KR100366886B1 - Method for Burn-In in APC Mode Using Calibrated Internal Monitor Photo Diode - Google Patents

Abstract

The present invention relates to a method for evaluating reliability of a laser diode for ultra-high speed optical communication, comprising: a first step of checking whether LD is properly inserted by applying an electrical signal for each channel in a 25C ACC state; A second process of calculating the distribution of the point and the light output at which the laser output changes rapidly by analyzing the correlation with the light output while changing the current of the laser diode in the 25C ACC SCHMOO PLOT state; In the state of 85C APC, it monitors the electrical condition of laser diode to maintain the maximum output while applying the electrical adverse condition of the maximum laser beam output specification that LD is not destroyed. A third process of recording and recording the time when the life is over; A fourth step of calculating the distribution of the point and the light output at which the laser output is rapidly changed by analyzing the correlation with the light output while changing the current of the laser diode after the application time has elapsed due to the bad condition of the 85C ACC state; 25C ACC SCHMOO PLOT state! And a fifth step of calculating a distribution of the point and the light output at which the laser output changes rapidly by analyzing the correlation with the light output while changing the current of the laser diode. The reliability of the laser itself can be evaluated. In addition, it is possible to determine the presence or absence of the failure of the MPD has the effect of enabling accurate evaluation.

Description

Burn-In Method in Automatic Power Control Mode Using Photodiode Interval Monitor Calibration {Method for Burn-In in APC Mode Using Calibrated Internal Monitor Photo Diode}

The present invention relates to a method for evaluating the reliability of a laser diode for ultra-high speed optical communication. In particular, when producing a laser diode (LASER DIODE: LD) which is a key component of the ultra-high speed optical communication, the reliability is evaluated by using temperature and electrical adverse conditions used in the production site. The present invention relates to a burn-in driving method in an automatic power control mode using photodiode interval monitor calibration.

In general, in order to verify the reliability of the laser diode, an electrical stress is applied to the laser diode in addition to the temperature, and the method of applying the electrical stress is largely divided into two types.

The first is the Automatic Current Control (ACC) mode, which sends a constant current to the laser diode and monitors the amount of current so that a constant current always flows and the optical output of the laser diode or By continuously monitoring the laser beam, it records at what moment (hour) the output of the laser beam decreases or increases, and if the level is out of a certain amount, the laser diode is considered dead.

The second method is Automatic Power Control (hereinafter referred to as APC) mode, which sends a constant current to the laser diode and senses the intensity of the output laser beam so that the output level of the laser beam is applied as a reference. Change the amount of, so that the output of the laser beam is always at a certain level, and monitor the applied current to record at what moment (time) the current decreases or increases.If the level is out of a certain amount, the laser diode is dead. It is considered to be.

In this case, since the laser beam (light output) output is a main factor, the laser mainly uses the APC mode, and a high sensitivity external detector (PD) is used to measure the laser output.

However, the actual use condition is that the external PD cannot be used and the monitor PD (MPD) attached to the laser diode itself is used.

In other words, even if the laser itself passes the reliability test, if the attached MPD is bad (especially in terms of reliability), it will not only cost an expensive laser package module, but also it has not undergone the reliability of the MPD for temperature. Therefore, a problem arises in that it is difficult to precisely control light output and calculate the life of the laser.

An object of the present invention for solving the above problems is to evaluate the reliability using the temperature and electrical adverse conditions used in the production site when producing a laser diode (LASER DIODE: LD) in evaluating the reliability of the ultra-high speed optical communication laser diode. The present invention provides a burn-in driving method in an automatic power control mode using photodiode interval monitor calibration.

1 is an exemplary view for explaining a general laser diode measurement process

2 is an exemplary diagram illustrating a laser diode driving circuit as an exemplary diagram for describing a technical spirit applied to the present invention.

3A is an exemplary configuration diagram of an optical output detection circuit of an external laser diode

3B is an exemplary configuration diagram of an MPD laser power detection circuit.

4 is an example LD sample of the TO-CAN type (TYPE)

5 is a flowchart illustrating a procedure for explaining a regulation process in the ACC mode among the MPD application algorithm according to the present invention.

6 is an exemplary view illustrating a procedure for defining a rule in APC mode among MPD application algorithms according to the present invention.

7 is a flowchart illustrating a procedure for explaining a regulation process in the MPD mode of the MPD application algorithm according to the present invention.

A feature of the present invention for achieving the above object is a first process for accurately measuring an external PD, recording the value thereof, and outputting a laser beam that is a reference by the external PD to the measured laser as the measured external PD. and; A second step of storing the intensity of light detected by the MPD and adjusting the current of the laser diode to reach a measured value when applying the APC mode using the MPD; And a third step of performing statistical application using a high-precision STANDARD RESISTOR in the APC mode, calculating an error factor, and forcing in addition to the input value during the ACC mode current force. It is to include.

Another feature of the present invention for achieving the above object is to apply an external photodiode (EXTERNAL PD) for each wavelength of the wavelength (WAVELENGTH) on the basis of a high-precision laser source by applying a manual at regular intervals based on the certified laser source A first process of doing; The laser diode to be actually inspected is inserted into a facility to obtain and apply a corresponding Po using a certified laser diode current source and a power meter, and then apply the applied ACC current source to obtain a laser power of an external photodiode. Process; Although the value may vary depending on the LD current source accuracy and the JIG state / distance at the time of measurement, the third step is to obtain the applied factor of the external photodiode by compensating the read value under the condition that the laser beam angle does not deviate. .

Another feature of the present invention for achieving the above object is to apply an external photodiode (EXTERNAL PD) for each wavelength of the wavelength (WAVELENGTH) based on a high-precision laser source by applying a manual at regular intervals based on the certified laser source Applying a first step; The laser diode to be actually inspected is inserted into a facility to obtain and apply a corresponding Po using a certified laser diode current source and a power meter, and then apply the applied ACC current source to obtain a laser power of an external photodiode. Process; After inserting the laser diode to be measured using the current source and the external photodiode applied through the first and second processes, and applying a specific current in the ACC mode, the value read by the external photodiode is calculated as the already applied Po value. And a third process of calculating the Po of the MPD by reading the MPD current of the laser diode to be measured and converting it into the measured value of the external photodiode.

The above object and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings by those skilled in the art.

First, a technical concept applied to the present invention will be described with reference to the accompanying drawings.

1 is a graphical representation of the measurement of the laser diode, and the inside of the laser diode is composed of an LD that generates the actual laser beam and an MPD (Monitoring Photo Diode) that measures the intensity of the laser beam.

At this time, the electrical signal applied by the laser driving circuit is converted into a laser beam by the LD of the laser diode and the laser beam is transmitted to the external PD through the attenuator, which is in turn converted into an electrical signal by the laser power detection circuit.

At this time, the MPD inside the laser diode only applies thermal stress and is not included in the electrical stress and reliability verification items.

That is, the end user sets the output level of the laser beam using the MPD and uses the MPD to always preserve the laser light output. The correlation between the MPD and the laser under the temperature condition is ignored.

Therefore, as mentioned above, even if the laser itself passes the reliability test, the attached MPD is particularly defective in terms of reliability, and thus, the expensive laser package module is not used. Since it did not go through, it was difficult to precisely control light output and calculate the life of the laser.

Therefore, the present invention adds a circuit for detecting the output of the external diode described in FIG. 1 attached to the conventional laser diode driving circuit as shown in FIG. It is conceived that if the Burn-In operation is enabled, the above-mentioned problem can be solved.

Therefore, a brief description of the operation of a typical laser diode driving circuit of the configuration shown in FIG. 2 is that the amount of current applied by the computer is converted into an analog signal through a digital analog convertor (DAC), and passes through the circuit to the LD. When applied, an optical signal is generated at the laser diode. At this time, if the optical signal is not a certain amount, the applied current continues to increase, the optical reference at that time is the output of the external PD measured from the outside.

FIG. 3A is a diagram showing the configuration of an external photodiode optical output detection circuit added to the general laser diode driving circuit shown in FIG. 2 according to the present invention, and depicts a laser power detection circuit of an external PD or MPD. MPD is fed back inside the laser diode, so there is no attenuator, but the basic circuit is the same. That is, it has the structure as shown in the attached FIG. 3B.

Hereinafter, the test process of the LD in the burn-in process will be described.

First, when the ACC mode is checked at 25 ° C, the channel is checked by applying an electrical signal to determine whether the LD is properly inserted. If it is not plugged in correctly, reinsert the channel.

Secondly, the ACC SCHMOO PLOT process at 25 ° C is used to calculate the distribution of point and light output where the laser output changes rapidly by analyzing the correlation with the light output while changing the current of the laser diode.

Thirdly, it is a test method that sets the maximum bad condition among the actual use conditions and uses an external PD. When the APC mode is inspected at 85 ° C (the set temperature is different for each manufacturer), the electric bad condition is applied ( Maximum laser beam output specification that does not destroy LD) Monitor the electrical conditions of the laser diode to maintain maximum output. At this time, if the laser output power exceeds or falls below a certain standard during the bad condition application time (24 hours to 1000 hours; different for each type of product of each manufacturer), the dead time is recorded.

Fourthly, it is a test method that sets the maximum bad condition among actual use conditions and uses an external PD. When the ACC mode is inspected at 85 ° C (the set temperature is different for each manufacturer), By analyzing the correlation with the light output while changing the current of the laser diode, the distribution of the point and the light output at which the laser output changes rapidly is calculated.

Lastly, the second inspection process, that is, ACC SCHMOO PLOT process at 25 ° C., analyzes the correlation with the light output while changing the current of the laser diode to determine the point and light output where the laser output changes rapidly. Calculate the distribution.

4 is an exemplary LD sample of the TO-CAN type.

At this time, the external PD used for the reason that could not be applied in the existing method is artificially standardized by the system manufacturer to hold accurate measurement data. Therefore, the MPD is used as a reference for measuring the laser diode to be measured. The reason for this is that the measurement standard of the laser beam is lost when the reference is made as the object to be measured.

Therefore, the MPD application algorithm according to the present invention is as follows.

First, the external PD is accurately measured, the value is recorded, and the laser beam, which is a reference by the external PD, is outputted to the measured external PD.

At this time, the intensity of light detected by the MPD is stored and the current of the laser diode is adjusted to reach the measured value when the APC mode is applied using the MPD.

Referring briefly with reference to FIG. 5, a manual application is performed at regular intervals by applying the most basic laser diode current source. Accordingly, statistical application is performed using a high-precision STANDARD RESISTOR and an error factor is calculated to force an addition to the input value at the ACC mode current force.

In addition, referring briefly to FIG. 6, 1) manual application is applied at regular intervals based on the certified laser source. Based on the high-precision laser source, an external photodiode (EXTERNAL PD) is applied for each laser wavelength (WAVELENGTH).

2) Insert the laser diode to be tested into the equipment to obtain and apply Po using the certified laser diode current source and power meter and apply the applied ACC current source to obtain the laser power of the external photodiode. .

At this time, the value may vary depending on the LD current source accuracy and the JIG state / distance at the time of measurement, but the applied factor of the external photodiode is obtained by compensating the read value under the condition that the laser beam angle does not deviate.

In addition, referring briefly to FIG. 7, when a specific current is applied to the ACC mode after inserting a laser diode to be measured using the current source and the external photodiode applied by the process of FIG. The value read by the diode is calculated as the value of Po already applied, and then the MPD current of the laser diode as the measured object can be read and converted into the measured value of the external photodiode.

The MPD Po value obtained in this way is applied as a force value in the APC MPD mode, and the APC is driven by the MPD. This value is an applied value and there is only an applied error factor.

While the invention has been shown and described in connection with specific embodiments thereof, it is well known in the art that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the claims. Anyone who owns it can easily find out.

As described above, according to the present invention, when producing a laser diode (LASD DIODE: LD), which is a key component of high-speed optical communication, the reliability and reliability of the laser itself can be evaluated using temperature and electrical adverse conditions used in the production site. The failure of the MPD can be determined, and thus, the accurate evaluation is possible.

Claims (4)

A first step of checking whether the LD is properly inserted by applying an electrical signal to each channel in the 25C ACC state; A second process of calculating the distribution of the point and the light output at which the laser output changes rapidly by analyzing the correlation with the light output while changing the current of the laser diode in the 25C ACC SCHMOO PLOT state; In the state of 85C APC, it monitors the electrical condition of laser diode to maintain the maximum output while applying the electrical adverse condition of the maximum laser beam output specification that LD is not destroyed. A third process of recording and recording the time when the life is over; A fourth step of calculating the distribution of the point and the light output at which the laser output changes rapidly by analyzing the correlation with the light output while changing the current of the laser diode after an application time has elapsed due to a bad condition of the 85C ACC state; 25C ACC SCHMOO PLOT state! And a fifth process of calculating the distribution of the point and the light output at which the laser output changes rapidly by analyzing the correlation with the light output while changing the current of the laser diode. Burn-in method in automatic power control mode. A first step of accurately measuring the external PD, recording the value thereof, and outputting a laser beam which is a reference by the external PD to the measured laser as the measured external PD; A second step of storing the intensity of light detected by the MPD and adjusting the current of the laser diode to reach a measured value when applying the APC mode using the MPD; And In the APC mode, the third process of performing statistical application using a high-precision STANDARD RESISTOR, calculating an error factor, and adding it to the input value at the ACC mode current force is performed. And a burn-in method in an automatic power control mode using a photodiode interval monitor calibration. A first step of applying an external photodiode (EXTERNAL PD) for each wavelength of the laser (WAVELENGTH) based on a high-precision laser source by applying a manual at a predetermined cycle based on the certified laser source; The laser diode to be actually inspected is inserted into a facility to obtain and apply a corresponding Po using a certified laser diode current source and a power meter, and then apply the applied ACC current source to obtain a laser power of an external photodiode. Process; Although the value may change depending on the LD current source accuracy and the JIG state / distance at the time of measurement, the third step is to obtain the applied factor of the external photodiode by compensating the read value under the condition that the laser beam angle does not deviate. Burn-in method in automatic power control mode using photodiode interval monitor calibration. A first step of applying an external photodiode (EXTERNAL PD) for each wavelength of the laser (WAVELENGTH) based on a high-precision laser source by applying a manual at a predetermined cycle based on the certified laser source; The laser diode to be actually inspected is inserted into a facility to obtain and apply a corresponding Po using a certified laser diode current source and a power meter, and then apply the applied ACC current source to obtain a laser power of an external photodiode. Process; After inserting the laser diode to be measured using the current source and the external photodiode applied through the first and second processes, and applying a specific current in the ACC mode, the value read by the external photodiode is calculated as the already applied Po value. And a third process of reading the MPD current of the laser diode as a target to be measured and converting the measured value of the external photodiode to calculate the Po of the MPD. Burn-in method.