Molecular Lasers

Source: SciTechDaily

Molecular Gas Lasers: An Overview

Molecular gas lasers are a type of gas laser where the laser-active components are molecules rather than individual atoms or ions. These lasers utilize excited states of molecules, which can involve electronic excitation as well as vibrations and rotations of the molecules. As a result, molecular gas lasers emit long-wavelength laser light in the mid or far infrared spectral region.

Common Types of Molecular Gas Lasers

Some of the most common types of molecular gas lasers include:

• Carbon dioxide (CO₂) lasers
• Carbon monoxide (CO) lasers
• Nitrogen (N₂) lasers
• Hydrogen fluoride (HF) lasers
• Deuterium fluoride (DF) lasers
• Ammonia (NH₃) lasers
• Methanol (CH₃OH) lasers

These lasers can operate on various rotational-vibrational lines, enabling multi-line or single-line emission. Intracavity bandpass filters can be used for achieving single-frequency operation.

Pumping Methods for Molecular Gas Lasers

Molecular gas lasers can be pumped in several ways:

• Electrically pumped with a gas discharge or energetic electron beams
• Chemically pumped through exothermic reactions
• Optically pumped using another laser source

For instance, the CO₂ laser is commonly electrically pumped and can achieve high output powers with good efficiency. Chemical lasers, such as hydrogen fluoride (HF) and deuterium fluoride (DF) lasers, utilize chemical reactions for pumping and can deliver high output powers for military applications.

Optical pumping, although less common, involves using an external laser source to excite the laser-active molecules. This method has been employed in some molecular lasers for specific applications.

Conclusion

Molecular gas lasers offer a versatile platform for generating laser light in the infrared spectral region. With various pumping methods and a wide range of laser-active molecules, these lasers find applications in spectroscopy, military technologies, and other fields requiring high-power infrared lasers.

Source: Ars Technica
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