How Photonics Can Enhance Augmented Reality Systems

How AR Has Evolved to Enable the Immersive Internet

AR technology is not a recent invention. Its roots actually date back to 1968, when a Harvard computer scientist, Ivan Sutherland, created an AR head-mounted display system. Commercially, the first AR application appeared in 2008, an advertising application developed in Germany. Today, the potential for AR has broadened. While the gaming industry and those involved in the meta verse have obvious needs for AR systems, the technology also is finding its way into industrial applications, namely to create greater efficiencies. For example, faced with travel restrictions during the COVID-19 pandemic, ASML created an AR solution that enabled its customer support engineers to “visit” its customers’ cleanrooms to help keep their lithography machines serviced and up and running. In the medical field, doctors are using AR for training, to prepare for surgeries, and to access patient vitals.

Writing in Forbes, futurist Bernard Marr projects this to be the year that we encounter more of an “immersive internet,” where technologies like AR and VR usher in a more engaging, collaborative, and interactive online experience. To bring AR systems like glasses into the mainstream to support an immersive internet, engineers will need to address various challenges. One of the toughest is whether it’ll be possible to create glasses that will work for everyone, including people who wear prescription lenses, as well as in any environment, such as a bright, sunny day. But first, designers will need to produce AR glasses that look and feel like the glasses people are accustomed to wearing. So far, the products that are being rolled out carry small improvements, but no one has been able to deliver the Holy Grail. At least not yet. 

How Do Augmented Reality Glasses Work?

AR utilizes optics to create a simulated environment that enhances the real one. AR glasses work in a similar manner to heads-up displays in vehicles, where the simulated content is projected via the glasses in front of the wearer’s eyes. The eyes are essentially the receivers, while the microdisplays or a laser are the light sources and the lenses are the optical elements. The microdisplay light sources can be from organic light emitting diodes (OLED) or liquid crystal displays (LCD). The optical elements combine light from the microdisplays or lasers with light from the real world, projecting augmented information from the microdisplays or lasers onto the real world.

Current designs use light guides to transfer the image created by the source to the eye, with designers using multiple tools to simulate the resulting performance. Along the optical workflow, grating couplers are designed to inject and extract the display image into and out of a light guide, ideally formed by conventional eye wear, using RSoft DiffractMOD™ rigorous coupled wave analysis (RCWA) and FullWAVE™ finite-difference time-domain (FDTD) software. The gratings are added to models in LightTools illumination design software, simulating the radiometric performance to ensure that the wearer can see a clear image with reduced contrast degradation due to stray light. These design iterations are simplified by tool integration as various components are refined and combined along the workflow.

Photonic Integrated Circuits Enable Smallest RGB Laser Module

PICs have gained favor in applications like hyperscale data centers, which benefit from their fast, low-latency data transfer. For AR glasses, PICs provide a way to handle light more efficiently, resulting in lighter, more energy-efficient glasses that can deliver crisp, vibrant, seamless holographic images. Using PICs, BrillianceRGB has developed the smallest and most efficient red, green, and blue (RGB) light source. At 4x7mm² (with 4x4.5mm² being the latest target) and with output power up to 100mW, this solution enables its customers to overcome challenges around miniaturization, integration, energy efficiency, and general comfort for AR projection applications. 

To create the smallest possible RGB laser module, BrillianceRGB uses silicon nitride-based PICs. Photonics and semiconductor development methods have also enabled the team to develop a very scalable manufacturing and packaging process. Its laser chip is placed on its back against other advanced components using “flip chip” technology. The company is now working to turn its existing proof of concept into customer-specific prototypes that integrate with customers’ glasses for volume production. 

BrillianceRGB laser chips are designed using Synopsys OptoDesigner, a solution many of its veteran engineers are deeply familiar with having used it since their university days. The tool’s algorithmic module helps engineers design and optimize photonic components, waveguides, and complete chips. In PICs, waveguides confine and direct the flow of light energy and, when well designed, will provide an efficient combination and transmission of the red, green, and blue colors. With the OptoDesigner solution, BrillianceRGB achieved first-time-right waveguide routing, saving time and effort thanks to the solution’s built-in photonic aware algorithms. OptoDesigner is now fully integrated with Synopsys OptoCompiler, the industry’s only unified electronic and photonic design environment, with support for simulation, layout, and verification of PICs. OptoCompiler is also used to design and optimize meta-surfaces for AR applications.