Terahertz optical asymmetric de- multiplexer (TOAD) is one of the key devices for all- optical signal processing with its fast response, good integration and stability. A scheme for all optical frequency multiplication is proposed based on the TOAD. The switch characteristics of the TOAD are discussed with simulations for bimodal output on the leading and tailing edges of the clock pulse as control, in addition with the dependence on some factors of the TOAD, such as energy of control pulse, window of TOAD, carrier recovery time. Based on the bimodal output effects, the all- optical frequency doubling, tripling and quadrupling are simulated, and the frequency doubling of the clock is implemented with simulations and experiments for 200 Mb/s and 1 Gb/s clocks.