching, tuning, and filtering for application in photonic switch matrices, weighted interconnects for neural networks, and programmable PICs.

EPFL2021

Systems and devices in a 30 GHz silicon-on-insulator platform

Christophe Marcel Georges Galland, Zhang Yi

We present a 30 GHz silicon photonic platform that includes low-loss passive components, high-speed modulators and Ge-on-Si photodetectors. The platform is available to the community as part of the OpSIS-IME multi-project-wafer foundry service. We conclude with a proposal for a fully CMOS-compatible optical isolator based on multistage phase modulation.

Institution of Engineering and Technology2013

Integration of MEMS in Silicon Photonics

Alain Yuji Takabayashi

EPFL2021