Gerald Dahlmann | Coherent: How can you slash the power consumption of AR sensors without sacrificing performance?
00:07:52 - 00:09:58
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How can you slash the power consumption of AR sensors without sacrificing performance?
Two key strategies exist for drastically reducing the power consumption of 3D sensing modules in AR/VR devices. The first is the adoption of multi-junction VCSEL technology. This involves epitaxially stacking several quantum wells on top of each other, separated by tunnel junctions, and operating them in series. This architecture allows a single electron to generate multiple photons, significantly increasing peak power and enabling shorter pulses, which improves the signal-to-noise ratio (SNR) for a given amount of power. While up to eight junctions have been demonstrated, the practical sweet spot is around two or three junctions due to the trade-off with increasing operating voltage.
The second approach is a strategic shift to longer infrared wavelengths for illumination. Most current systems operate at 940 nm, but moving to wavelengths like 1130 nm or 1380 nm offers considerable advantages. These specific wavelengths coincide with significant dips in the solar radiation spectrum, meaning there is far less ambient background light to compete with. This allows the sensor to achieve the same SNR with much lower output power from the illuminator, directly translating to power savings.
This move to longer wavelengths provides additional benefits beyond power reduction. It offers a greater margin for eye safety, a critical consideration for near-eye devices, and makes the sensing system inherently more robust when used in bright, outdoor sunlight. While the light sources are available, this shift requires a corresponding evolution in sensor technology. An emerging ecosystem, including silicon-germanium (SiGe) and quantum dot-based image sensors, is developing to provide the necessary sensitivity at these longer wavelengths, paving the way for next-generation, low-power sensing.
In this short video, you can learn:
* The principle of multi-junction VCSELs for higher quantum efficiency.
* Why moving to wavelengths like 1130nm or 1380nm drastically improves signal-to-noise ratio.
* The emerging sensor ecosystem that will enable this long-wavelength shift.
📋 **Clip Abstract** Learn two advanced strategies to dramatically reduce the power consumption of 3D sensing modules for AR glasses. Discover how multi-junction VCSELs and a strategic shift to longer infrared wavelengths can improve performance and battery life.
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#MultiJunctionVCSELs, #LongWavelengthIR, #SiGeSensors, #QuantumDotSensors, #ARElectronics, #WearableElectronics
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MicroLEDs, AR/VR Displays, Micro-Optics 2025: Innovations, Start-Ups, Market Trends
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00:12:32 - 00:14:35
What single material property is the biggest bottleneck for wide field-of-view AR, and what's the ultimate solution?
What single material property is the biggest bottleneck for wide field-of-view AR, and what's the ultimate solution?
The fundamental limit to achieving a wide field-of-view (FoV) in a waveguide display is the refractive index of the waveguide material itself. This relationship is governed by Snell's Law; for light to be guided via total internal reflection (TIR) over a wide range of angles, the material must have a high refractive index. Common materials like polymers and high-index glasses, with refractive indices in the range of 1.7 to 2.0, are reaching their physical limits and cannot support the truly immersive, wide FoV experiences required for next-generation AR.
To break past this barrier, the industry is turning to single-crystal materials. While options like Lithium Niobate offer a higher index of 2.3, Silicon Carbide (SiC) has emerged as the ultimate material with an exceptionally high refractive index of 2.7. This property is the key enabler for a significant leap in performance, as demonstrated by Meta's prototype which achieved a 70-degree, full-color FoV in a single-layer waveguide—a feat unattainable with conventional glass or polymer optics.
Silicon Carbide's suitability for AR waveguides extends far beyond its refractive index. It possesses excellent optical transparency for high-brightness displays, is extremely hard and scratch-resistant, and has superior mechanical strength, making it far more durable than glass. Furthermore, SiC can be processed to achieve very low Total Thickness Variation (TTV), which is critical for maintaining image quality across the waveguide. Crucially, a mature, large-scale manufacturing ecosystem for SiC already exists, established by the power electronics industry, providing a foundation for volume production.
In this short video, you can learn:
* How Snell's Law dictates the maximum field-of-view in a waveguide.
* A comparison of waveguide materials, from polymers to Silicon Carbide (SiC).
* The unique combination of optical, mechanical, and manufacturing properties that make SiC ideal for AR.
📋 **Clip Abstract** Discover why Silicon Carbide (SiC) is poised to revolutionize AR displays by enabling a much wider field of view. This clip explains the physics linking refractive index to FoV and details the unique properties that make SiC the ultimate waveguide material.
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#SiliconCarbideWaveguides, #ARFieldOfView, #HighRefractiveIndex, #TotalInternalReflection, #WearableElectronics, #MicroLEDDisplays