Go back to your modeling program. Make a series of concentric cylinders for the beam - you need at least 3 layers, more is better, probably 7 to 10 for high quality work. Attach a different material zone to each, so you can have different shaders on each.

Set up the color you want in Ambient_Color and set Ambient_Value to 1. You can have different colors on the inner versus the outer cylinders if you like.

Then set the innermost cylinder to be .2 transparent, all the remaining ones at .8 to .99 transparent - the right amount will depend on how many layers you make.

Here's my demo with 3 cylinders. The innermost is yellow - the others are green.

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