The generation of random numbers is an enduring research topic because of its scientific significance and wide applications. In the field of scientific computation, random numbers have been commonly used for Monte Carlo simulation, statistical sampling, and artificial neural networks. In engineering practice, random numbers can be used as ranging signals in radars, detecting signals in optical time-domain reflectometers, controlling signals in remote control and telemetry systems, scrambling and descrambling signals in digital communications, address or spreading codes in code division multiple access systems. In addition, random numbers are also often used to test the performance of optical communication devices and the quality of communication systems.