  We use a Raman four-wave mixing process to read-out light from atomic
coherence which is continuously written. The light is continuously generated
after an effective delay, allowing the atomic coherence to evolve during the
process. Contrary to slow-light delay, which depends on the medium optical
depth, here the generation delay is determined solely by the intensive
properties of the system, approaching the atomic coherence lifetime at the weak
driving limit. The generated light is background free. We experimentally probe
these properties utilizing spatial diffusion as an 'internal clock' for the
atomic evolution time.
