It is now well established that silicon nitride offers many advantages for integrated nonlinear photonics. Pushed by recent progress in fabrication, we now have access to very low loss waveguides while maintaining large flexibility in terms of dispersion engineering, both essential for the design of efficient nonlinear systems. As such many nonlinear optical demonstrations, mainly based on third order effects in the telecom band, have been performed. Pushing the applications over the entire accessible spectral range of silicon nitride, from the visible to the middle infrared, as well as offering completely new horizon of applications by inducing effective second-order effects, would provide new and essential element to nonlinear integrated photonic toolbox. In this talk I will review progress in reaching the middle infrared for sensing applications as well as leveraging all-optical poling to enhance the typically weak second-order nonlinearities of the platform.

Many life-threatening diseases can be prevented or treated better if only the methods to diagnose or monitor or treat them would be more directly accessible and more affordable to the patient. The COVID-19 pandemic shows that rapid testing is of key importance for infectious diseases. But also other major diseases (cardiovascular, diabetes, cancer, neurodegenerative diseases…) can benefit immensely from cost-effective techniques that can be used in a point-of-care setting or even directly by the patient. Electronic ICs have played a key role in medical devices for many years. Photonic ICs are joining in and bring added value and functionality for a broad range of medical diagnosis and therapy. Silicon photonics stands out as a key enabler since it builds on the maturity of the silicon technology world while offering a rich variety of sensing modalities in an ultra-compact footprint. In this talk I will discuss several examples of proof-of-concept medical devices implemented by means of silicon or silicon nitride photonic ICs, both for in-vitro and in-vivo applications.

Mid-infrared (mid-IR) spectroscopy is a nearly universal way to identify chemical and biological substances, as most of the molecules have their vibrational and rotational resonances in the mid-IR wavelength range. The development of silicon-based mid-IR photonic circuits has recently gained a lot of attention. Among the different materials available in silicon photonics, germanium (Ge) and silicon-germanium (SiGe) alloys with a high Ge concentration are particularly interesting because of the wide transparency window of Ge extending up to 15 µm. In this work we will review recent results in the development of photonics circuit based on Ge-rich SiGe waveguides.

Presentation on Programmable Integrated Photonics for the Emerging Applications in Silicon Photonics conference, SPIE Photonex and Vacuum Expo 2020

The scaling up of silicon photonics towards densely integrated architectures is enabling new optical functionalities and is creating opportunities for emerging applications. This evolution needs to be accompanied by adequate tools for the control of more complex architectures. We report on latest advances on the monitoring and automatic calibration of photonic integrated circuits, self-configuration and tuning of programmable photonic structures, stabilization and locking of the working point against environmental fluctuations. Several strategies are illustrated which may can be used for different circuit topologies, like general-purpose meshes of Mach-Zehnder interferometers and coupled-resonator filters, and can self-adapt to the specific optical signals. Examples of applications are presented in the field of optical signal processing, wavelength-division and mode-division-multiplexing optical communication systems, and free-space-optics imaging.

The integration of mid-IR lasers with Si-based platforms is needed for the development of smart sensor grids. Here we review our recent results on GaSb-based laser diodes (LDs) and InAs/AlSb quantum-cascade lasers (QCLs), grown on on-axis (001) Si substrates by molecular-beam epitaxy, and covering emission wavelengths from 2 to 10 µm. Threshold current densities well below 1 kA.cm-2 are achieved in both cases. Ridge LDs operate cw up to 80 °C and emit around 10 mW at room temperature whereas QCLs exhibit performances comparable to their counterpart grown on native InAs substrates. In addition, we will demonstrate that etching facets is a viable route toward cavity definition.

Presentation: "Suspended silicon waveguide devices for mid-infrared sensing undefined" for the Emerging Applications in Silicon Photonics conference of the SPIE Photonex and Vacuum Expo 2020

We present here a photonic chip based axicon like lens that has a 850 um long central lobe, with a diameter of 5.7 um. The 1.52 mm x 1.38 mm device consists of circular grating with a novel azimuthal apodization to increase light penetration depth by an order of magnitude and multiple stages of 1x2 multimode interferometer splitters/combiners. We characterize the axicon with a swept source laser (1300 +/- 50 nm) coupled in with a GRIN lens onto the device, with the light out-coupled from a regular grating coupler. We also characterize the spectral performance of the device, using balanced homodyne detection to resolve the power, and show that the position of the central lobe does not vary significantly with wavelength.

Welcome and Introduction to Conference 11577: Emerging Applications in Silicon Photonics