Here is a tutorial for a beam like this:
http://www.gfxvoid.com/tutorials/2/beam/final.jpg
First, create a blank canvas. I made mine 500 by 500.
Then zoom out once.
http://www.gfxvoid.com/tutorials/2/beam/01.jpg
Then, take a white brush(I used 250) and make a line starting form outside the canvas down outside the canvas, so there is a line covering the whole canvas.
http://www.gfxvoid.com/tutorials/2/beam/02.jpg
Then select the layer with the marquee tool. Be sure to select the whole thing. Now go Edit>Fill(Or Shift+F5). Pick whatever color you want(I used red, or #FF0000) and set the blending mode to Color. At this point, you can zoom out.
http://www.gfxvoid.com/tutorials/2/beam/03.jpg
Yes, I know that looks like crap. Go to Filter>Blur>Gaussian Blur and use 10, depending on what size yours is. It should look like this.
http://www.gfxvoid.com/tutorials/2/beam/04.jpg
Looking slightly better. Now double the layer(drag the layer into the New Layer icon) and make it about half as wide. Make the layer under invisible for now so the top one is easier to work with.
http://www.gfxvoid.com/tutorials/2/beam/05.jpg
Now go to Distort>Shear. Use these settings or something similar.
http://www.gfxvoid.com/tutorials/2/beam/06.jpg
Now duplicate the layer and move it up so that they look connected. Keep doing this until it covers the whole canvas. Then, merge all the layers. Mess around with the widths of the wavy part, the beam, or both to the point where the beam is completely inside the waves.
http://www.gfxvoid.com/tutorials/2/beam/07.jpg
Cut the wave layer on every other place where it crosses the beam. Then paste it right where it was. Merge and flatten the pasted parts into one layer. Then move the original wave layer under the beam. Now make the beam layer underneath thinner until there are no visible seams. Now just merge everything and flatten.
http://www.gfxvoid.com/tutorials/2/beam/08.jpg
EXTRA: Add a red and black background and it will look better.
http://www.gfxvoid.com/tutorials/2/beam/09.jpg
Yeah, I know. You can see the lines and whatnot, but it usually doesn't happen
EDIT: I just realized it looks pretty cool with bright blue.
Here
And with a bigger canvas.