Which gas is typically used when the active medium is sealed in an airtight chamber for laser operation?

The choice of carbon dioxide (CO2) gas as the active medium in lasers that function within an airtight chamber is particularly due to its properties and operational efficiency. CO2 lasers work by having carbon dioxide molecules energized to create a population inversion, allowing for photon emission upon returning to lower energy states.

This gas has several advantages: it emits light at a wavelength of 10.6 micrometers, which is highly effective for applications such as cutting and welding materials, efficiency in conversion from electrical energy to laser light, and the ability to produce high power output. When contained in a sealed system, CO2 can help maintain the necessary pressure and density for optimal lasing conditions, ensuring consistent performance and preventing the contamination that might occur if an external atmosphere were present.

While helium, neon, and argon gases also play important roles in various laser types, they do not serve the same purpose in sealed CO2 laser applications; each of these gases typically has different operating mechanisms and applications, such as for lower-power laser systems or specific laboratory setups. Maintaining the integrity of the gas composition in a sealed environment is critical for achieving the desired lasing effect, making CO2 the preferred choice in this specific context.