Why are laser wavelengths in the near-infrared range often used in therapies?

Laser wavelengths in the near-infrared range are often chosen for therapies primarily because of their ability to penetrate deeper into tissues. This property is particularly valuable in medical applications, such as in photothermal therapy or soft tissue surgeries, where reaching deeper structures without causing significant damage to the skin and surface tissues is crucial.

The near-infrared spectrum generally ranges from about 700 nm to 1400 nm, and at these wavelengths, light can travel further into biological tissues due to lower absorption by water and hemoglobin compared to visible wavelengths. This allows for effective treatment of deeper tissues, promoting healing, reducing pain, and facilitating various therapeutic effects while minimizing adverse effects on the outer layers of the skin.

The other options do not directly address the primary advantages associated with the use of near-infrared wavelengths in therapeutic contexts. While visibility, harm to the skin, and reflection may be considerations in specific applications or contexts, the depth of tissue penetration remains the most significant reason for utilizing this part of the electromagnetic spectrum in therapeutic lasers.