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一个完整的光纤通信系统包括三个组成部分。光源、光纤和光检测器件。在前两讲中已对光源和光纤作了介绍。本文中将着重就光检测器件的构造、工作原理及其应用作一说明。 目前采用的光检测器件可分两种型式。一种是PIN型的光电二极管(简称PIN),另一种是雪崩光电二极管,用它的英文缩写(Avalanche Photo Diode)APD表示。 根据二者不同的特性将应用于不同的场合。那么两者的共同点和区别又是什么呢?共同点二者都属于PN结光检测器,其区别在于PIN内部设有光电流的放大作用即放大系数小于1,而APD内部由于有雪崩效应光电流有放大作用即放大系数大于1一直到数百甚至上千倍。
A complete optical fiber communication system consists of three components. Light source, optical fiber and light detection device. In the first two lectures have been introduced on the light source and optical fiber. This article will focus on the structure of the photodetector, working principle and its application as a description. The current optical detection device can be divided into two types. One is a PIN-type photodiode (PIN for short), the other is an avalanche photodiode, with its abbreviation (Avalanche Photo Diode) APD said. According to the different characteristics of the two will be applied to different occasions. What are the commonalities and differences between the two? The two are common to the PN junction photodetectors. The difference between them is that the amplification factor of the PIN with photocurrent is less than 1, while the APD has an avalanche effect Photocurrent amplification effect that amplification factor greater than 1 up to hundreds or even thousands of times.