Which type of laser operates in free running pulsed mode?

The Nd:YAG laser, or Neodymium-doped Yttrium Aluminum Garnet laser, is known for operating effectively in a free-running pulsed mode. In this mode, the laser generates short bursts of energy that occur over a series of pulses rather than emitting a continuous beam of light. This is particularly advantageous in several applications, including aesthetic treatments, surgical procedures, and material processing, where high peak power and controlled energy delivery are needed.

The free-running mode relies on the laser's ability to build up energy in the gain medium before releasing it rapidly, creating the pulse. Nd:YAG lasers are versatile and can be configured for both pulsed and continuous wave operation, but their pulsed operation is commonly recognized due to its wide range of applications.

Other laser types listed do not primarily operate in a free-running pulsed mode. For example, CO2 lasers are generally utilized for continuous wave operation, especially in cutting and engraving applications. Diode lasers can also work in pulsed mode but are frequently operated in continuous wave mode for efficiency in various uses. HeNe lasers are typically employed in continuous wave operation primarily for low-power applications like alignment and demonstration purposes.