Issues of a Laser Beam: Depolarization, Beam Quality Degradation and It´s Transmission System

High power laser has been used widely in industrial and surgical fields for its many advantages. However, the characteristics of the laser beam may evolve when it is transmitted from the laser exit to the application position through a medium, especially through optical fibers. The evolution of polarization and beam quality of the laser beam in large core fiber are investigated theoretically and experimentally. Investigations demonstrate the laser beam suffers depolarization and beam quality degradation when it propagates in optical fiber. The polarization degree (V) of the laser beam shows an exponential function of fiber length. The beam quality factor (M2) of the laser beam shows a composite tanh function of fiber length. The polarization degree decreases and beam quality degrades when the transmission distance in fiber increases. In addition, an optical fiber delivery system for high power laser beam is proposed concerning of the factors such as focusing lens and delivery fiber.