How does changing the fiber from 400 micron to 300 micron in a 940 diode laser for LAPT affect power density?

When the fiber diameter is changed from 400 microns to 300 microns in a laser application, such as in a 940 nm diode laser used for Low-Level Laser Therapy (LAPT), the power density increases. This occurs due to the relationship between the area through which the laser light is delivered and the total power output of the laser.

Power density is defined as the amount of power per unit area. When the diameter of the fiber is reduced while maintaining the same output power from the laser, the area through which the laser light is emitted becomes smaller. Since power density is inversely proportional to the area, a smaller area results in a higher power density.

This is significant because higher power densities can lead to more effective therapeutic outcomes in certain laser treatments, as they may enhance the effects of the laser on the tissues being treated. Hence, changing the fiber size in this manner directly influences the efficiency of the laser therapy.