JP2006253752A - Optical transmitter, optical transmission system, and optical relaying apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmitter capable of carrying out data transmission without interruption even when any fault takes place in its light source. <P>SOLUTION: The optical transmitter includes: a first light source 11; a second light source 12 whose optical output can be adjusted; a monitor circuit 13 for monitoring optical outputs in total from the first and second light sources 11, 12 to adjust the optical output of the second light source 12 so that the total optical output is a prescribed value or over; and a delay circuit 14 for delaying the optical output of the first light source by a prescribed time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical transmission system that transmits data as an optical signal through an optical fiber, and more particularly to an optical transmitter that modulates light from a light source with data and outputs the optical signal as an optical signal.

  An optical transmitter cannot transmit an optical signal when its light output is reduced or extinguished due to a failure such as a failure of a light source or a lifetime.

  As means for solving this problem, a technique for preparing two light sources and a technique for duplicating a data transmission path have been proposed.

  For example, Patent Document 1 discloses an optical repeater. The optical repeater includes two light sources, a light source A as a current system and a light source B as a standby system. Normally, the working light source A is in operation, and if it fails, the operation is switched to the standby light source B to continue data transmission.

  Further, Patent Document 2 discloses an optical transmission terminal device. This device prepares two light sources and uses both light sources, for example, with a light output of 50% of the rated output of the light source. The light output is synthesized. The light output of both light sources is monitored, and when the light output decreases, the light output level of both light sources is adjusted, and the total value of the light output of both light sources is controlled to the desired value, even if one of the light sources is obstructed Even if this occurs, data transmission is continued.

  In addition, Patent Document 3 discloses a technique related to an illumination apparatus and an exposure apparatus, but discloses a technique that includes two light sources and adjusts the outputs of both light sources so that the combined light amount is constant.

JP-A-61-93737 Japanese Patent Application Laid-Open No. 9-116499 (Japanese Patent Application No. 7-293932) Japanese Patent Laid-Open No. 2001-307989

  However, since the decrease in the light output of the light source may occur abruptly, in the techniques disclosed in Patent Documents 1 to 3, detection of the decrease in the light output is delayed, and the light source that is currently in use has been waiting. Even if the light source is switched or the light output of another light source is increased, it cannot catch up with the decrease of the current light output or the total light output, and as a result, the desired light output level cannot be obtained for a short time. This is shown in FIG. When such an event occurs in the optical transmitter, there arises a problem that data transmission is interrupted.

  Therefore, an object of the present invention is to provide an optical transmitter that can perform data transmission without interruption even if any failure occurs in a light source.

  In an optical transmitter that modulates light from a light source according to data and outputs it as an optical signal, a total light output of the first light source, a second light source capable of adjusting the light output, and the first and second light sources. A monitoring circuit that monitors and adjusts the light output of the second light source so that the total light output becomes a predetermined value or more, and a delay circuit that delays the light output of the first light source by a predetermined time. An optical transmitter is obtained.

  According to the present invention, it is also possible to obtain an optical transmitter in which the predetermined time (t3) is longer than the time (t2) required for increasing the light output of the second light source.

  Further, according to the present invention, the time (t2) required for increasing the light output of the second light source may be the second light source after the monitoring circuit detects that the total light output is less than the predetermined value. Thus, an optical transmitter including a required time (t4) until the adjustment of the optical output is started is obtained.

  Furthermore, according to the present invention, an optical transmitter further including a coupler for combining the optical outputs of the first and second light sources can be obtained.

  In addition, according to the present invention, when the total light output of the second light source is greater than or equal to a predetermined value, an optical transmitter that provides a light output with a value smaller than the light output of the first light source can be obtained.

  Further, according to the present invention, when the total light output is equal to or greater than a predetermined value, the second light source can obtain an optical transmitter that is at rest.

  Furthermore, according to the present invention, the monitoring circuit can obtain an optical transmitter having a function of notifying the monitoring result.

  Further, according to the present invention, an optical transmitter having a plurality of combinations of the first light source and the delay circuit can be obtained.

  Furthermore, according to the present invention, an optical transmitter having a plurality of second light sources can be obtained.

  Furthermore, according to the present invention, there is provided an optical transmitter having an optical transmitter and an optical receiver connected to the optical transmitter via an optical fiber and having an input resistance greater than the maximum optical output of the optical transmitter. A transmission system is obtained.

  In addition, according to the present invention, an optical repeater including an optical signal receiving unit and an optical signal transmitting unit, the optical transmitting unit including an optical transmitter, is obtained.

  According to the present invention, since the intensity of the optical signal input to the modulator does not decrease even if the light output of the current first light source suddenly decreases due to a failure or the like, the data transmission can be continued without interruption. It can be carried out.

  The present invention relates to an optical transmitter that modulates light from a light source with data and outputs it as an optical signal, an optical transmission system having such an optical transmitter, or such an optical transmitter as an optical transmitter. The present invention relates to an optical repeater provided. This optical transmitter monitors the total light output of the active first light source, the spare second light source that can adjust the light output, and the first and second light sources, and the total light output. Has a monitoring circuit that adjusts the light output of the second light source so that becomes equal to or greater than a predetermined value, and a delay circuit that delays the light output of the first light source by a predetermined time.

  Hereinafter, an optical transmitter according to an embodiment of the present invention will be described with reference to the drawings.

  With reference to FIG. 1, the present optical transmitter 10 is applied to an optical transmission system having an optical transmitter 10 and an optical receiver 20 connected to the optical transmitter 10 via an optical fiber 30.

  The optical transmitter 10 modulates the light from the light source with the data obtained as an electrical signal and outputs it as an optical signal. The optical transmitter 10 is an auxiliary first active light source 11 and has a light output that can be adjusted. The total light output of the two light sources 12 and the first and second light sources 11 and 12 is obtained by monitoring monitor signals output by the respective light sources, and the second light source 12 is set so that the total light output becomes a predetermined value or more. Monitoring circuit 13 that adjusts the light output of the light source, coupler 15 that combines the light outputs of the first and second light sources 11 and 122, and the light from the coupler 15 is modulated according to data and output as an optical signal. And a modulator 16. The 1st and 2nd light sources 11 and 12 are comprised by the laser diode etc., for example.

  Note that the light output of the first light source 11 may be adjustable in the same manner as the second light source 12. In this case, the monitoring circuit 13 is configured to be able to adjust the light output of the first light source 11 in addition to the second light source 12. Then, when the total light output exceeds a predetermined value, the monitoring circuit 13 reduces the light output of any of the first and second light sources 11 and 12. On the other hand, when the light output of the first light source 11 decreases and the total light output decreases, the monitoring circuit 13 controls to increase the light output of the second light source 12.

  The monitoring circuit 13 also has a function of notifying the administrator of the device of the monitoring result.

  The optical transmitter 10 further includes a delay circuit 14 that delays the optical output of the first light source 11 by a predetermined time t3. The predetermined time t3 is longer than the time t2 required to increase the light output of the second light source 12. The time t2 required to increase the light output of the second light source 12 is a required time from when the monitoring circuit 13 detects that the total light output is less than a predetermined value until the light output of the second light source 12 starts to be adjusted. Includes t4.

  The second light source 12 produces a light output with a value smaller than the light output of the first light source 11 when the total light output is greater than or equal to a predetermined value. Alternatively, the second light source 12 is at rest when the total light output is greater than or equal to a predetermined value.

  Next, the operation of this optical transmitter will be described.

  During normal operation, data transmission is basically performed using the current first light source 11. The second light source 12 is a spare light source and normally stops light emission or outputs weak light. Here, description will be made assuming that weak light is output. Note that the lifetime of the light source generally depends on the level of light output. The second light source 12 emits light at a sufficiently weaker level than the first light source 11 or does not emit light at all, and therefore has a longer life than the first light source 11. Therefore, when the first light source 11 is deteriorated, the second light source 12 is also deteriorated, and the probability that a desired light output cannot be obtained is sufficiently low. In order to further improve the reliability, it is conceivable to increase the number of light sources.

  The monitoring circuit 13 performs control so that the total light output of the first light source 11 and the second light source 12 becomes a desired light output. The initial state is set so that the light output from the first light source 11 is increased and the light output from the second light source 12 is decreased.

  The light outputs of the first light source 11 and the second light source 12 are input to the coupler 15, and the coupler 15 outputs light obtained by combining the light outputs of the first light source 11 and the second light source 12. The output from the coupler 15 is input to the modulator 16. The modulator 16 modulates the optical signal with the input data, and outputs the modulated optical signal. The modulated optical signal is connected to the optical receiver 20 via the optical fiber 30 to perform data transmission.

  When the light output of the first light source 11 decreases during normal operation, the monitoring circuit 13 detects this. Since the monitoring circuit 13 performs control so that the sum of the light outputs of the first light source 11 and the second light source 12 has a desired intensity, the light output of the second light source 12 is increased as much as the first light source 11 decreases. The sum of the light outputs of the first light source 11 and the second light source 12 is set to a desired value.

  FIG. 2 shows the state of control when the light output of the first light source 11 is gently lowered. The monitoring circuit 13 outputs the light output state of the light source as a monitoring result signal, and notifies abnormality.

  On the other hand, when the light output of the first light source 11 rapidly decreases, as shown in FIG. 4, the decrease (required) time t1 of the light output of the first light source 11 is equal to that of the second light source 12. It is shorter than the time t2 required for the light output increase, that is, the time t2 required for the light output increase of the second light source 12 cannot catch up with the decrease of the light output of the first light source 11, and the desired light output is interrupted. Data transmission during this time cannot be guaranteed. It should be noted that the time t2 required for increasing the light output of the second light source 12 is from when the monitoring circuit 13 detects that the total light output is less than a predetermined value until the adjustment of the light output of the second light source 12 is started. The required time t4 is included (t4 is not shown).

  However, in the present invention, the delay circuit 14 is connected to the light output side of the first light source 11, and the time t3 for delaying the light of the first light source 11 is equal to the second light source 12 as shown in FIG. Therefore, the optical output input to the modulator 16 does not decrease. Therefore, data transmission is continuously performed without interruption.

  Note that the optical transmitter 10 can output the reception sensitivity (anti-input resistance) of the optical receiver 20 when the optical output from the optical transmitter 10 becomes larger than a desired value during the delay time t3. It should be ensured that it is larger than the maximum light output.

  In the embodiment described above, one working light source and one spare light source are used. However, two or more working light sources provided with a delay circuit may be used, and two or more spare light sources may be used. .

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made within the technical scope described in the claims. Needless to say. For example, in the optical repeater having an optical signal receiving unit and an optical signal transmitting unit, the configuration of the present invention can be applied as the optical transmitting unit.

  Furthermore, the present invention can be applied to all devices and systems that perform optical transmission, such as computers, exchanges, communication devices, and broadcasting devices, and is particularly suitable for devices that require reliability.

1 is a block diagram of an optical transmission system including an optical transmitter according to an embodiment of the present invention. It is a figure which shows operation | movement of the optical transmitter by the Example of this invention. It is a figure which shows operation | movement of the optical transmitter by the Example of this invention. It is a figure which shows operation | movement of the conventional optical transmitter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical transmitter 11 1st light source 12 2nd light source 13 Monitoring circuit 14 Delay circuit 15 Coupler 16 Modulator 20 Optical receiver 30 Optical fiber

Claims (11)

In an optical transmitter that modulates light from a light source with data and outputs it as an optical signal,
A first light source;
A second light source capable of adjusting the light output;
A monitoring circuit that monitors the total light output of the first and second light sources and adjusts the light output of the second light source so that the total light output is equal to or greater than a predetermined value;
An optical transmitter comprising: a delay circuit that delays an optical output of the first light source by a predetermined time.   The optical transmitter according to claim 1, wherein the predetermined time (t3) is longer than a time (t2) required for increasing the light output of the second light source.   The time (t2) required for increasing the light output of the second light source starts adjusting the light output of the second light source after the monitoring circuit detects that the total light output is less than the predetermined value. The optical transmitter according to claim 2, comprising a required time (t 4) until.   The optical transmitter according to claim 1, further comprising a coupler that synthesizes the optical outputs of the first and second light sources.   The light according to any one of claims 1 to 4, wherein the second light source has a light output having a value smaller than a light output of the first light source when the total light output is equal to or greater than the predetermined value. Transmitter.   5. The optical transmitter according to claim 1, wherein the second light source is stopped when the total light output is equal to or greater than the predetermined value. 6.   The optical transmitter according to claim 1, wherein the monitoring circuit has a function of notifying a monitoring result.   The optical transmitter according to claim 1, comprising a plurality of combinations of the first light source and the delay circuit.   The optical transmitter according to claim 1, comprising a plurality of the second light sources.   The optical transmitter according to any one of claims 1 to 9, and an optical receiver connected to the optical transmitter via an optical fiber and having an input resistance greater than a maximum optical output of the optical transmitter Optical transmission system. 10. An optical repeater including an optical signal receiving unit and an optical signal transmitting unit, wherein the optical transmitting unit includes the optical transmitter according to claim 1.

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