Hello everyone！
Today I will discuss the optical signal and fiber.
Optical fiber communication uses laser light with a wavelength range in the near-infrared region of the spectrum. Optical fiber communication uses the principle of total reflection of light to transmit optical signals.
Many people think that the optical network only has optical signals. This is wrong. Optical networks serve other upper-layer networks. So we separate from the UNI (user side) and NNI (network side) side. The client-side, as its name implies, is On the side of the client-side signal, we know that the previous GSM-R base stations mainly output E1 signals, that is, 2M signals, so the optical network can provide E1 electrical ports; of course, optical networks can also access E3 electrical signals, GE The electrical signals and the optical signals of the 10GE interface, so the NNI side can provide a variety of optical interfaces. Looking at the NNI side again, this is the interface where the optical network equipment itself interconnects. It mainly consists of STM-64, OCH4, and other optical ports, so the NNI site is all-optical signals.
Optical networks are connected by optical cables. The types of optical cables commonly used today are mainly G.652 and G.654. The main difference between the two types of optical cables is that the attenuation and dispersion values of the optical signals in the unit are different. In the current network, G.652 is mainly used for SDH and microwave, and G.655 is mainly used for WDM.
