How Do Transverse Modes Shape Laser Beam Profiles?

[McKendrigo]

Hi,

I'm trying to get my head around the concept of transverse modes as seen from the outputs of lasers. I'm really struggling to even visualise the concept. From what I grasp, the transverse mode represents the intensity profile of the output laser beam. However I just can't make the jump from the basic picture of transverse oscillating perpendicular electric and magnetic fields to the picture of the intensity profiles for the transverse modes.

Or, put another way, I can easily visualise the variation of the electric and magnetic fields in a longitudinal (axial direction of the cavity) direction, but I can't visualise or understand why there would be a variation of these fields in a transverse direction.

Sorry for the horribly vague question, but any sort of help would be welcome...

Thanks

 

[Valerie Park]

!The concept of transverse mode is quite complex and it can be difficult to visualize. Essentially, a transverse mode is the pattern of the electric and magnetic fields at the output of a laser which defines the shape of the beam. This pattern is determined by the optical cavity of the laser, which determines the path the light takes and thus its shape. As the light passes through the cavity, it interacts with certain elements like mirrors and lenses which cause the beam to oscillate in the transverse direction, creating a pattern. This pattern is known as the transverse mode and it is usually represented as an intensity profile. To help you visualize the concept of transverse modes, you could think of it as a wave propagating through a medium. The wave has peaks and troughs, and these represent the intensity of the light at different points along the wave. In the case of a laser, the wave is the light inside the cavity and the intensity profile shows how the light will spread when it exits the cavity. Hopefully this explanation gives you a better understanding of the concept of transverse modes.