August 25, 2025 by Jeff Shepard
Collected at: https://www.eeworldonline.com/what-are-the-applications-for-photonic-integrated-circuits-on-the-edge-2/
Photonic integrated circuits (PICs) can enable high-speed data transmission, low-power consumption, and compact size, making them suitable for integration into edge devices. They are increasingly being used in signal processing for edge AI and sensor applications.
Silicon photonics is an expansive technology. It’s based on CMOS processing, heterogeneous integration, and advanced optical functionality. Silicon-on-insulator (SOI) is a key enabler. Some of the key elements of PICs include (Figure 1).
- Optical waveguides can be made with silicon or silicon nitride and enable efficient on-chip optical connectivity.
- Optical ring resonators are a basic building block and can be used with optical filters, modulators, multiplexers, and frequency comb generators. There are also more specialized designs like Fabry-Perot Resonators for lasers and interferometers, and Whispering Gallery Mode Resonators that are optimal for sensing and non-linear optics functions.
- Modulators are used to manage photonics properties like phase, polarization, and intensity to optimize PIC performance.
- Photodetectors provide connectivity between the optical and electrical sections of PICs and the outside.
- Optical coupling elements are used to combine, split, or redistribute optical signals. Grating couplers and edge couplers are the most common due to their unique advantages. Grating couplers are compatible with CMOS processing, while edge couplers require additional back-end processing steps like cleaving and polishing, but can provide connectivity to external lasers and electronics.
Figure 1. Examples of common PIC functional elements. (Image: Santec)
PICs in edge AI
PICs can support lower latencies for applications like LIDAR in autonomous vehicles and robots, enabling safer navigation. PICs consume significantly less energy than conventional ICs, an important consideration in energy-constrained edge devices.
Further energy savings can be realized since processing data on the edge device reduces the need for cloud connectivity and the associated energy requirements. Eliminating or minimizing the need for wireless connectivity also makes edge devices more resilient.
PICs in advanced sensors
PICs can be used in highly sensitive and compact sensors for edge applications. PICs combined with edge AI can implement real-time object and facial recognition, as well as other complex image processing functions, on the sensor chip.
PIC sensors are being used for environmental monitors that can detect pollutants and measure air or water quality. They are also used in food processing to measure parameters like ripeness and nutrient content.
PIC lab on a chip
PIC sensors can enable rapid diagnostics of medical and environmental conditions in the field, without relying on remote laboratories. In many cases, they also have higher sensitivities and provide superior results. For some materials, attomolar concentrations, 10-18 moles per liter, or one quintillionth of a mole of a substance dissolved in one liter of solution, can be reliably detected with PIC sensors.
Integrated optical sensors for these applications are usually fabricated using silicon nitride (SiN). SiN waveguides have good sensitivity over the visible to near-infrared range and can be fabricated with a small bend radius. That enables a very long sensor to be “rolled up” so it occupies very little space on the surface of a PIC. Longer sensors have higher sensitivity.
Some designs have a coating on the sensor that changes its refractive index when it encounters the target molecules. Changes in the refractive index are picked up using photonic transducers and connected to the rest of the lab on a chip using optical waveguides (Figure 2).
Figure 2. Lab-on-a-chip biosensors like this, based on PICs, can provide real-time data for medical diagnostics. (Image: Aventier)
Other photonics platforms
PICs are a versatile technology and can be made with materials beyond Si and SiN. Many PICs incorporate silica (SiO2) for functions like planar optical waveguides.
Figure 3. This tunable laser system uses hybrid integration with a low-loss SiN PIC and a high-performance active gain InP PIC. (Image: PhotonDelta)
Lithium Niobate (LiNbO3) can be used for making low-loss modulators. Its low optical index and broad transparency window make it well-suited for matching fiber input-outputs. Lithium Niobate on Insulator (LNOI) technology is under development for future PIC designs.
System cost and performance can be simultaneously optimized by mixing PIC technologies using heterogeneous or hybrid integration. For example, a tunable laser system has been developed for military systems that combines a low-loss SiN PIC with a high-performance active gain Indium Phosphide (InP) PIC (Figure 3).
Summary
PICs are being used in a growing variety of edge applications, such as data processing and sensors. They can reduce energy consumption and increase processing capabilities, and can be implemented on single chips or using heterogeneous integration, incorporating multiple semiconductors and sensor technologies.
References
Designing a Photonic Integrated Circuit: Best Practices for Simulation & Layout, SimuTech
Exploring Photonic Integrated Circuits and Optical ICs, Avantier
High-performance analog signal processing with photonic integrated circuits, Light Science and Applications
Introduction to Silicon Photonics, Santec
Photonic Computing Takes a Step Toward Fruition, APS Physics
Photonic Integrated Circuit (PIC), AyarLabs
What is a Photonic Integrated Circuit?, Ansys
What is a Photonic Integrated Circuit?, PhotonDelta
What is Integrated Photonics?, AIM Photonics
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