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With the rapid advancement of artificial intelligence (AI), augmented reality (AR) glasses are becoming a hot topic in the smart device field. The fusion of AI and AR allows these glasses to not only provide richer immersive experiences but also perform more intelligent tasks. However, as AI and AR functionalities continue to merge, traditional optical materials like glass and resin face increasing limitations, particularly in terms of field of view (FOV), weight, battery life, and display quality. To break through these bottlenecks, Silicon Carbide (SiC), a wide-bandgap semiconductor material, has emerged as a core component for AR glasses, bringing several innovative opportunities.

Challenges and Demands for AR Glasses

The goal of AR glasses is to provide a lightweight yet high-performance visual experience. However, many AR glasses currently on the market still rely on traditional optical materials, such as glass or resin, for waveguide technology. While these materials can meet basic display needs, they gradually expose issues as the functionality of the devices increases. Problems like narrow field of view, rainbow effects, heavier weight, and shorter battery life become more pronounced as the demands for AI and AR integration rise.

One particularly troubling issue is the rainbow effect in full-color displays. This phenomenon occurs when ambient light passes through the AR waveguide, splitting into rainbow-colored light. This effect is caused by the diffraction of light at different wavelengths and severely affects the user’s visual experience, limiting the potential of AR glasses.

Silicon Carbide: A Breakthrough Solution

Silicon carbide (SiC) has emerged as a promising solution to address these issues, thanks to its high refractive index and excellent thermal conductivity. SiC's unique properties offer several significant advantages for AR optical displays.

1. Wider Field of View

Silicon carbide boasts a refractive index of over 2.6, much higher than conventional glass and resin materials. This higher refractive index allows SiC to enable a significantly larger field of view in AR glasses. Traditional waveguides typically offer only a 40-degree FOV, while a single layer of SiC can achieve an FOV of over 80 degrees, greatly expanding the user’s visual experience.

2. Solving the Rainbow Effect

The rainbow effect, which results from the diffraction of light through waveguides, is a major pain point in AR glasses. The high refractive index of SiC allows light to be compressed within the material, reducing the wavelength spread. This minimizes the diffraction period of the grating, which makes the rainbow effect invisible to the human eye. As a result, SiC waveguides offer clearer, more natural visual experiences with less interference from ambient light.

3. Longer Battery Life and Stable Performance

The processing and display modules in AR glasses generate a significant amount of heat. Traditional materials like glass and resin are not efficient at dissipating this heat, which can lead to overheating and degraded performance. SiC’s thermal conductivity, which is around 490 W/m·K, far exceeds that of glass (around 1 W/m·K) and resin, allowing it to effectively conduct heat away from the components. This ensures stable performance, even under high-brightness displays, such as those with peak brightness levels up to 5000 nits, and extends battery life by preventing overheating.

4. Simplified Thermal Design

In traditional AR glasses, cooling is often managed through complex heat dissipation modules or active cooling systems, which add weight and complexity to the device. SiC’s high thermal conductivity allows for passive heat dissipation directly from the waveguide material itself, eliminating the need for bulky cooling systems. This makes it possible to reduce the weight and complexity of the device while enhancing its overall integration and efficiency.

Domestic Technological Innovation: Paving the Way for SiC Application

As the demand for high-performance AR glasses grows, the integration of SiC into optical systems has become a key area of focus. However, applying SiC as a waveguide substrate in AR glasses requires overcoming several technical challenges, particularly around manufacturing and processing.

While SiC has been widely used in power semiconductors, its application in AR glasses is still in the developmental stage. In 2020, when the Meta team finalized their decision to use SiC waveguides for their AR glasses, they faced a global shortage of equipment and processes for producing "optical-grade SiC." To address this, they collaborated with wafer manufacturing companies to develop etching equipment and processes suitable for mass production, creating a complete production line to unleash SiC's full potential.

In China, the country’s strong presence in both the display industry and wide-bandgap semiconductor technologies has laid a solid foundation for the large-scale application of SiC in AR displays. As the world's largest producer of display panels and a key player in the development of wide-bandgap semiconductor devices, China is advancing both research and manufacturing processes in the field. Chinese universities and enterprises are working on technological innovations across SiC waveguide design, manufacturing, and packaging, which will help accelerate its adoption in AR glasses.

Conclusion

Silicon carbide has introduced a revolutionary change to the optical technologies used in AR glasses. From expanding the field of view to solving the rainbow effect, improving battery life, and simplifying thermal design, SiC has proven to be a game-changer in enhancing the performance and user experience of AR glasses. As relevant technologies continue to evolve, AR glasses will soon move beyond science fiction and become a practical, indispensable tool for everyday life.