Статьи 6 семестр / Работы / The scheme for all-aptical networks

The scheme for all-optical networks

Optical communication technologies are employed in a wide variety of communication environments such as telecommunications, networking, data communications, industrial communication links, medical communications links, etc. Fiber optic networks are becoming increasingly commonplace in telecommunications applications due to their increased bandwidth and distance capabilities relative to copper networks. Optical fiber is the workhorse of the typical optical communication system, and the low loss, light weight, small size, flexibility and high intrinsic bandwidth of optical fiber help make optical communication systems more desirable than competing systems for the communication of both of digital and analog signals.

Modern fiber optic transmission devices, also called optical-electronic devices or optoelectronic devices, are coupled with optical fibers for data and signal transmission by converting optical signals into electrical signals, electrical signals into optical signals, or both. Fiber optic communication utilizes optical transmitters, optical receivers and optical fiber, among other components, to transmit light signals through the fiber. Traditional switches that connect optical fiber lines are electro-optic. They convert photons from the input side to electrons internally in order to do the switching and then convert back to photons on the output side.

The first thing in optical network circuit is the transmitter. It produces the signals that will travel through the cable. The optical regenerator is needed when the light signal is weakened by traveling over a long distance and needs a re-boost or strengthening. Actually, the light signal is copied and a new one with the same characteristics is sent by the regenerator. Finally, there is the optical receiver. It receives the light signals and encodes them into a readable form for the device at the end.

An all-optical fiber-optic switching device that maintains the signal as light from input to output. This method increases transmission speed manyfold. But it also requires the amplifier. Fiber optic cables without optical regenerators can be up to about one kilometer in length. With regenerators, they can go on almost forever.

Unfortunately, amplifying a signal adds noise. After a few amplifications, we need to regenerate the signal: we need a device that receives a noisy signal and emits a crisp clean signal. Currently the only way to build regenerators is to build an OEO (optical-electronic-optical) device: the inbound signal is translated from the optical domain into a digitized sample; the electronic component removes the noise from the digitized sample and then uses the cleaned-up digitized sample to drive a laser that emits a clean signal in the optical domain. OEO regenerators work just fine, but they slow us down by forcing us to work at the speed of electronics. This becomes the main challenge for engineers to make fiber optics desirable efficient.