This PDF file contains the front matter associated with SPIE Proceedings Volume 12005, including the Title Page, Copyright information, Table of Contents, and Conference Committee listings.

Silicon-on-insulator (SOI) substrate technology has been the defining foundation of silicon photonics integrated circuits over the last 20+ years, fostering its commercial success in datacenter interconnects and promoting widespread adoption for high-speed optical transceiver products. More recently, novel applications could also leverage the silicon photonics toolset and ecosystem maturity to target newer, expanding markets, including consumer sensing for healthcare monitoring devices, LiDAR devices for the automotive, as well as optics-based advanced quantum computing and neural networks.

In such dynamic context, Photonics-SOI substrates design and the underlying Smart-Cut process need to relentlessly adapt in order to meet the evolving requirements of end-products and applications specifications, while addressing industrial high-volume manufacturability, high fabrication yields, cost-effectiveness, and related quality constraints. More specifically, the need for growing aggregated bandwidth density at low power dissipation in transceivers products as well as the integration of increasingly complex optical functions for sensing applications, are driving towards more stringent requirements in terms of top silicon layer within-wafer and wafer-to-wafer uniformity, atomic-scale surface roughness, low defect density and improved crystalline material quality. In this paper, the authors report on technological advances in the 300-mm Photonics-SOI process, while benchmarking these on a 300-mm silicon photonics multi-project wafer (MPW) process run. Notably, an extensive set of silicon photonics devices and circuits will be fabricated on a matrix of 220-nm-thick 2-μm-buried oxide Photonics-SOI substrates using different Smart-Cut process windows, with optical characterization data and device performance supporting the ultimate choice of substrate technology for silicon photonics process design kits on thin-SOI platforms.

The biggest barrier for many scientific and commercial applications in communications, spectroscopy, life sciences, food safety, biomedicine as well as industrial metrology is the lack of appropriate sources and detectors of THz radiation with enough power and sensitivity with small footprints and portability. Currently available photonic based THz systems have already demonstrated great potential in terms of high tunability, standard room temperature operation, and signal quality, however they are still suffering from many drawbacks, such as big size equipment (needs an optical table), mechanical disturbance (additional to noise and alignment), high power consumption (electrical and optical), and low flexibility system (each application needs a new setup). We therefore propose a new THz system platform, aimed to overcome all the above drawbacks, based on photonic integrated circuits (PICs) and nanotechnology.

Silicon nitride (SiNx), has been widely regarded as a CMOS photonics enabling material, facilitating the development of low-cost CMOS compatible waveguides and related photonic components. We have previously developed an NH3-free SiN PECVD platform in which its optical properties can be tailored. Here, we report on a new type of surface-emitting nitrogen-rich silicon nitride waveguide with antenna lengths of L < 5 mm. This is achieved by using a technique called small spot direct ultraviolet writing, capable of creating periodic refractive index changes ranging from -0.01 to -0.04. With this arrangement, a weak antenna radiation strength can be achieved, resulting in far-field beam widths < 0.0150, while maintaining a minimum feature size equal to 300 nm, which is compatible with DUV scanner lithography.

The anticipated feature of future generation remote infrared (IR) sensing and imaging technologies includes adding so called multi-colour capabilities. Such enhancement of the current state-of-the-art IR detector and imaging focal plane array (FPA) technologies allows real-time spectral information to be gathered from multiple wavelength bands. Multi/hyper-spectral imaging results in improved target recognition and is applicable to numerous remote sensing spectroscopy/imaging applications. In order to provide a reduced size, weight and power (SWaP) solution, a micro electromechanical systems (MEMS) based electrically tuneable adaptive filter technology has been developed for important IR bands of the electromagnetic spectrum. The adopted approach is capable of delivering on-chip remote hyper/multi-spectral sensing by obtaining narrow-band spectral sensitivity utilising a tuneable MEMS optical filter fabricated directly on a detector. This paper summarizes the performance demonstrated within the most technologically relevant bands of short-wave IR (SWIR, 1.4-2.5 µm), mid-wave IR (MWIR, 3-5 µm), and long-wave IR (LWIR, 8-12 µm). In SWIR, the demonstrated nanometer-scale uniformity in the flatness of suspended MEMS allows for spatial uniformity of the filtered peak centre wavelength and the achieved 30-35 nm spectral width to remain within single nanometers over 500µm x 500µm optical apertures. In LWIR, the spatial peak wavelength selectivity variation is achieved to be less than 1.2% across 200μm × 200μm optical imaging areas, exceeding the requirements for passive multispectral thermal imaging and validating the suitability for mechanically robust multi/hyper-spectral remote sensing and imaging applications deployable on low-SWaP field-portable platforms.

We present a novel technology wherein memristors are heterogeneously integrated with optoelectronic devices on a silicon photonic platform. We present results on memristor integrated microring modulators and lasers with non-volatile memory. Furthermore, multiple devices are combined with optical waveguides to create photonic integrated circuits with neuromorphic computing. By pairing non-volatile memory devices directly with silicon photonics, we can integrate memory, computing, and high-speed optical interconnects all together on the same chip.

Extensive literature has shown that finite impulse response (FIR) interferometers can be engineered to be insensitive under variations of different physical parameters, e.g., to ensure flat-top response and/or tolerance to fabrication errors. In this context, I will show how the Bloch sphere representation can be a very powerful design tool providing superior physical insight into the working principle of autocorrective devices like broadband 50:50 splitters or flat-top interleavers, that can be therefore designed through simple analytical formulas. I will eventually review the recent progress in practical implementation of the autocorrective designs in the micron-scale silicon photonics platform of VTT.

We propose a Machine Learning (ML) based approach to calculate the control signals to apply to an integrated Optical Phased Array (OPA) to get the desired far field profile, which is of particular interest for single-pixel imaging applications. We validated this approach considering a 1D OPA with 8 thermally controlled input waveguides and an 8x1 combiner. We generated 7500 random combinations of the 8 control signals, performing BPM simulations in Synopsys RSoft to calculate far field intensity maps later used to train in MATLAB the ML algorithm. The trained network can then generate the control signals required to obtain any desired far field pattern.

We present our work to extend silicon photonics with MEMS actuators to enable low-power, large scale programmable photonic circuits. For this, we start from the existing iSiPP50G silicon photonics platform of IMEC, where we add free-standing movable waveguides using a few post-processing steps. This allows us to implement phase shifters and tunable couplers using electrostatically actuated MEMS, while at the same time maintaining all the original functionality of the silicon photonics platform. The MEMS devices are protected using a wafer-level sealing approach and interfaced with custom multi-channel driver and readout electronics.

Subwavelength grating metamaterials have become an integral design tool in silicon photonics. The lithographic segmentation of integrated waveguides at the subwavelength scale allows us to control optical properties such as mode delocalization, wavelength dispersion, and birefringence. So far, a range of subwavelength-based devices with unprecedented performance has been demonstrated, such as couplers, polarization-handling structures, filters, and input/output chip interfaces. In this invited talk, we will review the anisotropic foundations of subwavelength-grating metamaterial design and will provide an overview of our latest advances in subwavelength-enhanced silicon photonics devices, including optical antennas for beam steering and multi-line Bragg filters for spectral shaping.