JP4554238B2 - Optical transceiver - Google Patents

Description

The present invention relates to an optical transmitting and receiving equipment. For example, in connection with optical fiber transmission, particularly those available equipment for duplicating fiber line for transmission reliability.

In recent years, optical fiber transmission systems have become widespread, and optical fiber transmission has been used as a data transmission link not only for the backbone transmission network of communication carriers but also for ordinary computer networks.
In general, a link using an optical fiber bears a large amount of traffic, and thus requires reliability for ensuring communication of information.

As a means for achieving reliability, there is a method of avoiding communication interruption by duplicating the path against the breakage of the optical fiber line.
As an example, there is a configuration as shown in FIG.
The network node device 1 has ports 3a and 3b for inserting optical transceivers 2a and 2b.
The operations of the optical transceivers 2 a and 2 b are operated by the switch 4 in the network node device 1.

Optical fiber lines 5a and 5b are connected to the optical transceivers 2a and 2b, respectively.
Normally, the optical transceiver 2a is in an operating state, and communication is performed using the optical fiber line 5a.
When the network node apparatus 1 detects an abnormality in communication via the optical fiber line 5a, it is considered that an abnormality has occurred on the optical fiber line 5a, and the optical transceiver to be operated using the switch 4 is switched from 2a to 2b.

Thereby, the optical fiber line to be used is switched from 5a to 5b.
Here, the abnormalities that can be detected by the network node device 1 include a decrease in the optical input level, a clock extraction failure, a frame structure abnormality, an alarm from the opposite device, and the like.
Further, there is a method using an optical cross connect as disclosed in Patent Document 1 and a device having a plurality of optical transceivers.

This is an optical transceiver used when communication is interrupted by comparing the configuration of the ring communication network stored in each network node device with the current communication state of the optical fiber ring detected by the device. The communication path and the optical wavelength to be used are switched by changing (Tributary IF).
JP2003-143171

However, these methods have a problem in that the configuration of the apparatus is complicated, and it is necessary to perform complicated processing in the network node apparatus regarding switching of the optical fiber communication path.
For example, the configuration as shown in FIG. 5 requires two optical transceivers.

Further, the method as disclosed in Patent Document 1 requires a complicated mechanism such as an optical cross connect.
In either method, the switching control is performed by the network node device.

  In view of the background art described above, an object of the present invention is to realize stable path switching with a simple mechanism.

An optical transceiver according to claim 1 of the present invention for solving the above-described problems is
Optical transmission means capable of oscillating a plurality of optical wavelengths, optical reception means capable of receiving a plurality of optical wavelengths, monitoring means for detecting the light reception level of the wavelength received by the optical reception means , and the reception level set in advance A pair of optical transceiver devices having control means for performing control to switch the oscillation wavelength of the optical transmission means to another wavelength when it is detected by the monitoring means that the level has dropped below the level ;
A pair of passive elements connected to both ends of a plurality of optical fiber lines ,
An optical transceiver capable of bidirectional transmission through each of the plurality of optical fiber lines,
It said optical transceiver device each of said light transmitting means and said light receiving means, wherein the passive element is connected to said plurality of optical fiber lines through each said pair of optical transceiver device is opposed,
The passive elements associate different wavelengths as light wavelengths incident on the respective optical fiber lines, and wavelengths different from each other in the pair of passive elements as light wavelengths incident on one of the optical fiber lines. Are associated with each other.
In the initial state,
The control means of one of the optical transceiver apparatuses controls the oscillation wavelength of the optical transmission means of the own apparatus to a predetermined wavelength, so that the passive element on the own apparatus side corresponds to the optical fiber corresponding to the predetermined wavelength. While selecting the communication path to the track,
The control means of the other optical transceiver device controls the oscillation wavelength of the optical transmission means of the own device to a wavelength corresponding to the predetermined wavelength, so that the passive device on the own device side has the one optical transceiver. Select the communication path to the optical fiber line selected by the passive element on the device side,
When the monitor means detects that the received light level has dropped below a preset level,
The control unit of the one optical transceiver device changes the oscillation wavelength of the optical transmission unit of the own device from the predetermined wavelength to another wavelength, thereby changing the other wavelength to the passive element on the own device side. And switching the communication path to the optical fiber line corresponding to
The control unit of the other optical transceiver apparatus changes the oscillation wavelength of the optical transmission unit of the own apparatus to a wavelength corresponding to the other wavelength, thereby causing the one of the light elements to pass to the passive element on the own apparatus side. The communication path is switched to the optical fiber line switched by the passive element on the transceiver device side .

Optical transmitting and receiving apparatus according to claim 2 of the present invention for solving the aforementioned problems is the optical transceiver according to claim 1, wherein said light transmitting means, further comprising: a laser light source that oscillates a plurality of, at different wavelengths Features.

The optical transmission / reception apparatus according to claim 3 of the present invention for solving the above-described problem is the optical transmission / reception apparatus according to claim 1,
The light receiving means includes a plurality of light receivers and other passive elements for performing wavelength coupling and branching ,
The other passive elements guide light incident from the passive elements to the different light receivers corresponding to the wavelengths,
The said control means determines the said optical fiber line currently used by specifying the said light receiver currently receiving .

The optical transmission / reception apparatus according to claim 4 of the present invention for solving the above-described problems is the optical transmission / reception apparatus according to claim 1, 2 or 3,
When that prior Ki受 light level drops below a preset level detected by said monitoring means,
The control unit temporarily stops the optical output from the optical transmission unit for a predetermined time, and then changes the oscillation wavelength of the optical transmission unit from the stopped wavelength to another wavelength.

According to the present invention, a path can be switched using a passive element regardless of a complicated device such as an optical cross connect.
In addition, it is not necessary to use a plurality of optical transceivers when duplicating the path, and only one is required, so that the configuration is simplified.

Furthermore, since the determination of the light reception level is used as a means for detecting a communication state abnormality, the detection mechanism can be simplified, and a stable switching operation can be performed by temporarily stopping the light emission at the time of wavelength switching.
It is also possible to grasp the system operation state such as the operation state of the opposite device.

FIG. 1 shows functional blocks of an optical transceiver according to the present invention.
As shown in FIG. 1, the optical transceiver 2 c is inserted into the port 3 of the network node device 1.
The optical transceiver 2c controls the optical transmitter 6 by receiving the output of the optical transmitter 6, the optical receiver 7, the monitor circuit 8 connected to the optical receiver 7, and the monitor circuit 8 capable of transmitting at a plurality of wavelengths. The driver 9 and the interface circuit 10 with the port 3 are provided.

The interface circuit 10 generates a modulation signal to be given to the optical transmitter 6 based on a signal received from the network node device 1 via the port 3.
The interface circuit 10 has a function of shaping the signal output from the optical receiver 7 and sending it to the device 1 via the port 3.
Further, the interface circuit 10 receives power for driving the optical transceiver supplied from the port 3, notifies the network node device 1 of the operation state of the optical transceiver, and receives an optical transceiver drive control signal from the network node device 1. It may have functions such as receiving.

The monitor circuit 8 monitors the output of the optical receiver 7, uses the preset light reception level as a threshold value, and notifies the driver 9 when it detects that the level is lower than the threshold value. It has the function to do.
The driver 9 drives the optical transmitter 6 based on the modulation signal supplied from the interface unit 10, and receives information on the light reception level provided from the monitor circuit 8 and receives the oscillation wavelength of the optical transmitter 6. And a function for stopping the light output for a preset time.

The optical transmitter 6 and the optical receiver 7 are connected to the optical fiber lines 5 a and 5 b through the optical filter 11.
The optical filter 11 is a passive element having a wavelength dependency having a function of associating a wavelength of light incident on or emitted from the optical filter with an optical fiber emitted or incident.
As such passive elements, it is conceivable to apply an array type waveguide grating having a wavelength revolving property, a wavelength separation filter using a grating mirror, or an apparatus comprising an optical bandpass filter and an optical coupler.

A similar device is also connected to the other ends of the optical fiber lines 5a and 5b, and communication is performed between these opposing devices.
As described above, the path is duplexed using the optical fiber lines 5a and 5b.
The oscillation wavelength of the optical transmitter 6 can take a plurality of values, and the optical receiver 7 is sensitive to a plurality of wavelengths.
Here, for simplicity of explanation, it is assumed that the optical transmitter 6 can oscillate at two different wavelengths λ1 and λ2.

Further, it is assumed that the optical filter 11 associates the wavelengths λ1 and λ3 with the optical fiber line 5a and the wavelengths λ2 and λ4 with the optical fiber line 5b.
Further, it is assumed that the opposing optical communication devices can oscillate at two different wavelengths λ3 and λ4.
Here, in order to simplify the explanation, it is shown that only two paths of the optical fiber lines 5a and 5b are switched, but three or more paths may be used.

In the present invention, the number of paths can be increased according to the number of wavelengths that can be handled by the optical transmitter 6 and the number of optical fibers that can be connected to the optical filter 11.
The outline of the switching operation of the oscillation wavelength of the optical transmitter will be described below.

First, as an initial state of the present apparatus, the optical transmitter 6 oscillates at the wavelength λ1.
At this time, communication with the opposing optical communication device is performed using the optical fiber 5a as indicated by a solid line in the figure.
When optical fiber communication is normally performed, an optical signal from an optical communication device facing the optical receiver 7 is incident on the optical receiver 7, and the optical power is set to a preset threshold value sufficient for stable communication. That's it.

Assuming that the optical transmitter of the opposing optical communication apparatus oscillates at the wavelength λ3 in the initial state, communication is performed using the optical fiber line 5a as shown by the solid line in the figure.
Next, when communication is not normally performed due to breakage or the like of the optical fiber 5a used for optical communication, the optical power level of the wavelength λ3 incident on the optical receiver 7 first decreases.
When the monitor 8 that monitors the light level at any time detects that the light level has become smaller than a preset threshold value, the monitor 8 provides the driver 9 with information relating to the decrease in light level.

The driver 9 controls the oscillation of the optical transmitter 6 to be stopped for a preset time, and then to oscillate at the wavelength λ 2, triggered by a decrease in the optical level that is the information provided.
Since the optical filter 11 associates light of wavelength λ2 with the optical fiber line 5b, the subsequent optical signal is transmitted through the optical fiber line 5b as indicated by a broken line in the figure.

In the opposite optical communication apparatus, the same wavelength switching is performed, and if an optical signal having a wavelength λ4 is transmitted, communication is performed via the optical fiber line 5b as indicated by a broken line in the figure. Path switching is achieved.
Here, the reason why more stable switching can be realized by stopping the light output will be described.

When the present optical transceiver is used oppositely, if there is an instantaneous light level fluctuation such as misrecognition of the light level due to external noise or the like, or an instantaneous interruption of the optical fiber line, the present invention deals with the present invention. Only one side of such an optical transceiver starts switching, and there is a possibility that mismatch of optical lines to be used occurs.
As a countermeasure to this, when wavelength switching is performed, by temporarily stopping the optical output, the opposite optical transceiver intentionally detects a decrease in light level, and the opposite optical transceiver is also started to switch. Stable switching can be realized by switching both the optical transceivers.

The driver 9 is provided with a timer that operates for a preset time that is triggered by the information provided from the monitor 8 so that the wavelength is not switched until the timer expires. Try to suppress sensitive reactions to noise and interruptions.
Furthermore, a timer can be used to determine the time during which the driver 9 stops the optical output.

As described above, the abnormality of the optical communication state detected by the present apparatus is the most basic physical quantity in optical communication that the optical level is lowered, and the detection mechanism is simple.
In addition, switching of the optical communication path is performed with a simple configuration that is a combination of wavelength switching of the optical transmitter and passive elements.

The flow of the above operation is shown in FIG.
After the power-on step S1, light is first emitted at λ1 as shown in step S2.
At this time, the light reception level is monitored as in the conditional branch step S3, and if the light level is not less than the threshold value, the communication establishment step S4 is performed.
Even after the communication is established, the light level is continuously determined in the conditional branch step S3 as needed.
If the light level is less than or equal to the threshold value, the process proceeds to timer setting / starting step S5 to start the timer.

This timer is for observing whether or not a state in which the light level is equal to or lower than the threshold value is maintained for a certain period of time in order to suppress a sensitive response to an instantaneous fluctuation of the light level.
The observation is performed in step S6. If the light level becomes larger than the threshold value for a predetermined time, the process proceeds to communication establishment step S4.
If the timer expires in step S7 while the light level remains below the threshold for a certain period of time, the process proceeds to timer setting / starting step S8.

Then, in the light source emission stop step S9, the light output of λ1 is stopped, and the stop is maintained until the expiration of the timer is confirmed in the conditional branch of step S10.
After the timer expires, the light source starts to emit light at another wavelength λ2 in step S11, and the process proceeds to conditional branch step S3 again.
If it is not detected in step S3 that the light reception level is lower than the threshold value, the process proceeds to communication establishment step S4, and the switching is completed.

Here, if the steps S1 to S11 described above are realized independently by the driver 9 provided in the optical transceiver 2c, the network node device 1 itself becomes irrelevant to the path switching process, so that the configuration becomes simple.
The steps S1 to S11 described above may be executed by the driver 9 in response to an instruction from the network node device 1 via the interface 10, and are not limited to those realized by hardware, and are not limited to computer software. It may be realized with.

A first embodiment of the present invention is shown in FIG.
In the figure, 8a is a level monitor that detects the power level of light received by the optical receiver 7, 12a and 12b are laser light sources that are provided in the optical transmitter 6 and oscillate at different wavelengths λ1 and λ2, respectively. An optical coupler 13 guides the light from the laser light sources 12a and 12b to the same optical path.
If the level monitor 8a detects that the received light power is below a preset level, the driver 9 is notified of this.

The driver 9 operates one of the laser light sources 12a and 12b. When the driver 9 receives a notification from the level monitor 8a, the driver 9 switches the laser light sources 12a and 12b to be operated.
The optical filter 11 which is a passive element reroutes the path to one of the optical fiber lines 5a and 5b according to the wavelength.
By the above operation, switching to another path can be performed when the received light power level is low.

As described above, according to the present embodiment, the communication path switching process can be performed using the optical filter 11 which is a passive element, regardless of a complicated device such as an optical cross-connect.
Further, when duplicating the path, it is not necessary to use a plurality of optical transceivers, and only one optical transceiver 2c is required, so that the configuration becomes simple.

Furthermore, since the determination of the light reception level by the optical receiver 7 is used as a means for detecting a communication state abnormality, the detection mechanism can be simplified.
In addition, since the optical transmitter 6 stops light emission at the time of wavelength switching, a stable switching operation is possible.

A second embodiment of the present invention is shown in FIG.
In the figure, 14a and 14b are light receiving elements provided in the optical receiver 7, and 8b and 8c are monitor circuits connected to the light receiving elements 14a and 14b.
A wavelength combining / branching filter 11a provided in the optical receiver 7 has a function of emitting different wavelengths λ3 and λ4 in different directions.
In the optical receiver 7, the wavelength coupling / branching filter 11 a is installed so as to guide the light having the wavelength λ 3 to the light receiver 14 a and the light having the wavelength λ 4 to the light receiver 14 b.

When communication is performed normally, one of the wavelengths λ3 and λ4 transmitted from the opposite similar device is incident, as indicated by the solid or broken arrows in the figure.
That is, light is incident on one of the light receiving elements 14a and 14b.
By specifying the light receiving elements 14a and 14b that are receiving, it is possible to determine which one of the optical fiber lines 5a and 5b, which are duplexed optical lines, is used.

In addition, a trouble has occurred in any of the instants when switching is performed in a device (not shown) facing the network node device 1 illustrated, when the facing device is not operating, or in a redundant path. In some cases, no light is incident on either of the light receiving elements 14a and 14b.
Therefore, the operation state of the communication system can be estimated by analyzing the reception states of the light receiving elements 14a and 14b.

As described above, according to the present embodiment, the path can be switched using the optical filter 11 which is a passive element, regardless of a complicated device such as an optical cross connect.
Further, when duplicating the path, it is not necessary to use a plurality of optical transceivers, and only one optical transceiver 2c is required, so that the configuration becomes simple.
Furthermore, since the light reception level drop by the optical receiver 7 is used as an abnormality detection means, the detection mechanism can be simplified.
In addition, the optical transmitter 6 can perform a stable switching operation by once stopping light emission at the time of wavelength switching.
Furthermore, by analyzing the reception state of the light receiving elements 14a and 14b, it is possible to identify which one of the duplexed optical lines is used and to grasp the system operation state such as the operation state of the opposite device. .

  As described above, according to the present invention, the configuration of the network node device can be simplified and stable path switching can be performed.

  The present invention can be used as an optical fiber communication path switching method and apparatus.

It is a functional block diagram of the switching device of the optical fiber line by the suitable mode of the present invention. It is a flowchart which shows the switching method of the optical fiber track | line by the suitable aspect of this invention. It is a functional block diagram of the switching device of the optical fiber line concerning the 1st example of the present invention. It is a functional block diagram of the switching device of the optical fiber line concerning the 2nd example of the present invention. It is a functional block diagram which shows the example of the switching method of the conventional optical fiber track | line.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Network node apparatus 2, 2a, 2b, 2c Optical transceiver 3, 3a, 3b Port which inserts optical transceiver 4 Switch which switches optical transceiver 5a, 5b Optical fiber line 6 Optical transmitter 7 Optical receiver 8, 8a, 8b, 8c monitor circuit 9 driver 10 interface 11, 11a optical filter 12a, 12b laser light source 13 optical coupler 14a, 14b light receiving element S1 power-on step S2 light emission step at λ1 S3 conditional branching step by light reception level decrease detection S4 communication establishment step S5 Timer setting / starting step S6 Conditional branching step due to detection of decrease in received light level S7 Conditional branching step due to timer expiration S8 Timer setting / starting step S9 Light source emission stop step S10 Conditional branching step due to timer expiration S11 Wave Switching Light source emitting start step

Claims (4)

Optical transmission means capable of oscillating a plurality of optical wavelengths, optical reception means capable of receiving a plurality of optical wavelengths, monitoring means for detecting the light reception level of the wavelength received by the optical reception means , and the reception level set in advance A pair of optical transceiver devices having control means for performing control to switch the oscillation wavelength of the optical transmission means to another wavelength when it is detected by the monitoring means that the level has dropped below the level ;
A pair of passive elements connected to both ends of a plurality of optical fiber lines ,
An optical transceiver capable of bidirectional transmission through each of the plurality of optical fiber lines,
It said optical transceiver device each of said light transmitting means and said light receiving means, wherein the passive element is connected to said plurality of optical fiber lines through each said pair of optical transceiver device is opposed,
The passive elements associate different wavelengths as light wavelengths incident on the respective optical fiber lines, and wavelengths different from each other in the pair of passive elements as light wavelengths incident on one of the optical fiber lines. Are associated with each other.
In the initial state,
The control means of one of the optical transceiver apparatuses controls the oscillation wavelength of the optical transmission means of the own apparatus to a predetermined wavelength, so that the passive element on the own apparatus side corresponds to the optical fiber corresponding to the predetermined wavelength. While selecting the communication path to the track,
The control means of the other optical transceiver device controls the oscillation wavelength of the optical transmission means of the own device to a wavelength corresponding to the predetermined wavelength, so that the passive device on the own device side has the one optical transceiver. Select the communication path to the optical fiber line selected by the passive element on the device side,
When the monitor means detects that the received light level has dropped below a preset level,
The control unit of the one optical transceiver device changes the oscillation wavelength of the optical transmission unit of the own device from the predetermined wavelength to another wavelength, thereby changing the other wavelength to the passive element on the own device side. And switching the communication path to the optical fiber line corresponding to
The control means of the other optical transceiver device changes the oscillation wavelength of the optical transmission means of the own device to a wavelength corresponding to the other wavelength, thereby causing the passive element on the own device side to pass the one light. An optical transmission / reception apparatus , wherein a communication path is switched to the optical fiber line switched by the passive element on a transceiver apparatus side . The optical transceiver according to claim 1.
The optical transmitter / receiver includes a plurality of laser light sources that oscillate at different wavelengths. The optical transceiver according to claim 1.
The light receiving means includes a plurality of light receivers and other passive elements for performing wavelength coupling and branching ,
The other passive elements guide light incident from the passive elements to the different light receivers corresponding to the wavelengths,
The said control means determines the said optical fiber line currently used by specifying the said light receiver currently receiving, The optical transmission / reception apparatus characterized by the above-mentioned . The optical transceiver according to claim 1, 2, or 3,
When that prior Ki受 light level drops below a preset level detected by said monitoring means,
The optical transmission / reception apparatus characterized in that the control unit temporarily stops the optical output from the optical transmission unit for a predetermined time and then changes the oscillation wavelength of the optical transmission unit from the stopped wavelength to another wavelength.

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