JP3700886B2 - Laser control device for optical communication and control method therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical communication laser control apparatus and its control method used in the field of optical communication using wavelength multiplexing.
[0002]
[Prior art]
In general, a laser used as a signal source for optical communication has the following characteristics.
1. The emission wavelength of the laser varies with the temperature of the laser.
2. When the laser temperature is low, the drive current required to obtain the same amount of light emission is small.
3. The laser applies ATC (automatic temperature control).
When a laser having the above characteristics is used for wavelength multiplexing optical communication, it is necessary to pay attention to the wavelength interval of the laser used.
[0003]
[Problems to be solved by the invention]
In a wavelength division multiplexing optical communication system that mixes and transmits optical signals of a plurality of wavelengths, two waves may overlap substantially the same wavelength when the wavelength of adjacent light changes.
In a system in which light is separated and received by an optical filter at a receiving unit, crosstalk with an adjacent line occurs due to a decrease in reception level and an overlap with the wavelength of adjacent light, thereby degrading communication line quality.
In the case of a batch reception method without using an optical filter, beat noise due to light mixing occurs around the frequency corresponding to the wavelength interval as the wavelength interval approaches, which also reduces the communication line quality. Deteriorate.
During normal use, the temperature of the laser is kept stable by the temperature adjustment function by the ATC, but a problem occurs immediately after the power is turned on from the power-off state.
[0004]
Immediately after turning on the power, the ATC is not working sufficiently and the laser temperature is not stable.
At this stage, the emission wavelength may deviate from a predetermined value, and there is a possibility that communication will be adversely affected for several milliseconds to several seconds until the temperature stabilizes.
In view of this, conventionally, measures have been taken to allow for a transmission failure during that time, or to ensure that the wavelengths do not overlap at the time of start-up immediately after turning on the power with a large wavelength interval.
The wavelength range in which the laser can emit light is limited, and an optical amplifier is used for signal transmission in the 1550 nm band, but the bandwidth of the optical amplifier is also limited.
Therefore, if the wavelength interval is wide, the number of lasers that can emit light simultaneously is limited.
[0005]
The present invention solves the above-described problems, and provides a control device and a control method for an optical communication laser that do not adversely affect the adjacent emission wavelength at the time of startup immediately after turning on the power as well as during normal light emission. It is intended to provide.
[0006]
[Means for Solving the Problems]
The present invention has the following means in order to solve the above problems.
[0007]
According to a first aspect of the present invention, there is provided an optical communication laser control device comprising: a normal light output stabilizing circuit that stabilizes the light output of a laser at a normal light output level; and a laser having a level lower than the normal light output level. A spare light output stabilizing circuit for stabilizing the light output; a current detection mechanism for detecting the driving current of the laser; and a circuit switcher for switching from the spare light output stabilizing circuit to the regular light output stabilizing circuit. It is characterized by.
[0008]
The optical communication laser control apparatus according to claim 2 of the present invention is such that the optical output level of the standby optical output stabilization circuit for stabilizing the optical output of the laser is about 1/10 to 1/3 of the normal optical output level. It is a range.
[0009]
According to a third aspect of the present invention, there is provided an optical communication laser control method comprising: a normal light output stabilizing circuit that stabilizes the light output of a laser at a normal light output level; and a laser having a level lower than the normal light output level. The auxiliary light output stabilizing circuit for stabilizing the light output and a current detection mechanism for detecting the driving current of the laser, and at the time when the driving of the laser is started, the light of the laser is output by the auxiliary light output stabilizing circuit. The output is controlled, and after the current detection mechanism detects that the laser drive current has entered a predetermined value, the laser output is controlled by switching to the normal light output stabilization circuit. .
[0010]
According to a fourth aspect of the present invention, there is provided an optical communication laser control device wherein the optical output level of the auxiliary optical output stabilizing circuit for stabilizing the optical output of the laser is about 1/10 to 1/3 of the normal optical output level. It is a range.
[0011]
According to the control device and the control method for an optical communication laser of the present invention, a spare light output stabilizing circuit and a regular light output stabilizing circuit are provided as circuits for stabilizing the laser light output, and the spare light output is provided. Since the stabilization circuit stabilizes the laser light output to a level smaller than the normal light output level, the laser light is reduced to a level lower than the normal light output level when the laser drive is started. The optical output is stabilized by a standby optical output stabilization circuit that stabilizes the output. Since the temperature of the laser is not stable at the start of driving, even if the emission wavelength fluctuates outside a predetermined value, the level of the light output is small, so that the adjacent emission wavelength is not adversely affected.
After the light output from the standby light output stabilization circuit is stable and the laser drive current has entered the specified value, the current detection mechanism detects that the laser output current has been switched to the normal light output stabilization circuit. Light output. Since the laser is raised to a predetermined temperature by the preliminary light output stabilization circuit, even if the light output level becomes a regular light output, it becomes a stable light emission state that does not adversely affect the adjacent light emission wavelength. ing.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an optical communication laser control device and a control method thereof according to the present invention will be described below in detail with reference to FIGS.
In FIG. 1, 1 is a laser, 2 is a laser drive current detector, 3 is a control circuit switch, 4 is a regular light output stabilization circuit, 5 is a spare light output stabilization circuit, and 6 is a light output level detector. .
The regular light output stabilization circuit 4 is a control circuit for the laser 1 to output a regular predetermined light output level in a stable light emission state, and has a circuit configuration as shown in FIG. 2, for example.
In FIG. 2, 21 is a photodetector, 22 is an amplifier, 23 is a comparison amplifier, 24 is a laser diode, and 25 is an output level control unit. The photodetector 21 and the laser diode 24 are optically coupled within the module.
[0013]
The auxiliary light output stabilization circuit 5 stabilizes the light output of the laser 1 at a level smaller than the light output of the normal light output stabilization circuit 4. For example, in this embodiment, the spare light output stabilization circuit 5 is 1/1 of the normal predetermined light output level. It is about 10.
The control circuit switching unit 3 switches from the standby light output stabilization circuit 5 to the regular light output stabilization circuit 4 based on the current detection value of the laser drive current detector 2.
The optical output level detector 6 detects the optical output level of the laser 1 and feeds back the detection result to the normal optical output stabilization circuit 4 and the standby optical output stabilization circuit 5 to stabilize the respective optical output levels. is there.
[0014]
The optical communication laser control apparatus configured as described above is driven as follows.
In the initial start-up state in which the laser 1 is driven by turning on the power from the state in which the laser 1 is not emitting light, the power is turned on while the control circuit switch 3 is switched to the auxiliary light output stabilization circuit 5.
The spare light output stabilization circuit 5 sets the light output of the laser 1 to a level smaller than the normal light output level, for example, about 1/10 of the normal predetermined light output level in this embodiment. Since the temperature of the laser 1 is low in the initial state at the time of start-up, a predetermined light output level can be obtained with a small driving current.
[0015]
By the way, since the temperature of the laser 1 itself becomes higher when the laser 1 elapses for a predetermined time, in order to obtain the same light output level as that at the initial startup, a driving current larger than that at the initial startup is required. The laser drive current detector 2 detects the drive current of the auxiliary light output stabilization circuit 5 and switches the control circuit when the drive current reaches a preset value, that is, when the temperature of the laser 1 itself reaches a predetermined temperature. The device 3 switches to the normal light output stabilization circuit 4.
By switching to the normal light output stabilization circuit 4, the light output of the laser 1 becomes a normal light output level. At this time, the temperature of the laser 1 has reached a predetermined temperature, so that the wavelength of the emitted light is Since the light does not fluctuate, the light emission is stable without adversely affecting the adjacent light emission wavelength. Hereinafter, the light output of the laser 1 is controlled to a stable light emission state by the normal light output stabilization circuit 4.
[0016]
FIG. 3 is a circuit example showing a specific embodiment of the laser control apparatus for optical communication.
In FIG. 3, 31 is a laser diode, 32 is a laser drive current detector, 33 is a control circuit switching unit, 34 is a normal light output controller, 35 is a spare light output controller, and 35 is a light output level detector.
[0017]
【The invention's effect】
As described above, according to the optical communication laser control device and the control method therefor of the present invention, the preliminary optical output stabilization circuit and the regular optical output stabilization circuit are provided as circuits for stabilizing the optical output of the laser. The standby light output stabilization circuit stabilizes the laser light output to a level smaller than the normal light output level. The optical output is stabilized by a preliminary optical output stabilization circuit that stabilizes the optical output of the laser to a small level.
[0018]
Since the temperature of the laser is not stable at the start of driving, even if the emission wavelength fluctuates outside a predetermined value, the level of the light output is small, so that the adjacent emission wavelength is not adversely affected.
After the light output from the standby light output stabilization circuit is stable and the laser drive current has entered the specified value, the current detection mechanism detects that the laser output current has been switched to the normal light output stabilization circuit. Light output. Since the laser is raised to a predetermined temperature by the auxiliary light output stabilization circuit, even if the light output level becomes a normal light output, it becomes a stable light emission state that does not adversely affect the adjacent light emission wavelength. ing.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a control device for a laser for optical communication according to the present invention.
2 is a schematic diagram showing an example of a regular light output stabilization circuit used in the optical communication laser control device of FIG. 1. FIG.
3 is a specific circuit configuration diagram showing an embodiment of the optical communication laser control device of FIG. 1; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser 2 Laser drive current detector 3 Control circuit switching device 4 Regular light output stabilization circuit 5 Preliminary light output stabilization circuit 6 Light output level detector

Claims (4)

A normal light output stabilizing circuit that stabilizes the light output of the laser to a normal light output level; a standby light output stabilizing circuit that stabilizes the light output of the laser to a level smaller than the normal light output level; and the laser. An optical communication laser control device comprising: a current detection mechanism for detecting a drive current of the optical signal; and a circuit switcher for switching from the standby light output stabilization circuit to the regular light output stabilization circuit. 2. The optical communication according to claim 1, wherein the optical output level of the auxiliary optical output stabilizing circuit for stabilizing the optical output of the laser is in the range of about 1/10 to 1/3 of the normal optical output level. Laser control device. A normal light output stabilizing circuit that stabilizes the light output of the laser to a normal light output level; a standby light output stabilizing circuit that stabilizes the light output of the laser to a level smaller than the normal light output level; and the laser. A current detection mechanism that detects the drive current of the laser, and at the time when the drive of the laser is started, the preliminary light output stabilization circuit controls the light output of the laser, and the laser drive current enters a predetermined value. After detecting this by the current detection mechanism, the control method of the laser for optical communication is characterized in that the optical output of the laser is controlled by switching to the normal light output stabilization circuit. 4. The optical communication according to claim 3, wherein the optical output level of the auxiliary optical output stabilizing circuit for stabilizing the optical output of the laser is in the range of about 1/10 to 1/3 of the normal optical output level. Laser control method.

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