Notes on High-Energy Lasers and SiC Optical Components —  Surface Processing Techniques

Why Silicon Carbide for High-Energy Laser Optics?

Silicon carbide (SiC) crystals can withstand temperatures up to 1600 °C, possess high hardness, exhibit minimal deformation at high temperatures, and offer excellent transparency from visible red light to infrared wavelengths. These properties make SiC an ideal material for high-power laser modules, optical reflectors, collimating optics, and transmission windows.

Changing Landscape of High-Energy Laser Design

In the past, most high-power laser systems were based on ultrashort-pulse fiber lasers or large-scale reflector-based focusing lasers. However, these setups often suffered from limited beam directionality, energy density, and thermal loading.

Recent trends in laser system development demand:

• Higher energy outputs
• Long-range beam propagation
• Tighter beam divergence and collimation
• Lightweight and compact optical modules

SiC-based optics are now gaining traction as a solution to these evolving requirements—enabled by recent progress in crystal growth and ultra-precision fabrication technologies.

SiC Optics: From Theory to Application

With the maturation of SiC component processing—and even diamond crystal optics beginning to emerge—the future looks promising for industrial-scale deployment.

Crossroads with AR Optics and Nanostructuring Challenges

The microfabrication challenges in SiC laser optics are remarkably similar to those in SiC-based AR waveguides:

All on 4-inch / 6-inch / 8-inch SiC wafers with:

• Creating anti-reflective (AR) nanostructures
• Enhancing transmission or reflection efficiency
• Patterning sub-wavelength grating structures
• 100–500 nm periodicity
• Nanometer-scale depth precision

Not easy tasks—especially on a material as hard and chemically inert as SiC.

Global Research Landscape

Institutions like Westlake University, Harvard, and others have started exploring this field.

One of the biggest hurdles?
Even if the SiC wafers are affordable, how do you etch sub-micron periodic nanostructures on such a hard material without destroying it?

Throwback: Etching SiC a decade ago

Over a decade ago a 4-inch SiC wafer cost over 10,000 RMB, and etching even one was a painful process. But guess what? It worked.

We achieved sub-wavelength anti-reflective (AR) structures on SiC that reduced surface reflectance by more than 30%—without using any photolithography tools.