As others said you can use a parabolic reflector to direct the light in one direction.

I think this can work:

On one side place a parabolic reflector to direct the light in one direction.

On the other side place a circular reflector to direct the light back to the source. And place a tiny hole in this half circle to let the light out.

Quick drawing: http://zenphoton.com/#AAQAAkACAAEgWwAzALEBEwC0AO4A/wAAtADxAL...