Medical applications are a surgical fit for 2 µm lasers

Lasers have become essential for a wide range of industries, including medical applications. For many use cases, laser-based surgery improves accuracy compared to that of a scalpel, reduces the chance of infection, and creates clean cuts from a variety of angles. While laser sources with output wavelengths from 1 to 1.5 µm are widely available and often used, significant advancements in 2 µm lasers have led to their rapidly increasing popularity.

Evolution of 2 µm lasers

The first 2 µm laser sources were large and expensive liquid-nitrogen-cooled devices. Today, 2 µm diode lasers can be as small as 30 mm long, with even smaller 2 µm fiber lasers available. Both pulsed and continuous-wave (CW) emission are achievable.

The two rare-earth elements most used as laser gain dopants for both CW and pulsed laser operation are thulium (Tm³⁺) and holmium (Ho³⁺). Ions from these elements are used to achieve laser emission in many different host crystals and glass fiber types. Thulium lasers prove to be a better option for CW operation, while holmium better aligns with pulsed and Q-switched lasers because of the higher gain of holmium-doped crystals. Another advantage of thulium lasers is that their ions can be excited using commercially available laser diodes with wavelengths of 800 nm. Holmium requires a 1.9 µm pump source to excite the ions.

Laser sources in the 2 µm spectral region have proven very useful in medicine applications. Their high absorption in biological tissue, small thermal injury zone, and eye-safe wavelengths will likely continue boosting their popularity and become more widely used for laser surgery.