High-power CO ₂ lasers operate in the mid-infrared band with a working wavelength of 9.2–10.8 μm. Their typical output power ranges from hundreds of watts to several kilowatts. They are widely used in industrial processing scenarios such as laser cutting, welding, marking and surface treatment, as well as infrared countermeasures, lidar and other fields.

In the above applications, diffraction gratings undertake key functions including wavelength tuning and spectral line selection, high-power beam combining, and output coupling control. Unlike gratings used in conventional UV-Vis spectrometers, gratings for high-power CO ₂ lasers must meet three core requirements simultaneously: high diffraction efficiency (>95%), high laser-induced damage threshold (> kW/cm² level), and low absorption loss.

At present, only a small number of professional grating manufacturers worldwide have mass production capacity for gratings applied in high-power CO ₂ lasers. Domestically, relevant institutions in Suzhou have fabricated metal substrate gratings with a maximum size of 300×300 mm, whose diffraction efficiency exceeds 95%, reaching the level of similar international products. This paper discusses the topic from four dimensions: grating type selection, key parameter analysis, fabrication processes and selection essentials.