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调制方式为了传送信息,需要按照信息信号的变化对载波进行调制,所谓调制,就是改变载波的某种性质。因此,经调制后的载波就“装载”着所要传送的信息信号。光通信中使用的载波是光波,称为光载波。要实现光通信,就需要对光载波的某种性质进行调制。光波的性质包括它的强度,振幅,相位,频率,偏振态,传播方向等等。因此,对光波的调制相应地有强度调制(IM),振幅调制(AM),相位调制(PM),频率调制(FM),偏振调制(PL)等。改变光的传播方向,如声光调制,实际上是改变了原
Modulation In order to transmit information, it is necessary to modulate the carrier according to the change of the information signal. The so-called modulation means to change some properties of the carrier. Therefore, the modulated carrier “loads” the information signal to be transmitted. The carrier used in optical communication is light wave, which is called optical carrier. To achieve optical communications, it is necessary to modulate certain properties of optical carriers. The nature of the light wave includes its intensity, amplitude, phase, frequency, polarization, propagation direction and so on. Therefore, there are intensity modulation (IM), amplitude modulation (AM), phase modulation (PM), frequency modulation (FM), polarization modulation (PL) and the like corresponding to modulation of light waves. Change the light propagation direction, such as acousto-optic modulation, is actually changed the original