This is a paid asset, but now you can download Laser Beam Tripwire Shader Free.
Detail this asset from Unity Store: Original Link
Laser Beam Tripwire Shader v1.0
This package contains a couple of versions of a shader for animated tripwire-style laser beams using line renderers. The shader uses a single texture lookup to draw a beam with a simple static gradient (read from the Red channel), animated dust (Green channel), and animated noise (Blue channel). A texture and a prefab are included.
The package includes a version that uses edge blending towards the end, and a version with hard edges. If you want to use the edge blending version in forward rendering mode, make sure you enable the depth texture on your camera.
The laser beam does not use PBR (as it’s unlit anyway) and works both in Unity 4 and Unity 5.
Both versions of the shader include an emission gain slider that makes them compatible with Sonic Ether’s Natural Bloom & Dirty Lens image effects, if you happen to use those – otherwise it can be safely ignored.