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V_pp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、V_pp和V_b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V_pp/2>V_b.在EAM的消光效率η已知时,通过仔细设计反向DC偏置电压V_b和正弦驱动电压的峰峰值V_pp,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 output of a short pulse source and the switching window of a demultiplexer depend on the extinction efficiency of an electroabsorption(EAM),the reverse DC bias voltage,and the amplitude of the sinusoidal RF drive signal when the attenuation of EAM increases exponentially with the applied reverse voltage.In an EAM-based short pulse 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 V_pp,and independent on the DC bias of EAM V_b.However,the peak power of the generated pulse is related to η,V_pp and V_b.In an EAM-based demultiplexer,the clipping effect of EAM can be used to obtain an approximately rectangular switching window.When the extinction efficiency of EAM η is given,the reverse DC bias voltage V_b and the peak-to-peak value of the sinusoidal drive voltage V_pp must be designed elaborately to obtain appropriate window shape,width and extinction ratio required by an OTDM demultiplexer.