Introduction

At Meta Connect in September 2024, Meta demonstrated its Orion prototype, which uses Silicon Carbide (SiC) diffractive waveguides to support a 70-degree FOV (see my several articles and videos on Orion). On several occasions, Meta has stated that it hoped Orion’s demonstration of SiC waveguides would encourage further development of the necessary infrastructure and optical-grade SiC, helping to drive down costs. Meta also made the technical case for SiC waveguides at SPIE’s AR/VR/MR conference in January 2025 in their paper The evolution of display materials and processes for full augmented reality.

Several China-based companies, including SEEV, Moldnano, LLVision, and Goeroptics, were likely already developing SiC waveguides before the Orion demonstration and are moving toward production. In the US, Coherent has been developing SiC substrates and promoting their use in AR for some time (see their 2024 article), and Magic Leap has publicly said it is developing SiC waveguides.

As I often say, proponents of a given technology tend to be very vocal about the pros but often leave it to others to speak to the cons. People are often enticed by the pros without considering the cons, i.e., “Too few factors analysis.” In this article, I will try to give a balanced analysis based on what I know so far about SiC waveguides.

At the SEMI Core-Display Conference held on October 29, 2025, Dr. Shi Rui, CTO & Co-founder of SEEV, delivered a keynote speech titled “Mass Production Technology for Silicon Carbide Diffractive Waveguide Chips.” On August 28, 2026, the Nimbo X1 Kickstarter campaign launched. The Nimbo X1 uses a SEEV SiC waveguide (openly admitted by both companies). It was the Nimbo X1 campaign and related YouTube video that inspired me to take a deeper dive into the pro’s and con’s of SiC waveguides.

During the same timeframe as the Nimbo 1 Kickstarter, Radu Reit and I recorded our monthly XR display update, which included an hour-long discussion of SiC waveguides and the Nimbo X1, on our Display Skeptics Patreon channel (https://lnkd.in/gUFkFNeb). Some of the content I generated for this video, along with Radu’s additional technical input, formed the start of this article. Since the video, I have done some additional study of the published articles and my photo library from various conferences.

Speaking of conferences, I wanted to once again say that I will be presenting both a master class and co-hosting a panel session at MicroLED and AR/VR Connect in Eindhoven, September 15-17, 2026. If you are interested, please see the notice at the end of this article.

Moldnano and LLVision Reference Papers

Both Moldnano and LLVision have published informative papers (free to access with the embedded links) on their SiC waveguides work and I have information and figures from these papers. Moldnano and Westlake University published, SiC diffractive waveguides for augmented reality: single-layer, full-color, rainbow-artifact-free display with vision correction (on SpringerOpen eLight – see also the article’s Supplementary material). Moldnano also presented their SiC work at SPIE AR/VR/MR 2026 (SiC diffractive waveguides for augmented reality: Single-layer full-color rainbow-artifact-free display with vision correction). LLVision’s paper is titled, Single-Layer Full-Color SiC Diffractive Waveguide AR Glasses with Large FOV and Rainbow Effect Suppression, published by Photonics in September 2025. I will be citing in the rest of this article from these two sources.

SiC Waveguides Pros (with some Yes-Buts)

The top-cited advantages of SiC are that it has a high refractive index, high thermal conductivity, and toughness against breaking and scratching. Below is a table from a slide that Moldnano and Westlake University presented at SPIE AR/VR/MR 2026.

Note that there are different crystal structures for making SiC, and that optically transparent SiC uses a crystal stacking pattern that repeats every four SiC bilayers with hexagonal symmetry (4H). Moldnano’s 2026 SPIE AR/VR/MR presentation had a slide outlining some of the key material factors.

The main advantage cited for using SiC in waveguides is it high index of refraction. Typical waveguide glass has an index of refraction of 1.7 to 2.0, whereas SiC has an index of refraction of about 2.6. In a diffractive waveguide, this high index supports a wider field of view in a thinner waveguide.

It has been cited by multiple companies, including Meta, Moldnano, and LLVision that using SiC that it better supports full color in a single waveguide. Additionally all three companies have stated that the combination of SiC with their grating design greatly reduces the rainbow capture commonly associated with glass diffractive waveguides.

SiC has very high thermal conductivity. SiC is nearly a thermally conductive as copper or about 200-400 times more thermally conductive as glass. While in theory the thermal conductivity could be used to spread and radiate heat via the surface area of the waveguide, one has to consider that the waveguide will likely be surrounded by other optical coating, films, lenses, dimming structures that will likely be thermally insulating and prevent the heat in the waveguide from radiating. Also as I am about to discuss, SiC is a very brittle material that must be contained for eye safety and likely whatever contains it will be thermally insulating.

SiC is a very tough material that will neither scratch, bend, nor break easily. It’s nearly as scratch-resistant as diamond. Moldnano in the supplement to their paper showed that even a thin SiC waveguide can withstand a typical eye safety ball drop test. But SiC is also brittle, which means that if it breaks, it will have very sharp edges. For eye safety, it should be laminated or otherwise contained. Much of this containment will likely happen due to the other layers of material on either side of the waveguide, including lenses. Also, while the SiC itself is extremely scratch-resistant, it is likely to be covered with material that can scratch much more easily.

SiC is very thermally stable which means that very thin waveguides won’t warp or break with thermal cycling. While generally a good thing, it might be a problem if it is glued to a material that is less thermally stable.

SiC Waveguide Drawbacks

The most obvious drawbacks I see being discussed is the expense of manufacturing raw SiC wafers, the fact that manufacturable SiC wafers are typically small, which limits processing throughput (and adds cost), being crystalline as opposed to amorphous glass, it can have defects and thus lower yield, and the SiC’s toughness, which makes it very hard to polish to a smooth and later to etch diffraction gratings. These drawbacks, one way or another, come back to the cost of manufacturing. Meta and others have stated that with volume production, costs should come down; while this is true, SiC waveguides will inherently be significantly more expensive than their glass-based counterparts.

While the optical advantages are widely discussed by proponents of SiC waveguides, they typically fail to mention serious optical drawbacks. The most serious in terms of image quality is color dispersion, or the fact that the various wavelengths see significantly different indices of refraction, and that the crystal structure of SiC makes it highly birefringent. These two factors make diffractive waveguide design highly challenging. I have seen through two SiC waveguides (Moldnano and Goertek) and seen pictures taken through three others, and the color uniformity is extremely poor compared to other waveguides of similar FoVs (more on this later).

The high refractive index of SiC means inherently worse Fresnel reflections and make anti-reflective coatings more difficult. This in turn means there is more likelihood of visible reflections from the front and ghost images due to reflections.

Trend Toward 2-Grating (WaveOptics-Like) Waveguides

Historically, most diffractive waveguides have used three diffraction gratings: the small entrance grating, a (typically) triangular entrance grating and an exit grating. WaveOptics (bought by Snap in 2021) invented a diffraction grating with two gratings, the entrance grating and a second grating that expands the image and redirects the light to exit.

In the last few years, 2-grating architecture (what Meta calls the “butterfly architecture) seems to be gaining in popularity. Perhaps the most popular uses of the 2-grating approach is in the Even Realties G1 (right) and G2 glasses which use SEEV glass-based 2-grating waveguides. The 2-grating waveguide supports the smaller form factor of the G1 and G2 glasses. I have also noticed that some of the newer Vuzix waveguides have gone to the two grating approach (see below from some pictures I took at CES 2026).

The 2-grating design is much more compact, resulting in a much smaller waveguide, and it eliminates the separate (usually triangular) expansion grating, which is one of the major sources of “rainbow” light capture. However, in my random sampling of various two- and three-grating waveguides over the years, the color uniformity seems seems worse with 2-grating designs. Still, I can’t say if this is an inherent disadvantage of the 2-grating approach.

I’ve also noticed that most 2-grating designs have significantly worse forward-light projection (eye glow) than some of the newer 3-grating designs. However, the Nimbo X1 with the SEEV waveguide and 2-grating waveguides has adopted a pantoscopic (top-to-bottom tilt) that directs the forward-projected light downward. This trick works most of the time, but it can be noticed if the wearer tilts their head back as seen below in the still frames from an Even Realities G1 video that uses a SEEV glass 2-grating waveguide.

Show below is a slide from Meta showing why they chose the “butterfly” type waveguide (upper left); a picture of Moldnano’s SiC waveguide with the more traditional three gratings (upper right); a picture I took of Goeroptics SiC waveguide with 3-gratings, an LLVision diagram showing their two grating design with a linear entrance grating and pillar type expansion and exit grating (lower middle); and a diagram of the SEEV SiC two grating structure (lower right).

While it might not be as obvious, Meta’s Orion used a two sided, two-grating version in the Meta Orion. They had three input gratings to support the combining of monochromatic Red, Green, and Blue MicroLEDs. Please my article Meta Orion AR (Pt. 2 Orion vs Wave Optics/Snap and Magic Leap Waveguides for more details and how it compares to Snap/WaveOptics and Magic Leap concepts.

Poor Color Uniformity from SiC Waveguides Thus Far

The color uniformity of the five diffractive SiC waveguides I have seen, either firsthand or in pictures, is poor. Generally, they are much worse than any glass waveguide I have seen, even from many years ago. It seems that issues like the color dispersion and perhaps the birefringence of SiC are major issues. The five SiC waveguides have different FoVs from 70° to 30° and two use 3-grating designs and three use 2-grating designs. Two of the designs use monochrome MicroLEDs (one combines the color with the waveguide and one with an X-Cube), two use a DLP, and one uses an LCOS display. Regardless of the microdisplay type, number of gratings in the waveguide, or FoV, the color uniformity is abysmal to say the least.

I apologize if this sounds harsh, but it reflects reality. I often discuss what I refer to as the Consumer vs. Technophile curve (illustrated below). This concept suggests that appreciation for image quality is often tied to understanding the effort involved in creating that image. The key point here is that consumers typically do not care about these production details; they are primarily concerned with how a display compares to the TVs and smartphones they already own, which are historically inexpensive but still offer excellent visual quality.

I will freely admit that the camera being “objective” will tend to make color variations seem a bit worse that what the subjective human visual system will see, but it not so different that people will not see these problems. As it turns out, the human visual system can tolerate (not notice) large variations in brightness of a monochrome image. This fact helps with monochrome green glasses in waveguides. But the eye will notice if there are substantial changing in color uniformity across the FOV.

Meta Orion

In October 2024, Meta first publicly demonstrated Orion lab prototype glasses with SiC waveguides, drawing considerable attention to the use of SiC. While Orion has a 70° FOV, it uses individual red, green, and blue 640 x 480-pixel MicroLED displays (by Jade Bird Display). The waveguide had three input gratings to combine the three monochrome displays (see the figure above). With a 70° FoV and only 640×480 resolution, Orion had a very low pixel density of 13 pixels per degree. This limitation was more an issue of the lack of availability of higher-resolution MicroLEDs than of the waveguide, and Meta has said they have high-resolution prototypes.

Meta did not allow people to take pictures, but they did show some images they took at conferences, including the ones below from SPIE AR/VR/MR 2025. As you can see in what is supposed to be a white image, the color uniformity is abysmal. Various colors are dying out at different rates as the cross the waveguide. To be fair in comparison to the other SiC waveguides, Orion had a much bigger FOV and it becomes increasing harder to maintain uniformity as the FoV increases. Still by any measure the uniformity is bad.

Moldnano (and Westlake University)

As stated earlier, Moldnano put out a very information paper, including a interesting supplement, in eLight magazine on their SiC waveguide developments. Their waveguide used a 3-gratings (entrance, expansion, and exit) as shown earlier. Their design is only supporting a 30.82° FOV and is using a 1280×720 DLP. I would not read too much into their use of DLP, as many companies use DLP engines (often using a Coretronics DLP AR projectors which are readily available) for prototyping, and then later switch to LCOS if they make a product as LCOS AR designs are usually smaller and less expensive.

Shown shows a single “white” image (upper left) and shows how the various colors behave across the X and Y FoV.

The article includes several through the the waveguide pictures against a black background (top row) and against some ambient light. It very obvious from the “white” image above and in the pictures below, that the color blue is severely lacking.

SEEV (Nimbo X1)

The Nimbo X1 (from Nimbopearl) using the SEEV SiC waveguide, had a 30° FOV with X-cube MicroLED 640×480. As shown earlier, SEEV uses a 2-grating waveguide. While Nimbopearl won’t say which company’s MicroLEDs they are using, they have confirmed that they are NOT from Jade Bird Display. This would be the first confirmation I have seen of another company being ready to manufacture all three colors of MicroLEDs.

Nimbopearl showed the Nimbo X1 in a YouTube Video and in a video they posted on Reddit in the run-up to their Kickstarter launch. The set of 4 images below were taken from the a from the YouTube video as the text scrolled u the screen. I believe all, or at least most of the text in these images are supposed to be white. As you can see, only a small part in the middle of the FoV is white.

Goeroptics (Subsidiary of Goertek) SiC Waveguide

At SPIE AR/VR/MR 2026, Goeroptics was demonstrating a 50° FOV SiC waveguide with a 1200 x 1560 LCOS panel (taller than wide). As shown earlier, it uses a more conventional 3-grating waveguide. I happened to catch a picture (below right) through the optics of what should have been a mostly white image. Once again, we see the lack of color uniformity.

LLVision

As discussed earlier, LLVision’s paper includes images demonstrating a 50° FOV with a 1280 × 720-pixel DLP. As shown earlier, they use a 2-grating waveguide structure. Of particular interest to me was their use of my 1280 × 720 white-on-black test pattern (below left) from this blog’s test pattern page; only they edited it to take out the two pictures of the elf by cutting and pasting cells 23 and 32 over them, and blacked out my label at the top (see red circles and oval on their image).

Overall, while still poor, their image uniformity seems better than the others. It seems red-deficient and thus has a cyan (blue-green) cast, but at least not as radically varying as the others above.

Conclusion

I want to reiterate the issue: “Too Few Factor Analysis.” It’s easy to see the advantages of SiC, including its high refractive index, high strength, and high thermal conductivity. But these advantages must be weighed against what mitigates them and the issues with SiC waveguides.

What does it matter if the wide FoV has poor image quality? How can you support the wide FoV with enough pixels to make it useful? What about the power consumption associated with supporting a wide FoV with more light, more data, and more processing?

I don’t expect many consumers to be happy with the image quality of the current SiC waveguides in any application, let alone when viewing pictures or videos. It’s unclear how hard it will be to improve color uniformity, but it is likely to be difficult because of the inherent problems caused by dispersion and birefringence.

Given the high cost of making SiC waveguides and the limited potential volume, it’s hard to see how manufacturing issues will be solved and image quality improved enough to satisfy a broad consumer market in the near future. There may be specialized applications where the unique properties of SiC will outweigh it drawbacks.

Curiously, the Nimbo X1 starts with SiC waveguides with only a 30-degree FoV for its first product. It does suggest that SiC manufacturing costs are coming down, but why lead with a more expensive technology they don’t really need? I understand why researchers might start with a smaller FoV as part of development, but not a startup with a product.

Next Time Nimbo X1

When I started this article, I was planning on writing about the Nimbo X1 and the things I had noticed about it. But as I got into studying and writing about SiC, I though the information on the Nimbo X1 got buried. I’m going to try and get the Nimbo X1 article out before I leave for Eindhoven (see below) but it might have to wait until after that MicroLED and AR/VR Connect.

I will be at MicroLED and AR/VR Connect in Eindhoven, Sept. 15-17, 2026 (repeating from last time)

This is my second year attending and presenting at MicroLED and AR/VR Connect in Eindhoven, the Netherlands. I very much enjoyed this conference last year, particularly for the ability to meet people at the several networking sessions. Last year at the conference, I met my Display Skeptics YouTube partner Radu Reit.

On Day-minus-1 of the conference (September 15th) at 10 AM, I’m presenting a 1-hour Master Class on “The Latest Trends in Optical See-Through (OST) AR Hardware and Optics Technology.” The first day, September 15, is Master Classes and Tours of some Local Labs. The conference and exhibition proper are on September 16-17th.

Radu Reit is presenting as a Master Class on “Tearing down smart-glasses to understand the displays & optics driving cost, performance & user experience,” right before me (but in a different room) at 9:00 AM

This year, Radu and I will be hosting a great panel. We will discuss MicroLEDs, LCOS, Lasers, and Micro-OLED for use in AR Light Engines. The Panelist will include Bernard Kress, from Google and SPIE Fellow and past President (and formerly with Microsoft’s HoloLens), Berthold Hahn, from Meta working on MicroLEDs, and Barry Silverstein, from the Center for Extended Reality at the University of Rochester (and until recently Meta), who was a proponent for laser displays.

If you are going to MicroLED and AR/VR Connect this year, hopefully we can meet. Send an email to meet@kgontech.com.

MicroLED and AR/VR connect Discount code

The Conference is offering my readers a €150 discount if they use the discount code KarlARVR. This discount code is valid for both the “Virtual Pass” and “Hybrid Pass” for virtual and/or physical conferences, which can be attended remotely (this blog receives remuneration for the use of this code).