Hayat Majeed M, Ramirez David A
Center for High Technology Materials and Electrical and Computer Engineering Department, University of New Mexico, Albuquerque, New Mexico 87106, USA.
Opt Express. 2012 Mar 26;20(7):8024-40. doi: 10.1364/OE.20.008024.
Novel theory is developed for the avalanche multiplication process in avalanche photodiodes (APDs) under time-varying reverse-biasing conditions. Integral equations are derived characterizing the statistics of the multiplication factor and the impulse-response function of APDs, as well as their breakdown probability, all under the assumption that the electric field driving the avalanche process is time varying and spatially nonuniform. Numerical calculations generated by the model predict that by using a bit-synchronous sinusoidal biasing scheme to operate the APD in an optical receiver, the pulse-integrated gain-bandwidth product can be improved by a factor of 5 compared to the same APD operating under the conventional static biasing. The bit-synchronized periodic modulation of the electric field in the multiplication region serves to (1) produce large avalanche multiplication factors with suppressed avalanche durations for photons arriving in the early phase of each optical pulse; and (2) generate low avalanche gains and very short avalanche durations for photons arriving in the latter part of each optical pulse. These two factors can work together to reduce intersymbol interference in optical receivers without sacrificing sensitivity.
针对雪崩光电二极管（APD）在时变反向偏置条件下的雪崩倍增过程，提出了一种新理论。推导了积分方程，用于描述倍增因子的统计特性、APD的脉冲响应函数及其击穿概率，所有这些都是在驱动雪崩过程的电场随时间变化且空间不均匀的假设下进行的。该模型生成的数值计算结果表明，在光接收机中使用比特同步正弦偏置方案来操作APD时，与在传统静态偏置下工作的相同APD相比，脉冲积分增益带宽积可提高5倍。倍增区域中电场的比特同步周期性调制有助于：（1）对于在每个光脉冲早期到达的光子，产生具有抑制雪崩持续时间的大雪崩倍增因子；（2）对于在每个光脉冲后期到达的光子，产生低雪崩增益和非常短的雪崩持续时间。这两个因素可以共同作用，在不牺牲灵敏度的情况下减少光接收机中的码间干扰。
