光时分复用(OTDM)系统中基于电吸收调制器(EAM)的短脉冲光源及解复用器的设计考虑

研究了电吸收调制器（ＥＡＭ） 的衰减随外加反向电压增加而指数增加的情形下，短脉冲光源的脉冲输出和解复用器的开关窗口对ＥＡＭ 的消光效率、反向ＤＣ 偏置电压以及正弦ＲＦ 驱动信号的幅度等参量的依赖关系－ 在基于ＥＡＭ 的短脉冲光源中，输出脉冲的消光比等于ＥＡＭ 消光效率η与正弦驱动电压峰峰值Ｖｐｐ 的乘积，输出光脉冲的消光比和脉宽均与ＥＡＭ 的反向偏置电压无关，但输出脉冲的峰值功率与η、Ｖｐｐ 和Ｖｂ 都有关系－ 在基于ＥＡＭ的解复用器中，为了使解复用器的开关窗口近似为矩形，可利用ＥＡＭ 的削波效应，使Ｖｐｐ／２＞ Ｖｂ－ 在ＥＡＭ 的消光效率η已知时，通过仔细设计反向ＤＣ 偏置电压Ｖｂ 和正弦驱动电压的峰峰值Ｖｐｐ ，达到ＯＴＤＭ 解复用器所需要的开关窗口形状、宽度和消光比－

DESIGN CONSIDERATION OF EAM-BASED SHORT PULSE LIGHT SOURCES AND DEMULTIPLEXERS IN OTDM SYSTEMS

In this paper,It is investigated how the o utput of a short pulse source and the switching window of a demultiplexer depend on the ex tinction efficiency of an electroabsorption (EAM),the reverse DC bias voltage,an d the amplitude of the sinusoidal RF drive signal when the attenuation of EAM in creases exponentially with the applied reverse voltage.In an EAM-based short pu lse light source,the extinction ratio and pulsewidth of the generated pulse are dependent on the product of the extinction efficiency η and the peak-to-peak value of the sinusoidal drive voltage Vpp, and independent on the DC bias of EAM Vb.However,the peak powe r of the generated pulse is related to η,Vpp and Vb.In an EAM-based demultiplexer,the clipping effect of EAM can be us ed to obtain an approximately rectangular switching window.When the extinction e fficiency of EAM η is given,the reverse DC bias voltage Vb and the peak-to-peak value of the sinusoidal drive voltag e Vpp must be designed elaborately to obtain appropriate w indow shape,width and extinction ratio required by an OTDM demultiplexer.