  We present a high speed random number generation scheme based on measuring
the quantum phase noise of a single mode diode laser operating at a low
intensity level near the lasing threshold. A delayed self-heterodyning system
has been developed to measure the random phase fluctuation.By actively
stabilizing the phase of the fiber interferometer, a random number generation
rate of 500Mbit/s has been demonstrated and the generated random numbers have
passed all the DIEHARD tests.
