CN101383662A - All-optical burst amplifier based on SOA cross-gain modulation effect in optical network - Google Patents

Abstract

The invention provides a full gloss burst amplifier based on the SOA cross gain modulation effect, which comprises a laser, an optical combiner, an SOA, an EDFA and an optical filter, wherein a burst signal is input and a local continuous control signal is input to the SOA, the control signal is converted to the burst signal relatively complemented with the original input signal because of the SOA cross gain modulation effect, so the total power of the control signal and the burst signal is changed to be basically constant, the mixed signal is input to the EDFA for amplifying, and the transient effect of the EDFA can be greatly restrained, thereby the burst signal without anamorphic magnification can be obtained after the mixed signal is filtered by the optical filter. The invention can be applied to the amplification of the optical burst signal in the optical fibre network and the restraining of the transient effect of the EDFA.

Description

All-optical burst amplifier based on SOA cross-gain modulation effect in optical network

technical field

The invention belongs to the field of optical fiber technology, and relates to an all-optical burst amplifier, in particular to an all-optical burst amplification method and structure based on the SOA cross gain modulation effect in an optical network.

Background technique

Burst optical network is considered to be a promising technology in next generation all-optical network. In burst optical networks, data packets are framed into large burst packets for all-optical transmission on WDM channels. Optical amplifiers such as EDFA are used to compensate the optical fiber transmission loss in the network. However, traditional fiber amplifiers used in burst optical networks tend to exhibit transient response due to the dynamic characteristics of their own gain, that is, due to the long idle inter-packet interval in the burst signal, the EDFA transient effect will cause the burst packet Different parts of the circuit experience different gains, resulting in significant changes in output power, resulting in signal distortion and increased bit error rates. Therefore, suppressing the transient effect in optical burst amplification is a crucial technology in burst optical networks.

At present, some schemes have been proposed to suppress the transient effect of EDFA when amplifying burst signals. For example: the basic structure 1 in the prior art is shown in Figure 1, the input burst signal 101 and the continuous optical control signal 102 are coupled into the EDFA 104 through the coupler 103, and the EDFA is saturated by the control signal, thereby suppressing to a certain extent EDFA transient effects. Finally, the control signal is filtered by the optical filter 105 to obtain the amplified burst signal.

In the prior art shown in FIG. 1 , injecting the control light does not reduce the variation of the input power of the EDFA, and the transient effect cannot be well suppressed. In order to have better EDFA transient effect suppression results, it is necessary to inject a strong control light to saturate the EDFA. This technology has a high cost in practical applications, and also results in a small gain for burst signals.

The basic structure 2 in the prior art is shown in FIG. 2 , a part of the input signal 201 enters the feedforward control circuit 203 and the feedback control loop 204 through the input power monitoring 202 . A part of the output signal 208 amplified by the gain medium 206 enters the feedback control loop 204 through the output power monitoring 207 . Both the outputs of the feedforward circuit 203 and the feedback loop 204 enter the pumping source 205 . This technology changes the output of the pump source by monitoring changes in input and output power, thereby adjusting the gain of the amplifier. It is an optical amplifier with an automatic gain control circuit.

The prior art shown in Figure 2 requires complex feedforward and feedback circuits rather than all-optical processing and amplification. At the same time, due to the adoption of feedback technology, there is a lag in signal processing, which brings about the problem that the response time is not fast enough.

Contents of the invention

In view of the above-mentioned problems in the prior art, the present invention provides an all-optical burst amplifier based on SOA cross-gain modulation effect in a burst optical network, including a laser, an optical combiner, an SOA, an EDFA and an optical filter.

The laser, the optical combiner and the SOA constitute the transient suppression part of the amplifier, and the EDFA and the optical filter constitute the main amplification part.

Fig. 3 is a schematic diagram of the principle of the all-optical burst amplifier. The input burst signal 301 and a continuous optical control signal 302 with different wavelengths are combined and injected into the SOA 303 at the same time. When the input signal strength is sufficient to saturate the SOA, a cross-gain modulation effect occurs between the burst signal and the control signal. At this time, the gain obtained by the control signal is weak when the burst packet exists, and the gain obtained by the control signal becomes strong when the burst packet does not exist. Due to the fast gain response of the SOA, the control signal is quickly converted into a burst signal complementary to the original input signal. Therefore, the total power of the combined signal after the SOA has become substantially constant regardless of the presence or absence of burst packets. The combined signal with almost no power variation is injected into the EDFA 304 for amplification, the signal gain fluctuation is reduced, and the transient effect of the EDFA is also significantly suppressed. Finally, the control signal is filtered out with an optical filter to obtain an amplified output burst signal 305 without distortion.

Description of drawings

Fig. 1 is the technical structure 1 of EDFA transient suppression and optical burst amplification in the prior art;

Fig. 2 is the technical structure 2 of EDFA transient suppression and optical burst amplification in the prior art;

Fig. 3 is a schematic diagram of the principle of the present invention;

Fig. 4 is the structural representation of the all-optical burst amplifier of the implementation example of the present invention;

Fig. 5 is the experimental test result diagram of the implementation example of the present invention;

Detailed ways

The invention provides an all-optical burst amplifier based on SOA cross gain modulation effect in a burst optical network. The present invention will be described in detail below in conjunction with the accompanying drawings.

Implementation example

The present invention provides an all-optical burst amplifier based on the SOA cross-gain modulation effect in a burst optical network, as shown in Figure 4, the system includes an optical burst input signal 401, a DFB laser 402, a 3-dB coupler 403, SOA404, EDFA405 and optical filter 406; wherein, the input burst signal and the continuous optical control signal generated by the local laser are input into the SOA at the same time, and due to the SOA cross-gain modulation effect, the control signal is converted into a burst signal complementary to the original input signal Signaling, so the total power of the two becomes basically constant, and the combined signal is input into the EDFA for amplification, which can greatly suppress the transient effect of the EDFA, so that a burst signal without distortion can be obtained after passing through the filter.

In this embodiment, the optical burst signal 401 is a periodic burst optical signal with a wavelength of 1565 nm, a duty cycle of 50%, and a random binary sequence code of 2.5 Gb/s. Packet lengths range from 50µs to 200µs. The local laser 402 generates continuous light with a wavelength of 1562 nm as a control signal.

The SOA404 adopts the model of Alphion SALH 04P456, and the center wavelength is 1565nm.

The center wavelength of the optical filter 406 is 1565nm.

In this embodiment, the average powers of the optical burst signal and control light entering the SOA are -4.6dBm and -8.3dBm respectively. The bias current of SOA is set to 85mA, at this moment SOA is saturated, and its gain is 0.9dB. EDFA gain is 12dB. The total gain of the entire burst amplifier is about 13dB. Figure 5 shows the experimental results measured when the burst packet length is 100μs. Among them, 501 is the time-domain waveform (10mV/div) of the input optical burst signal; 502 is the burst signal waveform (100mv/div) amplified by the EDFA when the transient suppression technology is not used. At this time, the signal distortion is very serious, and the burst packet The gains experienced in different places are different, so the output power varies a lot, and its power intensity fluctuates up to 7.7dB; 503 is the burst signal waveform (100mv/div) amplified by the burst amplifier of the present invention, as can be seen, The transient effect of EDFA has been well suppressed, and the power intensity fluctuation of the output burst signal is only 1.2dB without distortion.

In this embodiment, the length of the burst packet basically has no effect on the amplification result. When the length of the burst packet is changed from 50 μs to 200 μs, the fluctuation of the output signal power intensity is kept below 1.5 dB.

In this embodiment, the input signal strength needs to saturate the SOA to generate the cross-gain modulation effect. Therefore, for input signals of different strengths, it is necessary to adjust the saturation condition of the SOA, which can be realized by changing the bias current of the SOA. Therefore, the amplifier can be used in different occasions such as power amplifier, line amplifier and preamplifier.

In this embodiment, when the optical power of the control signal is about 4 dBm lower than the average power of the input burst signal, the transient suppression effect is the most obvious and the amplification effect of the amplifier is the best. Because the complementary burst signal strength generated at this time is basically the same as the original burst signal strength after SOA, the total power of the combined signal is the most stable, the power fluctuation is the smallest, and the transient suppression effect is the best. If the optical power of the control signal is too large, the S0A gain obtained by the original burst signal will be too small, thereby reducing the power of the final output signal; on the contrary, if the optical power of the control signal is too small, the intensity of the generated complementary light will be insufficient, and the combined signal power will be reduced. The fluctuations are still high, and the transient suppression will be poor.

The above-mentioned embodiments are only used to illustrate the present invention, but not to limit the present invention.

Claims (6)

1. An all-optical burst amplifier based on SOA cross-gain modulation effect in an optical network, including all-optical devices such as laser, optical combiner, SOA, EDFA and optical filter. It is characterized in that the input burst signal and a local continuous optical control signal are input into the SOA at the same time. Due to the SOA cross-gain modulation effect, the control signal is converted into a burst signal complementary to the original input signal, so the total power of the two It becomes basically constant, and the combined signal is input into EDFA for amplification, which can greatly suppress the transient effect of EDFA, so that a burst signal without distortion amplification can be obtained after passing through the optical filter. 2. All-optical burst amplifier according to claim 1, it is characterized in that, input burst signal and continuous light control signal enter SOA simultaneously, utilize the cross-gain modulation effect in the SOA, control signal obtains when burst packet exists The gain of the control signal is very weak, and when the burst packet does not exist, the gain of the control signal becomes stronger, so the control signal is converted into a burst signal complementary to the original input signal, and the combined signal power of this signal and the original input signal becomes is basically constant. 3. the all-optical burst amplifier as claimed in claim 1 or 2, the combined signal input EDFA with constant power is amplified, and the signal gain fluctuation has just been reduced, thereby the transient effect that can occur in the traditional EDFA amplifier is also reduced. Significant suppression is obtained, and the input burst signal can be amplified without distortion. 4. The all-optical burst amplifier as claimed in claim 1 or 2, characterized in that by pre-SOA in EDFA, the cross-gain modulation effect of SOA is used to generate complementary burst signals to suppress EDFA transient effects. 5. The all-optical burst amplifier according to claim 1 or 2, characterized in that the best EDFA transient suppression result can be obtained by adjusting the relationship between the input burst signal and the power of the control signal. 6. The all-optical burst amplifier according to claim 1 or 2, characterized in that for different input signal powers, the EDFA transient effect can be significantly suppressed by adjusting the SOA saturation gain condition, so the amplifier can be used for power amplifiers, line Play and pre-play and other different occasions.

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