Multimode Laser Beam Profile

The figure below shows the intensity profile of a monochromatic beam from a numerical simulation where the power is well spread over all guided modes.

Multimode laser beam profile.

Initial profile input angle 0. Here we investigated the effect of changing the input angle of a focused laser beam into a multimode fiber patch cable. A comparison of gaussian and multimode beams with equal energy was carried out in order to estimate influence of beam profile only. B 3d beam intensity profiles of the multimode dpss laser at the constructed far field using a converging lens.

Multimode fibers are used for the transport of light from a laser source to the place where it is needed particularly when the light source has a poor beam quality and or the high optical power requires a large area of the fiber core. Single mode lasing gaussian beam results in better reproducibility of analytical signals compared to multimode lasing while laser energy reproducibility was the same for both cases. The maximum beam spot size is 3 4 mm at z 0 and at 50 cm away from the laser it becomes 5 8 mm. Modifying beam profiles with multimode fibers by increasing the launch angle of a gaussian beam into a multimode fiber the output beam profile can be modified.

Focusing the light normal to the fiber face produced a near gaussian output beam profile figure 1 and increasing the angle resulted in top hat figure 2 and donut shaped figure 3 beam profiles.