A scheme is proposed to achieve all-optical wavelength conversion and all-optical OR-logic gate, which are two key techniques for repetition rate multiplication of pseudorandom bit sequences (PRBS) based on terahertz optical asymmetric demultiplexer (TOAD). The switch characteristics of TOAD are discussed followed by 10 Gb/s wavelength conversion and all-optical OR-logic gate with theoretical simulations and experiments. The results indicate that the wavelength conversion and all-optical OR-logic gate can be implemented at ultra-high bit rate by this TOAD scheme if the widths of control pulse and switch window are smaller. Furthermore, all-optical PRBS with higher rate can be generated by employing both of the key techniques to achieve the repetition rate multiplication of PRBS.