The future of optical communication

This paper will introduce the generation and characteristics of optical soliton, the structure, key technology and superiority of optical soliton communication system. At last, the development of optical soliton communication is also introduced.

The practical process of the keywords color astigmatism soliton

Everything is progressing in the development, optical communication in the ultra long distance, super large capacity development process, encountered the optical fiber loss and dispersion problem, limit its development space. Scientists and insiders were inspired by nature to discover special soliton wavelets, and the wave of optical fiber, amplitude and speed is the same as that of optical soliton. A new generation of optical fiber communication system using optical soliton to transmit information is a revolution in optical communication technology, which can achieve full optical communication without light and electricity conversion, and it is a great power in the long-distance and super capacity transmission.

1 Optical soliton Communication concepts

1.1 Resistance of conventional optical fiber communication forward development

We know that the loss and dispersion of optical fiber are the two main factors restricting the transmission distance and capacity of linear optical fiber communication systems, especially in high speed optical fiber communication systems above gbit/s, the dispersion will play a major role, that is, because the pulse broadening will reduce the system capacity and the distance of transmission is limited.

The dispersion of light refers to some phenomena that occur because of the relationship between the refractive index of the material and the wavelength of the light. For a certain matter, the refractive index n is a certain function of the wavelength person: n=f (λ) determines the refractive index n with the wavelength of the change in the speed of the amount, called the material dispersion.

The dispersion of the optical pulse is the dispersion of the optical fiber, which makes the light propagating at different wavelengths in the optical pulse inconsistent, resulting in the broadening of the light pulse.

1.2 How the light soliton is produced

1 people are inspired by the natural world

1834 Scott Russel to the ship in the river movement in the formation of water wave crest observation, found that when the ship suddenly stopped, the original in front of the boat was pushed up the wave still maintain the original shape, amplitude and speed forward movement, after a considerable period of time to disappear. This is the famous solitary wave phenomenon.

2 mechanism of optical soliton generation

Soliton and solitary wave, which is a special shape short pulse, is a special product of optical nonlinear effect.

In the case of weak light intensity, the refractive index of the optical fiber medium is constant, that is, N does not change with light intensity. However, under the strong light, the Kerr effect of the physical crystal optics shows that the refractive index of the optical fiber medium is no longer constant, and the refractive index increment δn (t) is proportional to the Yu Guangyang [E (t)]2. It is also known that the refractive index and the phase have a certain relationship, the phase and frequency have a relationship, then the light intensity will cause the change of the frequency of the light signal, so that the propagation speed of light changes.

The group velocity dispersion of optical fiber and the nonlinearity of optical fiber make the soliton stable in the fiber. When the working wavelength is greater than 1.3μm, the optical fiber exhibits a negative group velocity dispersion, i.e. the high frequency component propagating speed in the pulse and the low frequency component propagation speed is slow. Under the action of the strong input light field, the optical fiber will produce a strong nonlinear Kerr efficiency, namely the optical fiber's emissivity and the intensity of the light field directly proportional to the pulse phase proportional to the intensity of the optical field, that is, self-phase modulation, pulse after the edge than the pulse movement faster, resulting in pulse compression benefits. When the squeezing effect is balanced with the pulse broadening effect caused by the dispersion alone, a bound light pulse--optical soliton--can propagate far without changing the shape and velocity.

Solitary wave is a special form of wave, it has only a crest, the wavelength is infinite, in a long distance of transmission can maintain the waveform unchanged. The concept of soliton is derived from the phenomenon of solitary wave, and the system that transmits the information to communication on the soliton is called Optical soliton transmission system with the optical fiber as the transmission medium.