Not really… Any emissive surface (without any tricks) will emit light in every direction!
The simplest trick is to use the incoming ray vector in the emission material, to calculate the desired amount of light in a specific direction that the material should give. Cycles, however, is not optimized for this kind of setups, and an huge amount of rays will just be lost by hitting a light that might not output any illumination. This requires more samples to keep a noise free render.
Three emissive planes… note that the two on the right don’t throw any light in the camera direction (amongst other directions), and that’s why they appear black.