提出利用开关窗口连续可调的太赫兹非对称解复用器(TOAD)实现对归零(RZ)码占空比的调节，分析了半导体光放大器(SOA)载流子恢复时间对伴随窗口的影响。实验上对2.5 Gb/s的RZ码占空比进行调节，实现了由50%（200 ps）压缩到25%（100 ps）和10%（40 ps），以及由25%展宽到50%。进一步研究结果表示，该结构对占空比展宽有上限，但对占空比的压缩上限远远不止实验中的40 ps，如果继续减小开关窗口宽度，利用该结构可以获得更小占空比RZ脉冲信号，实现皮秒甚至亚皮秒窄脉冲。

The method of using the continuously adjustable terahertz optical asymmetrical demultiplexer (TOAD) structure to tailor the duty ratio of return to zero (RZ) code is proposed. And the dependence of the additional window on the recovery time of semiconductor optical amplifier (SOA) in the TOAD loop is analyzed. For 2.5 Gb/s RZ code, experiments are demonstrated to compress the duty ratio from 50% (200 ps) to 25% (100 ps) and then 10% (40 ps), and broaden from 25% to 50%. The experiments indicate that with the TOAD structure, the duty ratio can be broadened up to 100% (RZ to NRZ), and can be narrow to picosecond or even sub-picosecond, if the switch window of the TOAD is tuned narrower.