| The principle of all-optical frequency multiplication is that, the high-frequency signals is produced by the low-frequency optical signals modulated by the nonlinear effects of optoelectronic devices, the method has a significant advantage in price. This paper proposes two all-optical frequency multiplication technology solutions, the one is based on the terahertz optical asymmetric demultiplexer(TOAD) and signals separated with delay construction, and the other one is based on a feedback system with delay. TOADs are used in both schemes, so TOAD is analyzed, firstly. The work status of TOAD is simulated with mathematical model, the 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 of TOAD and the signals separated with delay construction, the all-optical frequency doubling, tripling and quadrupling are simulated, and the frequency doubling of the clock is implemented with simulations and experiments for200Mb/s and1Gb/s clocks. The second scheme is to use a feedback system with delay for all-optical frequency multiplication, this paper introduces the structure and key technologies of the system firstly, including:accurate delay controller, all-optical wavelength conversion and all-optical "or" logic. Accurate delay controller is achieved by using shiftable self-focusing lens, all-optical wavelength conversion and all-optical "or" logic are both achieved by TOAD. With the scheme of feedback system with delay, the all-optical frequency doubling, tripling and quadrupling of the clock is implemented with experiment for500Mb/s clock and frequency quadrupling and quintupling for250Mb/s clock. The experiments have good effects. If improving the performance of TOAD, the scheme has a great prospect to generate a high frequency signal. |
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