JP2016009897A - Light amplifier and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light amplifier and a control method for the same that can control the level of an output signal so that the level of the output signal is equal to a target value when a burst signal input in a wavelength range assumed by a system is amplified by SOA.SOLUTION: A light amplifier has a function of detecting the wavelength and light intensity of an input optical burst signal and performing feed-forward control by referring to a table describing the relationship of input light intensity, output light intensity and driving current of SOA every wavelength. Furthermore, the light amplifier may perform control by only a function of detecting the light intensity of an output optical burst signal, and performing feed-back control.

Description

  The present invention relates to an optical amplifying device including a semiconductor optical amplifier and a control method thereof.

  In an optical subscriber network, a PON (Passive Optical Network) system is widely adopted. In IEEE, standardization of 10G-EPON which is a next generation system as well as G-EPON (Gigabit Ethernet (registered trademark) PON) which has already been commercialized has been completed. In ITU-T, standardization of XG-PON, which is a next-generation system, has been finished as well as B-PON (Broadband PON) and G-PON (Gigabit-capable PON) that have already been commercialized.

  These PONs have a network configuration in which a receiving station and a plurality of subscribers are coupled by a single optical fiber via an optical splitter disposed outside the station. The upstream signal and the downstream signal are the same depending on different wavelengths. It is transmitted in both directions on the optical fiber. The downlink signal is a continuous signal in which a signal for each subscriber is multiplexed using time division multiplexing (TDM) technology, and a transmission / reception device (ONU: Optical Network Unit) arranged in the subscriber is: From the continuous signal branched in the optical splitter, the signal of the time slot required for itself is taken out. The upstream signal is a burst signal that is intermittently transmitted from the ONU, is combined by an optical splitter to become a TDM signal, and is sent to the accommodation station. In this system, the optical fiber from the accommodation station to the optical splitter and the transmission / reception device (OLT: Optical Line Terminal) arranged in the accommodation station can be shared by a plurality of subscribers. Can be provided economically.

GE-PON, B-PON, and G-PON are commercial systems, but an increase in transmission path loss allowed in the system is one of the problems. If this can be realized, the number of subscribers to be accommodated can be increased by increasing the number of branches of the optical splitter, or the accommodation area can be expanded by extending the transmission distance to improve the accommodation efficiency numerically or planarly. I can expect. In order to solve this, a technique for compensating for the loss of a multi-branch splitter or a lengthened transmission path using an optical amplifying apparatus has been proposed. FIG. 1 shows the configuration of a PON system using an optical amplifier. As shown in the figure, the optical amplifying device is arranged as a repeater on an optical fiber that couples an optical splitter and a transmitting / receiving device (OLT) arranged in the accommodation station. As shown in FIG. 1, the optical amplifying device uses a bidirectional optical signal (wavelength λ _up ) and a downstream signal (wavelength λ _down ) bidirectionally using two optical multiplexers / demultiplexers. It is the structure to amplify. As an optical amplifier to be used, an optical fiber amplifier to which rare earth is added, a concentrated amplification type optical fiber Raman amplifier, a semiconductor optical amplifier (SOA) or the like can be used. In particular, the SOA has advantages over other optical amplifiers in terms of downsizing, economy, and power saving, and is a highly expected optical device in an optical subscriber network with strict cost requirements.

  One of the major problems in a PON system using an optical amplifier is the realization of an optical amplifier that amplifies an upstream signal. The uplink signal varies in intensity of the burst signal input to the optical amplifying device due to a difference in distance from the subscriber to the optical splitter, an individual difference in transmitter output in the ONU, and the like. The problem here is a burst signal having a high light intensity rather than a burst signal having a low light intensity. When a strong burst signal is input to the optical amplifying device, the output of the optical amplifying device increases accordingly, and when the transmission distance after optical amplification is not so long, an upstream signal exceeding the upper limit of the receiving sensitivity is received at the receiver in the OLT. There is a problem that a signal cannot be received after being input. When SOA is used as an optical amplifier, the SOA response time in the amplification process is about the same as the bit length of a giga-class signal, so when the light intensity of the input burst signal is large and amplified in the saturation region. There is a problem in that signal waveform deterioration called a pattern effect occurs due to excessive optical amplification at the rise of each bit. In other words, in order to apply the SOA-based optical amplifying apparatus to the PON, “(a) The transmission distance after optical amplification is constant regardless of the input light intensity”, “(b) It is required to expand the input dynamic range in two meanings of “reducing the influence of the SOA pattern effect on the strong signal input”.

  The above (a) can be solved by controlling the light intensity at the output of the optical amplifier to a constant value. Although the purpose is different, in order to relax the requirement for the input dynamic range of the burst receiver, there has been proposed a feedforward control optical amplifying device capable of controlling the output value to be constant (for example, Patent Document 1 and Non-Patent Document 1). Patent Document 1). FIG. 2 shows a basic configuration according to Non-Patent Document 1. The present optical amplifying apparatus includes a branching device, a photoelectric converter, a control circuit, a driving circuit, and an SOA. The branching device branches a part of the input burst optical signal. The photoelectric converter converts the branched burst optical signal into an electrical signal. The control circuit stores a relational expression calculated based on input light intensity and output light intensity (or gain) data with respect to the SOA drive current change acquired in advance, and the SOA calculates the input light intensity read from the electrical signal. The drive current at which the light intensity output from is the target value is calculated. The drive circuit sends out the calculated drive signal current. The SOA is driven by a drive signal current, and the gain is adjusted according to the light intensity of the input burst signal. Although not shown, in order to match the timing at which the optical signal whose input light intensity is detected is input to the SOA and the timing at which the SOA is driven by the drive signal current, as described in Patent Document 1, it is necessary. Accordingly, a delay line is arranged between the branching device and the SOA. As described above, with the configuration using the feedforward control method, the intensity of the input burst optical signal can be controlled to be a constant target value at the output. In Patent Document 1, an optical amplifying device having an optical amplifying function and an optical attenuator for adjusting the light intensity are separated. In the present structure based on Non-Patent Document 1, both functions are combined into a single SOA. Therefore, the number of optical components to be used can be reduced.

  In addition, when a strong burst signal is input, the current for driving the SOA is reduced, so that the SOA is less likely to be saturated as compared with the case where the driving current is fixed, and the influence of the pattern effect is reduced. In meaning, the input dynamic range is expanded.

Japanese Patent Application No. 2009-97446

N. Cheng, S.M. -H. Yen, J .; Cho, Z. Xu, T .; Yang, Y. et al. Tang, and L.L. G. Kazovsky, “Long Reach Passive Optical Networks with Adaptive Power Powering Usage Semiconductor Amplifiers,” ACP'2009, 200, FCP.2009.

However, SOA has a large wavelength dependency of amplification characteristics. Specifically, since there is a band filling effect in which the peak wavelength of amplification shifts to the short wave side as the drive current increases, the relationship between the input light intensity and the output light intensity (or gain) with respect to the drive current change varies depending on the wavelength. Consider a case where the output light level is set to a target value on the long wavelength side, and burst signals of _two different wavelengths (λ ₁ <λ ₂ ) are individually input as shown in FIG. At burst signal input wavelength lambda _2, the output light level of the target is obtained as a matter of course. On the other hand, with a burst signal input of wavelength λ _1, a sufficient gain cannot be obtained with the drive current set for wavelength λ ₂ due to the band filling effect, and the target output light level cannot be achieved. . At least, it is a problem to control the output of the optical amplifying device to a target constant value for the burst signal input in the wavelength range assumed by the system.

  Accordingly, in order to solve the above-described problems, the present invention provides an optical amplifying apparatus capable of controlling the level of an output signal to be a target value when a burst signal input in a wavelength range assumed by the system is amplified by the SOA, and a control method therefor The purpose is to provide.

  In order to achieve the above object, the present invention detects the wavelength and light intensity of an input optical burst signal, and refers to a table describing the relationship between the input light intensity, output light intensity, and drive current of the SOA for each wavelength. Therefore, the function to perform feedforward control is provided.

Specifically, the optical amplification device according to the present invention is:
A semiconductor optical amplifier (SOA) that amplifies an input burst signal according to a drive current and outputs an output burst signal;
A drive circuit for supplying the drive current to the SOA;
An input wavelength detection circuit for detecting the wavelength of the input burst signal;
An input light intensity detection circuit for detecting the light intensity of the input burst signal;
The correspondence relationship between the drive current, the light intensity of the input burst signal, and the light intensity of the output burst signal is stored for each wavelength of the input burst signal, and the wavelength of the input burst signal detected by the input wavelength detection circuit The drive circuit determines a value of the drive current for amplifying the output burst signal to a desired light intensity according to the light intensity of the input burst signal detected by the input light intensity detection circuit based on the correspondence relationship A control circuit for instructing
Is provided.

In addition, a method for controlling an optical amplifying device according to the present invention includes a semiconductor optical amplifier (SOA) that amplifies an input burst signal according to a drive current and outputs an output burst signal,
A drive circuit for supplying the drive current to the SOA;
A method for controlling an optical amplifying apparatus comprising:
An input wavelength detection procedure for detecting the wavelength of the input burst signal;
An input light intensity detection procedure for detecting the light intensity of the input burst signal;
For each wavelength of the input burst signal, the correspondence relationship between the drive current, the light intensity of the input burst signal, and the light intensity of the output burst signal is stored, and the wavelength of the input burst signal detected by the input wavelength detection procedure and the wavelength The drive circuit determines a value of the drive current for amplifying the output burst signal to a desired light intensity according to the light intensity of the input burst signal detected in the input light intensity detection procedure based on the correspondence relationship A control procedure instructing to
I do.

  The optical amplifying device according to the present invention detects the wavelength and light intensity of an input optical burst signal, searches the table for the value of the SOA drive current that can be amplified to the desired output light intensity at the wavelength, and outputs this value to the drive circuit. To instruct. The present invention provides an optical amplifying apparatus capable of controlling the level of an output signal to be a target value when a burst signal input in a wavelength range assumed by the system is amplified by the SOA by performing feedforward control in this way, and the same A control method can be provided.

The optical amplification device according to the present invention further comprises an output light intensity detection circuit for detecting the light intensity of the output burst signal,
The control circuit includes:
A value of the correction drive current that determines the light intensity of the output burst signal detected by the output light intensity detection circuit as a desired light intensity is determined, and the value of the correction drive current is set to the value of the drive current instructed to the drive circuit Is superimposed.

  The optical amplifying device according to the present invention performs feedback control simultaneously with feedforward control, brings the SOA output closer to the target value by feedforward control, and compensates for a slight difference from the target value by feedforward control. The output light intensity can be stabilized.

  On the other hand, in order to achieve the above object, the present invention may be controlled only by the function of detecting the light intensity of the output optical burst signal and performing feedback control.

Specifically, the optical amplification device according to the present invention is:
A semiconductor optical amplifier (SOA) that amplifies an input burst signal according to a drive current and outputs an output burst signal;
A drive circuit for supplying the drive current to the SOA;
An input wavelength detection circuit for detecting the wavelength of the input burst signal;
An output light intensity detection circuit for detecting the light intensity of the output burst signal;
The correspondence relationship between the driving current and the light intensity of the output burst signal is stored for each wavelength of the input burst signal, and the wavelength of the input burst signal detected by the input wavelength detection circuit and the output light intensity detection circuit are detected. A control circuit that determines the value of the drive current at which the output burst signal is amplified to a desired light intensity according to the light intensity of the output burst signal based on the correspondence and instructs the drive circuit;
Is provided.

In addition, a method for controlling an optical amplifying device according to the present invention includes a semiconductor optical amplifier (SOA) that amplifies an input burst signal according to a drive current and outputs an output burst signal,
A drive circuit for supplying the drive current to the SOA;
A method for controlling an optical amplifying apparatus comprising:
An input wavelength detection procedure for detecting the wavelength of the input burst signal; an output light intensity detection procedure for detecting the light intensity of the output burst signal;
The correspondence relationship between the drive current, the light intensity of the input burst signal, and the light intensity of the output burst signal is stored for each wavelength of the input burst signal, and the wavelength of the input burst signal detected by the input wavelength detection circuit The drive circuit determines a value of the drive current for amplifying the output burst signal to a desired light intensity according to the light intensity of the output burst signal detected by the output light intensity detection circuit based on the correspondence relationship A control procedure instructing to
I do.

  The present invention detects the wavelength of the input optical burst signal, detects the output light intensity, and performs feedback control according to the wavelength. Since the present invention does not perform the feedforward control described above, there is no drive current based on feedforward. Therefore, if the difference between the input light intensity and the target value is large and the wavelength dependence of the SOA is not compensated, the drive current is insufficient on the short wavelength side and the input light intensity range in which the feedback circuit operates normally becomes narrow. On the other hand, there is a problem that the drive current becomes excessive and the feedback circuit is not stabilized. Therefore, the control circuit determines the drive circuit by comparing the wavelength detected by the input wavelength detection circuit and the output light intensity detected by the output light intensity detection circuit in feedback control with the correspondence relationship. The present invention provides an optical amplifying apparatus capable of controlling the level of an output signal to be a target value when a burst signal input in a wavelength range assumed by the system is amplified by the SOA by performing feedback control in this way, and the control thereof A method can be provided.

The first method for detecting the wavelength of the input burst signal is as follows. The input wavelength detection circuit of the optical amplification device according to the present invention is:
A first branching device for branching the input burst signal;
A second branching device that further branches the input burst signal branched by the first branching device;
An optical filter having a transmission characteristic in which the transmittance monotonously increases or decreases with respect to a wavelength change, and is disposed in a path of one input burst signal branched by the second branching unit;
The wavelength of the input burst signal from the ratio of the light intensity of one input burst signal branched by the second branching device and transmitted through the optical filter and the light intensity of the other input burst signal branched by the second branching device. A wavelength detector for detecting
It is characterized by having.

  In this case, the second branching unit has a light intensity after passing through the optical filter of one of the input burst signals branched by the second branching unit at the wavelength of the minimum transmittance of the optical filter and the second branching unit. It is preferable that the branching ratio is such that the light intensity of the other input burst signal branched by the branching unit is the same. The detection of the optical wavelength of the input burst light can be facilitated by the second branching device branching in consideration of the transmission of the optical filter.

A second method for detecting the wavelength of the input burst signal is as follows. The input wavelength detection circuit of the optical amplification device according to the present invention is:
A first branching device for branching the input burst signal;
A second branching device that further branches the input burst signal branched by the first branching device;
The transmittance is constant with respect to the wavelength change in the first wavelength range, and has a transmission characteristic in which the transmittance monotonously increases or decreases with respect to the wavelength change in the second wavelength range longer than the first wavelength range. A first optical filter disposed in a path of one input burst signal branched by the second branching unit;
In the first wavelength range, the transmittance monotonously increases or decreases with respect to the wavelength change in the first wavelength range, and the transmittance is constant with respect to the wavelength change in the second wavelength range. A second optical filter disposed in the path of the other branched input burst signal;
The light intensity of one input burst signal branched by the second branching device and transmitted through the first filter and the light intensity of the other input burst signal branched by the second branching device and transmitted through the second filter. A wavelength detector for detecting the wavelength of the input burst signal from a ratio;
It is characterized by having.
By employing this method, the operating wavelength range of the optical amplifying device can be expanded.

  The present invention can provide an optical amplifying apparatus capable of controlling the level of an output signal to a target value when a burst signal input in a wavelength range assumed by the system is amplified by the SOA, and a control method thereof.

It is a figure explaining the structure of the PON system using an optical amplifier. It is a figure explaining the optical amplifying device carrying the conventional SOA. It is a figure explaining the optical amplifier which concerns on this invention. It is a figure explaining the wavelength detection method in the optical amplifier which concerns on this invention. It is a figure explaining the preferable structure of the optical amplifier which concerns on this invention. It is a figure explaining the optical amplifier which concerns on this invention. It is a figure explaining the wavelength detection method in the optical amplifier which concerns on this invention. It is a figure explaining the optical amplifier which concerns on this invention.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are embodiments of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
FIG. 3 is a diagram illustrating the configuration of the optical amplifying device 301 of the present embodiment. The optical amplifying device 301 includes an SOA 11 that amplifies an input burst signal according to a drive current and outputs an output burst signal;
A drive circuit 12 for supplying a drive current to the SOA 11;
An input wavelength detection circuit for detecting the wavelength of the input burst signal, an input light intensity detection circuit for detecting the light intensity of the input burst signal, and
Stores the correspondence between the drive current, the light intensity of the input burst signal, and the light intensity of the output burst signal for each wavelength of the input burst signal, and detects the wavelength of the input burst signal detected by the input wavelength detection circuit and the input light intensity detection circuit. A control circuit 13 that determines a value of a drive current at which the output burst signal is amplified to a desired light intensity according to the light intensity of the input burst signal based on the correspondence relationship and instructs the drive circuit 12;
Is provided.

  Further, the optical amplifying device 301 includes a first branching device 14, a second branching device 15, an optical filter 16, a first photoelectric conversion device 17, and a second photoelectric conversion device 18.

Here, the input wavelength detection circuit is
A first branching device 14 for branching an input burst signal;
A second branching device 15 for further branching the input burst signal branched by the first branching device 14;
An optical filter 16 having a transmission characteristic in which the transmittance monotonously increases or decreases with respect to a wavelength change, and is disposed in the path of one input burst signal branched by the second branching device 15;
The wavelength of the input burst signal is determined from the ratio of the light intensity of one input burst signal branched by the second branching device 15 and transmitted through the optical filter 16 to the light intensity of the other input burst signal branched by the second branching device 15. A wavelength detector to detect;
Consists of. The optical filter 16, the first photoelectric converter 17, the second photoelectric converter 18, and the control circuit 13 function as an input wavelength detector.

  The input light intensity detection circuit includes a first photoelectric converter 17 and a control circuit 13.

  The first branching device 14 branches the input burst optical signal, and sends one to the SOA as the main signal and the other to the second branching device 15 as the monitor light. The second branching device 15 further branches the monitor light, and sends one to the first photoelectric converter 17 and the other to the optical filter 16. The first photoelectric converter 17 converts the sent monitor light into an electrical signal # 1. The optical filter 16 has a characteristic that the transmittance monotonously increases or decreases with respect to the wavelength change, transmits the other burst signal branched by the second branching device 15, and transmits it to the second photoelectric converter 18. send. The photoelectric conversion light converts the transmitted monitor light into an electric signal # 2.

  The control circuit 13 detects the light intensity and wavelength of the input burst signal based on the amplitude of the electrical signal # 1 and the amplitude of the electrical signal # 2, respectively. As shown in FIG. 4, at the point (A) in FIG. 3, the monitor light passes through the first branching device 14 and the second branching device 15 having no wavelength dependency, so that the monitor light has the light intensity of the input burst signal. Has proportional light intensity. On the other hand, at the point (B) in FIG. 3, the transmittance of the optical filter 16 monotonously increases or decreases as the wavelength changes (in the figure, the transmittance monotonously increases as the wavelength increases). The monitor light has a light intensity corresponding to the wavelength. Since the amplitude of the electrical signal that has been photoelectrically converted is proportional to the light intensity of the monitor light, the light intensity of the input burst signal can be detected from the amplitude of the electrical signal # 1, and the amplitude of the electrical signal # 1 and the electrical signal # 2 From this ratio, the wavelength of the input burst signal can be detected. The control circuit 13 performs these detections.

  Further, the control circuit 13 stores a table for the correspondence relationship between the SOA drive current, the input light intensity, and the output light intensity for each input wavelength. Based on the detected light intensity, wavelength, and table information, the control circuit 13 calculates a feedforward drive current in which the output light intensity output from the SOA becomes a preset target value, and uses the information as the drive circuit 12. Send to. The drive circuit 12 drives the SOA 11 with the calculated feedforward drive current.

  Here, the table included in the control circuit 13 is created based on results obtained in advance through experiments or the like. The table does not describe the values of the SOA drive current, input light intensity, and output light intensity for each input light wavelength, but describes the relationship between the input light intensity and gain for each input light wavelength. Also good.

(Embodiment 2)
FIG. 8 is a diagram illustrating the configuration of the optical amplifying device 302 of the present embodiment. The difference between the optical amplifying device 302 and the optical amplifying device 301 in FIG. 3 is that the optical amplifying device 302 further includes an output light intensity detection circuit that detects the light intensity of the output burst signal, and the control circuit 13 includes the output light intensity. The correction drive current value is determined so that the light intensity of the output burst signal detected by the detection circuit is a desired light intensity, and the value of the correction drive current is superimposed on the drive current value instructed to the drive circuit 12. . Here, the output light intensity detection circuit includes a third branch device 21, a third photoelectric converter 22, and a control circuit 13.

  The optical amplifying device 302 performs feedback control with the output light intensity detection circuit simultaneously with the feedforward control described in the optical amplifying device 301 of FIG. The optical amplifying device 302 can stabilize the output light intensity for a long time by bringing the output of the SOA 11 close to the target value by feedforward control and compensating for a slight difference from the target value by feedback control. In this case, since the difference is small, it is not necessary to use wavelength information in calculating the feedback drive current (corrected drive current).

(Embodiment 3)
The optical amplification device 302 in FIG. 8 may operate only by feedback control. That is, the optical amplifying device 302 amplifies the input input burst signal according to the drive current and outputs the output burst signal;
A drive circuit 12 for supplying a drive current to the SOA 11;
An input wavelength detection circuit for detecting the wavelength of the input burst signal, an output light intensity detection circuit for detecting the light intensity of the output burst signal, and
The correspondence relationship between the driving current and the light intensity of the output burst signal is stored for each wavelength of the input burst signal, and the wavelength of the input burst signal detected by the input wavelength detection circuit and the output light intensity detection circuit are detected. A control circuit 13 that determines a value of the drive current for amplifying the output burst signal to a desired light intensity according to the light intensity of the output burst signal based on the correspondence relationship and instructs the drive circuit 12;
Is provided.

  The control circuit 13 stores the correspondence between the drive current and the light intensity of the output burst signal for each wavelength. The control circuit 13 detects the wavelength of the input burst optical signal and the light intensity of the output burst optical signal. Then, the control circuit 13 determines the value of the drive current at which the light intensity of the output burst optical signal becomes the target value according to the wavelength of the input burst signal, and instructs the drive circuit 12.

(Embodiment 4)
This embodiment is a preferred form of the optical amplifying device 301 in FIG. 3 and the optical amplifying device 302 in FIG. The second branching unit 15 is configured to reduce the light intensity of the one input burst signal branched by the second branching unit 15 after passing through the optical filter and the second branching unit 15 at the wavelength of the minimum transmittance at the optical filter 16. This is a branching ratio in which the light intensity of the other branched input burst signal is the same.

  For example, assuming that the branching ratio of the second branching device 15 is 1: 1, the light intensity of the monitor light input to the second photoelectric converter 18 is the first light by the transmittance of the optical filter 16. It becomes smaller than the light intensity of the monitor light input to the electric converter 17 and it becomes difficult to detect the light intensity. Therefore, in the optical amplifying device of the present embodiment, the minimum transmittance (y dB) of the optical filter 16 and the branching ratio (x dB) of the second branching device 15 within the wavelength range assumed by the system are substantially the same. To do. By setting the branching ratio of the second branching device 15 in this way, the monitoring light to the first photoelectric conversion device 17 and the second photoelectric conversion device 18 (within the wavelength range assumed by the system, The input light intensity of the wavelength having the minimum transmittance can be made equal, and the light intensity can be easily detected. Here, y and x take negative values.

(Embodiment 5)
FIG. 6 is a diagram illustrating the configuration of the optical amplifying device 303 of the present embodiment. The wavelength detection circuits of the optical amplifying device 301 in FIG. 3 and the optical amplifying device 302 in FIG. 8 may be configured as follows. That is, the input wavelength detection circuit
A first branching device 14 for branching an input burst signal;
A second branching device 15 for further branching the input burst signal branched by the first branching device 14;
The transmittance is constant with respect to the wavelength change in the first wavelength range, and has a transmission characteristic in which the transmittance monotonously increases or decreases with respect to the wavelength change in the second wavelength range longer than the first wavelength range. , A first optical filter 16-1 disposed in the path of one input burst signal branched by the second branching device 15,
The transmittance monotonously increases or decreases with respect to the wavelength change in the first wavelength range, and has a transmission characteristic in which the transmittance is constant with respect to the wavelength change in the second wavelength range, and is branched by the second splitter 15. A second optical filter 16-2 disposed in the path of the other input burst signal;
The light intensity of one input burst signal branched by the second branching device 15 and transmitted through the first filter 16-1 and the other input burst signal branched by the second branching device 15 and transmitted through the second filter 16-2. A wavelength detector that detects the wavelength of the input burst signal from the ratio of the light intensity of
Consists of. The 1st optical filter 16-1, the 2nd optical filter 16-2, the 1st photoelectric converter 17, the 2nd photoelectric converter 18, and the control circuit 13 bear the function of a wavelength detection part. Further, the first optical filter 16-1, the second optical filter 16-2, the first photoelectric converter 17, the second photoelectric converter 18, and the control circuit 13 also function as an input light intensity detection circuit.

  The optical amplifying device 303 is substantially the same as the configuration of the optical amplifying device 301 in FIG. 3 except that an optical filter 16-1 is arranged in addition to the optical filter 16 (optical filter 16-2). 7A shows the light transmission characteristics of the optical filter 16-1, and FIG. 7B shows the light transmission characteristics of the optical filter 16-2. The optical filter 16-1 has a characteristic that the transmittance is constant in the wavelength band # 1, and the transmittance monotonously decreases in the subsequent wavelength band # 2. On the other hand, the optical filter 16-2 has a characteristic that the transmittance is constant in the wavelength band # 2, and the transmittance monotonously decreases in the subsequent wavelength band # 1.

  When the burst signal of wavelength band # 1 is input, the control circuit 13 detects the light intensity and wavelength of the input burst signal based on the ratio of the amplitude of the electrical signal # 2 to the amplitude of the electrical signal # 1, and the wavelength When the burst signal of band # 2 is input, the wavelength and light intensity of the input burst signal are detected based on the ratio of the amplitude of electrical signal # 1 to the amplitude of electrical signal # 2. By providing two optical filters having different transmission characteristics, the operating wavelength range of the optical amplifying device can be expanded.

  Note that the optical amplifying device 303 may have the feedback function described in FIG.

[Appendix]
The following is a supplement to the optical amplification device according to the present invention.
It is an object of the present invention to provide an optical amplifying apparatus that amplifies burst optical signals having different wavelengths and light intensities so as to have a target optical intensity.

(1): Consists of a first branching device, a second branching device, a first photoelectric conversion device, a second photoelectric conversion device, an optical filter 16, a control circuit 13, a drive circuit 12, and an SOA. An optical amplifying device that controls the light intensity of a burst signal to a constant target value at the output,
The first branching device branches an input burst signal,
The second branching device further branches the branched burst signal;
The first photoelectric converter converts one burst signal branched by the second branch into a first electrical signal,
The optical filter 16 has a characteristic that the transmittance monotonously increases or decreases with respect to a wavelength change, and transmits the other burst signal branched by the second branching device,
The second photoelectric converter converts the burst signal transmitted through the optical filter 16 into a second electrical signal,
The control circuit 13 detects the light intensity of the input burst signal from the amplitude of the first electric signal, and inputs the ratio of the amplitude of the first electric signal and the amplitude of the second electric signal. A burst signal wavelength is detected, and a table of the correspondence relationship between the SOA drive current, input light intensity, and output light intensity is stored for each input wavelength. Based on the detected light intensity, wavelength, and the table, In addition, a feedforward drive current in which the light intensity output from the SOA becomes a preset target value is calculated,
The drive circuit 12 sends a drive current corresponding to the calculated feedforward drive current,
The SOA is driven by the feedforward drive current.
An optical amplification device characterized by that.

(2): In the optical amplifying device described in (1) above, a third branching device and a third photoelectric converter are further arranged.
The third branching device branches the burst signal output from the SOA,
The third photoelectric converter converts the burst signal branched by the third branch into a third electrical signal;
The control circuit 13 detects the light intensity of the output burst signal from the amplitude of the third electric signal, calculates a feedback drive current that brings the detected light intensity close to a preset target value,
The drive circuit 12 sends a drive current obtained by superimposing the calculated feedback drive current on the feedforward drive current,
The SOA is driven by the feedback drive current.
An optical amplification device characterized by that.

(3): first branching device, second branching device, third branching device, first photoelectric conversion device, second photoelectric conversion device, third photoelectric conversion device, optical filter 16, An optical amplifying device that includes a control circuit 13, a drive circuit 12, and an SOA and controls the light intensity of an input burst signal to a constant target value at the output,
The first branching device branches an input burst signal,
The second branching device further branches the branched burst signal;
The first photoelectric converter converts one burst signal branched by the second branch into a first electrical signal,
The optical filter 16 has a characteristic that the transmittance monotonously increases or decreases with respect to a wavelength change, and transmits the other burst signal branched by the second branching device,
The second photoelectric converter converts the burst signal transmitted through the optical filter 16 into a second electrical signal,
The third branching device branches the burst signal output from the SOA,
The third photoelectric converter converts the burst signal branched by the third branch into a third electrical signal;
The control circuit 13 detects the light intensity of the input burst signal from the amplitude of the first electric signal, and inputs the ratio of the amplitude of the first electric signal and the amplitude of the second electric signal. Feedback for detecting the burst signal wavelength, further detecting the light intensity of the output burst signal from the amplitude of the third electrical signal, and bringing the detected light intensity closer to a preset target value according to the detected wavelength Calculate the drive current,
The drive circuit 12 sends out a drive current corresponding to the calculated feedback drive current,
The SOA is driven by the feedback drive current.
An optical amplification device characterized by that.

(4): In the optical amplifying device described in (1) to (3) above,
The minimum transmittance of the optical filter 16 within the wavelength range assumed by the system and the branching ratio of the other burst signal to the other burst signal branched by the second branching unit are substantially the same.
An optical amplification device characterized by that.

(5): The optical amplifying device according to the above (1) to (3) includes a second optical filter 16 in addition to the optical filter 16 (first optical filter 16).
The first optical filter 16 has a characteristic that the transmittance is constant in the first wavelength band, and the transmittance monotonously decreases in the second wavelength band that follows.
The second optical filter 16 has a characteristic that the transmittance is constant in the second wavelength band, and the transmittance monotonously decreases in the subsequent first wavelength band. Transmit one of the branched burst signals,
When the burst signal of the first wavelength band is input, the control circuit 13 determines the input burst signal based on the amplitude of the first electrical signal and the amplitude of the second electrical signal, respectively. When the light intensity and the wavelength are detected and the burst signal of the second wavelength band is input, the input is performed based on the amplitude of the first electric signal and the amplitude of the second electric signal, respectively. Detect wavelength of burst signal and light intensity,
An optical amplification device characterized by that.

  The optical amplifying device according to the present invention is a feedforward control optical amplifying device that controls the output to a constant value by changing the drive current of the SOA with respect to burst optical signal inputs having different intensities. Optical amplification independent of the signal wavelength is possible.

11: Semiconductor optical amplifier (SOA: Semiconductor Optical Amplifier)
12: drive circuit 13: control circuit 14: first branching device 15: second branching device 16: optical filter 16-1: first optical filter 16-2: second optical filter 17: first photoelectric converter 18: 2nd photoelectric converter 21: 3rd branch device 22: 3rd photoelectric converters 301-303: Optical amplifier

Claims (8)

A semiconductor optical amplifier (SOA) that amplifies an input burst signal according to a drive current and outputs an output burst signal;
A drive circuit for supplying the drive current to the SOA;
An input wavelength detection circuit for detecting the wavelength of the input burst signal;
An input light intensity detection circuit for detecting the light intensity of the input burst signal;
The correspondence relationship between the drive current, the light intensity of the input burst signal, and the light intensity of the output burst signal is stored for each wavelength of the input burst signal, and the wavelength of the input burst signal detected by the input wavelength detection circuit The drive circuit determines a value of the drive current for amplifying the output burst signal to a desired light intensity according to the light intensity of the input burst signal detected by the input light intensity detection circuit based on the correspondence relationship A control circuit for instructing
An optical amplification device comprising: An output light intensity detection circuit for detecting the light intensity of the output burst signal;
The control circuit includes:
A value of the correction drive current that determines the light intensity of the output burst signal detected by the output light intensity detection circuit as a desired light intensity is determined, and the value of the correction drive current is set to the value of the drive current instructed to the drive circuit The optical amplifying apparatus according to claim 1, wherein: A semiconductor optical amplifier (SOA) that amplifies an input burst signal according to a drive current and outputs an output burst signal;
A drive circuit for supplying the drive current to the SOA;
An input wavelength detection circuit for detecting the wavelength of the input burst signal;
An output light intensity detection circuit for detecting the light intensity of the output burst signal;
The correspondence relationship between the driving current and the light intensity of the output burst signal is stored for each wavelength of the input burst signal, and the wavelength of the input burst signal detected by the input wavelength detection circuit and the output light intensity detection circuit are detected. A control circuit that determines the value of the drive current at which the output burst signal is amplified to a desired light intensity according to the light intensity of the output burst signal based on the correspondence and instructs the drive circuit;
An optical amplification device comprising: The input wavelength detection circuit is
A first branching device for branching the input burst signal;
A second branching device that further branches the input burst signal branched by the first branching device;
An optical filter having a transmission characteristic in which the transmittance monotonously increases or decreases with respect to a wavelength change, and is disposed in a path of one input burst signal branched by the second branching unit;
The wavelength of the input burst signal from the ratio of the light intensity of one input burst signal branched by the second branching device and transmitted through the optical filter and the light intensity of the other input burst signal branched by the second branching device. A wavelength detector for detecting
The optical amplifying device according to claim 1, comprising: The second turnout
The light intensity of one input burst signal branched by the second branching device after passing through the optical filter and the other input burst branched by the second branching device at the wavelength of the minimum transmittance at the optical filter. 5. The optical amplifying apparatus according to claim 4, wherein the optical amplifier has a branching ratio that makes the signal light intensity the same. The input wavelength detection circuit is
A first branching device for branching the input burst signal;
A second branching device that further branches the input burst signal branched by the first branching device;
The transmittance is constant with respect to the wavelength change in the first wavelength range, and has a transmission characteristic in which the transmittance monotonously increases or decreases with respect to the wavelength change in the second wavelength range longer than the first wavelength range. A first optical filter disposed in a path of one input burst signal branched by the second branching unit;
In the first wavelength range, the transmittance monotonously increases or decreases with respect to the wavelength change in the first wavelength range, and the transmittance is constant with respect to the wavelength change in the second wavelength range. A second optical filter disposed in the path of the other branched input burst signal;
The light intensity of one input burst signal branched by the second branching device and transmitted through the first filter and the light intensity of the other input burst signal branched by the second branching device and transmitted through the second filter. A wavelength detector for detecting the wavelength of the input burst signal from a ratio;
The optical amplifying device according to claim 1, comprising: A semiconductor optical amplifier (SOA) that amplifies an input burst signal according to a drive current and outputs an output burst signal;
A drive circuit for supplying the drive current to the SOA;
A method for controlling an optical amplifying apparatus comprising:
An input wavelength detection procedure for detecting the wavelength of the input burst signal;
An input light intensity detection procedure for detecting the light intensity of the input burst signal;
For each wavelength of the input burst signal, the correspondence relationship between the drive current, the light intensity of the input burst signal, and the light intensity of the output burst signal is stored, and the wavelength of the input burst signal detected by the input wavelength detection procedure and the wavelength The drive circuit determines a value of the drive current for amplifying the output burst signal to a desired light intensity according to the light intensity of the input burst signal detected in the input light intensity detection procedure based on the correspondence relationship A control procedure instructing to
Control method to do. A semiconductor optical amplifier (SOA) that amplifies an input burst signal according to a drive current and outputs an output burst signal;
A drive circuit for supplying the drive current to the SOA;
A method for controlling an optical amplifying apparatus comprising:
An input wavelength detection procedure for detecting the wavelength of the input burst signal; an output light intensity detection procedure for detecting the light intensity of the output burst signal;
The correspondence relationship between the driving current and the light intensity of the output burst signal is stored for each wavelength of the input burst signal, and the wavelength of the input burst signal detected by the input wavelength detection circuit and the output light intensity detection circuit are detected. A control procedure for determining the value of the drive current for amplifying the output burst signal to a desired light intensity according to the light intensity of the output burst signal based on the correspondence and instructing the drive circuit;
Control method to do.

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