KR100450748B1 - Bi-directional optical transmitter with stimulated brillouin amplification and method thereof - Google Patents

Abstract

Disclosed are a bidirectional optical transmission apparatus and method using induced Brillouin amplification. The optical transmission device according to the present invention includes a first transmitter, an amplifier, a second transmitter, and a transmitter and an amplifier. The first transmitter generates a first optical signal having a predetermined frequency, the amplifier amplifies the first optical signal, the second transmitter generates a second optical signal having a predetermined frequency, and the transmission and amplification unit first The optical signal and the second optical signal are transmitted in opposite directions, and the second optical signal is induced Brillouin amplified by the first optical signal. By amplifying the second optical signal by the first optical signal using the induced Brillouin amplification phenomenon, the second optical signal can be transmitted without a separate amplifier for the second optical signal, and by changing the frequency of the first optical signal By selectively amplifying the second optical signal, a signal to be received can be selected for the second optical signal without a separate optical filter, thereby enabling bidirectional optical transmission having a simple structure and low cost.

Description

Bi-directional optical transmitter with stimulated brillouin amplification and method

The present invention relates to an optical transmission device, and more particularly, to a bidirectional optical transmission device and method using induced Brillouin amplification.

For bidirectional optical transmission, a method of amplifying and transmitting both optical signals in both directions is required. Conventionally, as an amplification method for bidirectional optical transmission, an amplification method using a specially designed amplifier, a method using a semiconductor laser amplifier, amplification using a WDM coupler, and the same direction of the bidirectional optical signal using a unidirectional method There is a method of amplifying with an amplifier.

The method of amplifying a bidirectional optical signal using a specially designed amplifier has a problem in that the structure is complicated and expensive because the optical filter and the device for controlling the same are used in duplicate.

The amplification method using a semiconductor laser amplifier is complicated in structure and expensive because the output of the semiconductor laser is small and the gain can be changed according to the power change between each channel of the WDM. There is this.

The method of amplifying a bidirectional optical signal using a WDM coupler and then amplifying it with a unidirectional amplifier has a signal amplification characteristic depending on the channel isolation characteristics of the WDM coupler. Receive. In addition, there is an expensive problem because both directions use an optical filter for channel selection.

The technical problem to be achieved by the present invention is to eliminate the need for amplifying means and optical filters in the opposite direction by using an amplifying means and an optical filter for only one optical signal in bidirectional optical transmission. It is to provide a bidirectional optical transmission device and method with a simple structure and low cost.

1 is a block diagram illustrating an embodiment of a bidirectional optical transmission device according to the present invention.

2 is a conceptual diagram illustrating an embodiment of a frequency relationship between a first optical signal and a second optical signal in the bidirectional optical transmission device according to the present invention.

According to an aspect of the present invention, there is provided a bidirectional optical transmission apparatus including: a first transmitter configured to generate a first optical signal having a predetermined frequency; An amplifier for amplifying the first optical signal; A second transmitter for generating a second optical signal having a predetermined frequency; And a transmission and amplifying unit which transmits the first optical signal and the second optical signal in opposite directions, and induces Brillouin amplification of the second optical signal by the first optical signal.

According to an aspect of the present invention, there is provided a bidirectional optical transmission method comprising: generating a first optical signal having a predetermined frequency; Amplifying the first optical signal; Generating a second optical signal having a predetermined frequency; And transmitting the first optical signal and the second optical signal in opposite directions, and amplifying the induced Brillouin amplification of the second optical signal by the first optical signal.

Hereinafter, a bidirectional optical transmission apparatus and method according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram illustrating an embodiment of a bidirectional optical transmission device according to the present invention. Referring to FIG. 1, the bidirectional optical transmission apparatus according to the present invention includes a first transmitter 100, an amplifier 120, a second transmitter 140, a transmitter and amplifier 160, and an optical filter 180. It is preferable to include. For convenience of description, in FIG. 1, a receiver 300 for receiving an optical signal generated by the first transmitter 100 and a receiver 320 for receiving an optical signal generated by the second transmitter 140 together. Shown.

The first transmitter 100 generates a first optical signal 10 having a predetermined frequency. Preferably, the first transmitter includes a frequency adjuster 105 that changes and stabilizes the frequency of the first optical signal. The first optical signal is transmitted in the first direction shown on the transmission and amplification unit 160.

The amplifier 120 amplifies the first optical signal generated by the first transmitter.

The second transmitter 140 generates a second optical signal 20 having a predetermined frequency. The second optical signal is transmitted in the second direction shown below the transmission and amplification unit 160.

The transmitting and amplifying unit 160 transmits the amplified first optical signal 11 and the second optical signal 20 in the first direction and the second direction, respectively, and simultaneously transmits the second optical signal by the first optical signal. Stimulated Brillouin amplification.

When the plurality of signals having different wavelengths are combined with the first optical signal 11, the optical filter 180 selects a signal having a desired wavelength from among them. In the Wavelength Division Multiplexing (WDM) scheme, a plurality of signals having different wavelengths are combined and transmitted to transmit a plurality of signals in a single line. However, for the second optical signal, as described below, induced Brillouin amplification is selectively generated to select a signal to be received from among the plurality of signals.

In order for induced Brillouin amplification to occur, the intensity of the first optical signal 11 must be greater than the induced Brillouin scattering threshold. In this case, the corresponding second optical signal 20 has an induced Brillouin gain. Therefore, the second optical signal 20 can be transmitted without a separate amplifier.

The induced Brillouin amplification by the first optical signal 11 is characterized in that the band is shifted to a long wavelength of about 10 GHz. That is, induced Brillouin amplification occurs only when the second optical signal 20 to be amplified has a frequency 10 GHz lower than the corresponding first optical signal 11. If the second optical signal 20 has a frequency other than 10 GHz lower than the corresponding first optical signal, the induced Brillouin amplification will not occur, and thus the signal cannot be received by the receiving device 320.

For example, if the frequencies of the signals included in the second optical signal are arranged at 100 GHz intervals such as 193.50 THz, 193.40 THz, 193.30 THz, and 193.20 THz, respectively, amplify and receive all signals included in the second optical signal. In order to do this, the frequencies of the signals included in the corresponding first optical signal should be 193.51 THz, 193.41 THz, 193.31 THz, and 193.21 THz, respectively, and if only the second signal having the frequency of 193.40 THz is to be received, the first optical If the frequencies of the signals included in the signal are 193.52 THz, 193.41 THz, 193.32 THz, and 193.22 THz, respectively, there will be a 20 GHz frequency difference for the first, third, and fourth signals, so that no induced Brillouin amplification will occur. . If the frequency of the first optical signal is lowered to be similar to that of the corresponding second optical signal, it may be affected by Rayleigh scattering.

Such frequency alignment and frequency stabilization can be easily implemented using commercially available wavelength lockers.

In addition, the frequency of the commonly used distributed feedback (DFB) laser shows a characteristic that the frequency decreases by about 10 GHz when the operating temperature increases by 1 degree Celsius, thereby changing the frequency by changing the operating temperature regardless of other operating characteristics. Can be.

2 is a conceptual diagram illustrating an embodiment of a frequency relationship between a first optical signal and a second optical signal in the bidirectional optical transmission device according to the present invention.

Referring to FIG. 2, the signals S1, S3, S5, and S7 included in the second optical signal have different frequencies f1, f3, f5, and f7, respectively, and different frequencies f2, f4, f6, respectively. And signals S2, S4, S6, and S8 included in the first optical signal having f8). The corresponding first and second optical signal pairs each have a frequency difference of 10 GHz. That is, the signals S1, S3, and S7 to be amplified and received among the second optical signals have frequencies of 10 GHz lower than the signals S2, S4, and S8 included in the corresponding first optical signals, respectively.

Referring to FIG. 2, S5 of the second optical signals is an unwanted signal and has a frequency 20 GHz lower than the corresponding first optical signal S6. In this case, since the induced Brillouin amplification does not occur, the signal S5 is not received by the receiving device 320.

Therefore, when the reception of each signal included in the second optical signal is desired and the reception is not desired, the frequency of the signal included in the corresponding first optical signal is changed, respectively, thereby selecting a desired signal without a separate optical filter. Can be.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the bidirectional optical transmission device and method according to the present invention, the second optical signal is amplified by the first optical signal by using the induced Brillouin amplification phenomenon, so that the second optical signal is not transmitted to the second optical signal without a separate amplifier. Can transmit

In addition, by selectively amplifying the second optical signal by changing the frequency of the first optical signal, it is possible to select a signal to be received for the second optical signal without a separate optical filter, so that the structure is simple and inexpensive bidirectional optical transmission This is possible.

Claims (12)

A first transmitter for generating a first optical signal including at least one signal arranged at a predetermined frequency interval; An amplifier for amplifying the first optical signal; A second transmitter for generating a second optical signal including at least one signal arranged at a predetermined frequency interval; The first optical signal and the second optical signal are transmitted in opposite directions, and the second optical signal is based on a frequency interval of signals included in the first optical signal and a frequency interval of signals included in the second optical signal. And a transmission and amplifying unit configured to selectively induce Brillouin amplification of signals included in the signal. The bidirectional optical transmission device of claim 1, wherein the amplifying unit makes the intensity of the amplified first optical signal larger than the induced Brillouin scattering threshold. The method of claim 1, And a frequency adjusting unit for arranging at least one or more signals included in the first optical signal at predetermined frequency intervals. The method of claim 1, And the first transmitter comprises a DFB laser whose frequency changes with a change in operating temperature to change the frequency of the first optical signal based on the operating temperature. 2. The bidirectional optical transmission device according to claim 1, wherein the first optical signal has a frequency of 10 GHz higher than the second optical signal. The method of claim 1, And an optical filter for selecting a signal having a desired wavelength from among signals arranged at predetermined frequency intervals included in the first optical signal. The method of claim 6, wherein the signal to be amplified among the signals included in the second optical signal has a frequency 10 GHz lower than a corresponding signal among the signals included in the first optical signal, And a signal not to be amplified among the included signals has a frequency other than 10 GHz lower than a corresponding signal among the signals included in the first optical signal. (a) generating a first optical signal comprising at least one signal arranged at a predetermined frequency interval; (b) amplifying the first optical signal; (c) generating a second optical signal comprising at least one signal arranged at a predetermined frequency interval; (d) transmitting the first optical signal and the second optical signal in opposite directions, and based on a frequency interval of the signals included in the first optical signal and a frequency interval of the signals included in the second optical signal. And selectively inducing Brillouin amplification of signals included in the second optical signal. 9. The method of claim 8, wherein step (b) causes the intensity of the amplified first optical signal to be greater than the induced Brillouin scattering threshold. 9. The method of claim 8, wherein the first optical signal has a frequency of 10 GHz higher than the second optical signal. The method of claim 8, and (e) selecting a signal having a desired wavelength from among signals arranged at predetermined frequency intervals included in the first optical signal. 12. The method of claim 11, wherein the signal to be amplified among the signals included in the second optical signal has a frequency 10 GHz lower than a corresponding signal among the signals included in the first optical signal, And a signal not to be amplified among the included signals has a frequency other than 10 GHz lower than a corresponding signal among the signals included in the first optical signal.