# Integrated Photonics for IoT, RoF, and Distributed Fog-Cloud Computing: A Comprehensive Review
## 7 Industry Implementations
Programmable photonic circuits can be viewed as optical analogues of electronic Field-Programmable Gate Arrays (FPGAs), enabling dynamic reconfiguration and multifunctionality for photonic applications [93]. Unlike traditional fixed photonic integrated circuits, these systems can adapt their functionality post-fabrication, enabling multiple operations such as signal routing, modulation, and filtering on a single chip. This programmability drastically reduces development time, lowers manufacturing costs, and enhances scalability, making them especially advantageous in applications requiring flexible analog processing such as telecommunications, data centers, quantum information systems, and artificial intelligence. Furthermore, programmable photonic circuits incorporate self-configuration capabilities, mitigating the effects of fabrication imperfections and environmental variations through intelligent control algorithms [93]. Figure 12 illustrates the integrated photonic hardware and associated electronic control architecture used in multipurpose programmable photonic circuits. Panel (a) highlights the growing complexity of state-of-the-art photonic integration, characterized by the increasing number of integrated phase shifters. Panel (b) depicts the general architecture of a field-programmable photonic gate array (FPPGA), featuring a programmable waveguide mesh core surrounded by specialized high-performance building blocks and optical input/output ports. Panel (c) provides a detailed view of the FPPGA core, implemented with a longitudinally parallel hexagonal waveguide mesh interconnection topology. The electronic control subsystem, shown in panel (d), includes essential elements such as a driving subsystem for configuring the waveguide mesh, an optical monitoring subsystem for feedback, and software algorithms for auto-routing and self-configuration. Lastly, panel (e) conceptually represents the comprehensive scattering matrix that characterizes the input-output relationships across both spatial and spectral domains within the FPPGA core, enabling detailed system-level programming and optimization. Meta (formerly Facebook) and Microsoft are advancing integrated photonics to overcome the limitations of traditional pluggable optical modules in data center interconnects (DCIs). Meta promotes the co-packaging of optics with switch electronics to reduce power consumption by 20% and improve scalability via automated manufacturing processes compatible with CMOS technology [94]. Complementing this, energy-proportional data center architectures co-designed at the system and photonic levels allow for optical paths to be activated dynamically based on traffic needs--achieving up to 60% energy savings in optical transceivers while sustaining performance [95]. These strategies align well with the dynamic and variable workloads inherent in Fog computing. Microsoft has also collaborated with optical foundries to develop silicon photonics-based multi-wavelength transceivers and is exploring neuromorphic photonic processors for future acceleration workloads in edge-cloud environments [96]. Additionally, both companies contribute to open-source hardware initiatives for photonic-electronic co-packaged modules to promote industry-wide standardization and supply chain diversity [97]. Amazon Web Services (AWS) is also actively investing in integrated photonics. In collaboration with STMicroelectronics, AWS developed a photonics chip designed to boost internal bandwidth and reduce power consumption in AI data centers [98]. By replacing conventional electrical data transmission with light-based interconnects in transceivers, AWS targets lower latency and energy use at massive scale. The chip is expected to enter deployment later this year, with production based in STMicroelectronics' Crolles, France facility. This marks a significant milestone in moving toward more sustainable and high-performance distributed computing infrastructure.