JP2000196184A - Laser diode module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress increase in cost due to increase in the parts and facilities of a spare system. SOLUTION: A laser diode module is provided with two LDs(laser diodes) 11 and 12, optical parts for outputting the output light of the LDs 11 and 12 from one portion, PDs(photodiodes) 13 and 14 for monitoring the light output of the LDs 11 and 12, a control circuit 15 for deciding the deterioration of the LDs by monitoring currents A and B and for generating a switching command signal fro switching the LD to be used, and a switching circuit 16 for switching and supplying a drive current toward the laser diode which is about to be used from now, based on the switching command signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser diode module having a laser diode (LD) as a light source.

[0002]

2. Description of the Related Art In high-speed and long-distance data transmission in an information processing apparatus, an optical device is generally used, and a laser diode (hereinafter, referred to as "LD") is often used as a light source. However, since the LD deteriorates faster than other electronic components, the reliability of the optical communication system is often increased by making the optical device redundant.

[0003]

However, in an optical device, the light source portion including the LD occupies a large part of the cost of the entire optical communication system. Therefore, the increase in cost due to the increase in spare parts and equipment is as small as possible. It is desired to suppress it.

An object of the present invention is to provide a laser diode module capable of minimizing an increase in cost due to an increase in spare parts and equipment in view of the above circumstances.

[0005]

According to a first aspect of the present invention, there is provided a laser diode module comprising: a plurality of laser diodes; an optical component for outputting output light of the plurality of laser diodes from a single location; Monitoring means for monitoring the optical output of the laser diode, laser diode deterioration determining means for determining the deterioration of the laser diode being monitored by monitoring the monitor output of the monitoring means, and the means for determining the deterioration of a certain laser diode. In this case, a switching command signal generating means for generating a switching command signal for switching a laser diode to be used to another laser diode, and a laser diode driving current based on the switching command signal, will be used from now on. A drive current supply destination switching means for switching and supplying the laser current to the laser diode. The features.

According to a second aspect of the present invention, there is provided a laser diode module according to the first aspect, wherein the laser diode driving current is feedback-controlled in accordance with the output of the monitor means.

According to a third aspect of the present invention, in the laser diode module according to the first or second aspect, when the laser diode to be used is switched, the laser diode to be used is simultaneously driven with the laser diode to be used. It is characterized by supplying a current.

According to a fourth aspect of the present invention, in the laser diode module according to the third aspect, at the time of switching the laser diode, a drive current is simultaneously supplied to the laser diode to be used and the laser diode that has been used up to now. Sometimes, the drive current of the laser diode is controlled so that a value obtained by adding the monitor output of the laser diode used up to now and the monitor output of the laser diode to be used from now on becomes a constant level. .

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 and FIG. 2 are views showing the configuration of an embodiment of a laser diode module (hereinafter, referred to as an “LD module”) according to the present invention. In this embodiment, a case is shown in which the LD module 1 includes two LDs 11 and 12. In the case where three or more LDs are provided, the input of the control circuit 15, the current adding circuit 17, and the output of the switching circuit 16 may be expanded by increasing the number of LDs.

Referring to FIG. 2, the LD module 1 comprises:
Two LD11 and LD12, and each LD11, 1
2. Photodiode for monitoring the optical output (corresponding to monitoring means, abbreviated as “PD” hereinafter) 1
3 and 14 and monitor currents A and B output from the PDs 13 and 14 are monitored.
Judgment of deterioration of 11, 12 and LD
A control circuit (corresponding to a laser diode deterioration determining means and a switching command signal generating means) 15 for outputting a switching command signal for switching a supply destination of a driving current from a driver; an LD 11 corresponding to the switching command signal; Switching circuit (drive current supply destination switching means) 16
And a current adding circuit 17 for adding a monitor current fed back to the LD driver to control the drive current so that the optical output levels of the LDs 11 and 12 become constant.
In order for the output light of each of the LDs 11 and 12 to be input to the core 101 of the optical fiber 100,
And an optical component 18 for outputting the output light from one place.

PD13 and PD14 are LD11 and LD1.
2 and outputs an electric signal proportional to the light output level as a monitor current A and a monitor current B, respectively.
These monitor currents A and B are used for the LD driver to perform feedback control of the drive current in order to keep the optical output levels of the LDs 11 and 12 that are liable to fluctuate due to changes in temperature and power supply voltage.

The control circuit 15 controls the currently driven LD 1
The monitor current A (or B) of 1 (or LD12) is monitored, and the LD11 (or LD12) deteriorates,
When the monitor current A (or monitor current B) decreases to a predetermined level, the LD11 (or LD1)
2) determines that the LD 12 cannot be used, outputs a switching signal to the switching circuit 16 so as to use the next spare LD 12 (or LD 11), and after the switching, switches to the newly driven LD 12
Monitor the monitor current B (or monitor current A) of (or the LD 11). Further, another spare LD 12 (or L
When switching to D11), do not switch to LD11 (or LD12) that is already unusable.

The switching circuit 16 switches the driving current of the LD driver so as to be input to the LD 11 (or LD 12) on the side to be operated in accordance with the switching signal from the control circuit 15. The switching circuit 16 closes the circuit to the LD 11 (or LD 12) so that the deteriorated LD 11 (or LD 12) and the spare LD 12 (or LD 11) emit light simultaneously for a certain period of time at the time of switching between the LDs 11 and 12. Alternatively, it operates to open the circuit to the LD 11). This can prevent transmission data from being lost due to an instantaneous interruption at the time of switching.

The optical component 18 is used to easily and efficiently couple the optical output of each LD to the core of the optical fiber.

Next, the operation will be described. Here, LD12
Will be described as a spare. FIG. 3 shows L
FIG. 7 schematically shows a lapse of time until D11 deteriorates and is switched to LD12, and changes in the optical output level of each LD and the total sum of each monitor current. Hereinafter, the operation will be described along the time shown in this figure.

Until the LD 11 starts to deteriorate (t0),
The control circuit 15 monitors the monitor current A, and controls the switching circuit 16 so that the drive current from the LD driver is also input to the LD 11. At this time, since the LD 12 has not yet emitted light, only the monitor current A is fed back from the current adding circuit 17 to the LD driver.

When the deterioration of the LD 11 progresses (t1) and the monitor current A decreases, the control circuit 15 determines that the LD 11 is unusable, and changes the LD to be driven from LD 11 to LD 12
, A switching signal is output to the switching circuit 16.

When the switching circuit 16 receives this switching signal, it first drives the LD 12 at time t1, and then stops the LD 11 at time t2. That is, between the time t1 and the time t2, the two LDs 11 and 12 emit light simultaneously. During this time, each LD 1
Since the sum of the monitor currents A and B of 1 and 12 is fed back to the LD driver, if the characteristics of PD 13 and PD 14 are the same, the LD driver adjusts the sum of the optical outputs of the LDs 11 and 12 to be constant. Control the drive current.

Therefore, when the LD 12 emits light, the monitor current B is generated, so that the drive current decreases and the light output level of the LD 11 that has started to deteriorate decreases. But,
In such an LD switching method, there is no instantaneous interruption of optical output, so that transmission data is not lost.

When the switching to the LD 12 is completed, (t
2) Since the LD 11 does not emit light, the current adding circuit 17
Only the monitor current B is fed back to the LD driver. With the control circuit 15 and the switching circuit,
The LD 12 is driven until it is deteriorated.

By performing the above operations, the LD 1
If the lifetimes of the LD module 1 and the LD 12 are the same, the lifetime of the LD module as a device can be expected to be twice as long as that of a single LD.

The optical component 18 is provided in the LD module 1.
The optical output of each of the LDs 11 and 12 can be easily and efficiently coupled to the core 101 of the optical fiber 100.

[0023]

As described above, according to the laser diode module of the present invention, since a plurality of LDs and switching means for switching the LDs are provided, the life of the laser diode module can be reduced by using the laser diode module. In addition, it does not require a plurality of optical transmission lines for constructing a standby system for improving reliability. In addition, the use of optical components allows the output light to be easily and efficiently coupled to the core of the optical fiber. In addition, when the laser diode is switched, the degraded LD and the spare LD are simultaneously lit for a certain period of time to switch, thereby preventing the loss of transmission data due to the momentary interruption of the optical output. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a laser diode module according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a circuit configuration of the laser diode module according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating characteristics of a laser diode module according to an embodiment of the present invention over time at the time of laser diode switching.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 laser diode module 11, 12 laser diode 13, 14 photodiode (monitor means) 15 control circuit (laser diode deterioration determination means, switching command signal generating means) 16 switching circuit (drive current supply destination switching means) 18 optical component

Claims (4)

[Claims] 1. A plurality of laser diodes, an optical component for outputting output light of the plurality of laser diodes from a single location, a monitor for monitoring the optical output of each laser diode, and a monitor output of the monitor Laser diode deterioration determining means for determining the deterioration of the laser diode being monitored by monitoring the laser diode. When the means determines deterioration of a certain laser diode, the laser diode to be used is switched to another laser diode. A switching command signal generating means for generating a switching command signal for, based on the switching command signal, a drive current supply destination switching means for switching the laser diode drive current toward a laser diode to be used from now on, A laser diode module comprising: 2. The laser diode module according to claim 1, wherein a feedback control of a laser diode driving current is performed in accordance with an output of said monitor means. 3. The laser according to claim 1, wherein when switching the laser diode to be used, a drive current is simultaneously supplied to the laser diode to be used from now on and the laser diode to be used up to now. Diode module. 4. When switching the laser diode, when supplying a drive current to a laser diode to be used from now on and a laser diode to be used up to now, a monitor output of the laser diode to be used up to now is supplied. 4. The laser diode module according to claim 3, wherein a driving current of the laser diode is controlled so that a value obtained by adding a monitor output of a laser diode to be used from now on becomes a constant level.