Method for compensating dispersion of fiber-optic transmission line

FIELD: fiber-optic transmissions, possible use for compensating dispersion of a fiber-optic transmission line.

SUBSTANCE: in accordance to the method, optical amplifiers are included into fiber-optic transmission line. Compression of optical impulses at receipt is achieved. Optical amplifiers with nonlinear transfer characteristic are used. At the output of optical amplifier an attenuator is coupled with linear transfer characteristic, output of which is connected to input of optical limiter of threshold from below. Duration of optical impulse at output is regulated.

EFFECT: expanded area of possible use.

6 dwg

 

The invention relates to fiber optic communication technology and can be used for dispersion compensation fiber-optic transmission lines.

The known method [1], namely, that in the regeneration section of fiber-optic transmission lines periodically with a certain interval includes optical amplifiers by adjusting the gain of which change the power of optical radiation into the optical fiber so as to provide the conditions in line solitons. However, the implementation of soliton and quasisolitons modes are errors on the acceptance due to the interaction of solitons.

A significant reduction of the error probability due to the interaction of solitons provides a known method [2], namely, that on the amplification plot of the optical fiber transmission line sequentially stacked two types of optical fibers at greater length fits the usual optical fiber transmission line, and at the far end of the amplifying section is a short length of special optical fiber (decreased dispersion fiber - DDF) with chromatic dispersion, exponentially decreasing in length. Adjusting the gain of an optical amplifier in the middle end of the amplification plot change the power of the optical radiation at the input of the special fiber, so that n is m is ensured by the compression of the pulse. The compression here is mostly determined by the properties and length of the special optical fiber and cannot be regulated within wide limits, which limits the scope of the method.

The essence of the invention is the expansion of the scope.

This entity is achieved by the fact that according to the method of dispersion compensation fiber-optic transmission lines, namely, that in the optical fiber transmission line include optical amplifiers, by adjusting the gain of which provide compression of optical pulses at the reception, while optical amplifiers with nonlinear transfer function at the output of the optical amplifier includes an attenuator with a linear transfer function, the output of which is connected to the input optical threshold limiter below, changing the gain of the optical amplifier, the attenuation of the attenuator and the threshold optical threshold limiter bottom, adjust the duration of the optical pulse at the output.

Figure 1 shows the block diagram of the device for implementing the inventive method; figure 2 presents the impulse at the output S of the transmission line; figure 3 and 4 shows the pulse at the output of the amplifier; figure 5 and 6 shows the pulse at the output of the limiter.

The device contains op is practical fiber 1 and the transmission line, in series with which is included the optical amplifier 2, an attenuator 3 and the optical threshold limiter 4.

The device operates as follows.

Served on the input of the optical amplifier 2 optical pulses from the optical fiber 1 and the transmission line and distort their shape. For example, when applying to the input of an optical amplifier with a quadratic characteristic of the Gaussian pulse shape (figure 2) at the output of the amplifier depending on the gain of the receive pulses are distorted form as in figure 3 or 4. Adjust the gain of an optical amplifier with a nonlinear transfer function and change the degree of distortion of the pulse shape (figure 3, figure 4). Change the attenuation of the attenuator 3, "cut" impulse from below using an optical threshold limiter 4 and thereby regulate the duration of the pulse at the output (figure 5, 6).

In the proposed method, unlike the prototype, the compression ratio of the pulse output is changed only by control of the gain of the optical amplifier and the attenuation of the attenuator that allows you to increase the limits of adjustment of the compression of optical pulses, thereby to expand the scope of application of the method.

LITERATURE

1. Uscular, Agrawal G.P. Optical solitons. From fibers to photonic crystals. - M.: Fizmatlit, 2005. - 648 S.

2. US 6407841 B1.

The method of dispersion compensation fiber-optic transmission lines, namely, that in the optical fiber transmission line include optical amplifiers, by adjusting the gain of which achieve compression of optical pulses at the reception, characterized in that the optical amplifiers with nonlinear transfer function at the output of the optical amplifier includes an attenuator with a linear transfer function, the output of which is connected to the input of the optical threshold of the limiter at the bottom, changing the gain of the optical amplifier, the attenuation of the attenuator and the threshold optical threshold limiter bottom, adjust the duration of the optical pulse at the output.



 

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