KR102673727B1 - Optical transmitting apparatus and method for verifying and adjusting characteristics during operation - Google Patents

Abstract

The present invention improves optical transmission performance by identifying optical output characteristics by identifying eye patterns in a situation where an optical transmitting and receiving device for optical communication transmits data at high speed, and predicts lifespan by comparing it with the deterioration characteristics identified during production. It is about an optical transmission device and its operation method that can confirm and correct characteristics during operation to increase the stability and reliability of optical communication by enabling After transmission, the process of measuring the laser diode optical output when one of the plurality of measurement current values dividing the driving current range by increasing or decreasing the current at the next signal change point is divided into all measured current values for the driving current range. After understanding and combining the eye patterns, the optical output characteristic curve for the current of the laser diode is derived based on this, and then the characteristic curve information of the real-time laser diode is measured to determine the deterioration of the laser diode based on the characteristic curve of the real-time laser diode. It is possible to determine the lifespan by accurately understanding the information, and it is possible to correct the bias current or driving current range according to the actual degree of deterioration.

Description

Optical transmitting apparatus and method for verifying and adjusting characteristics during operation}

The present invention relates to an optical transmitting device capable of checking and correcting characteristics during operation and an operating method thereof. In particular, in a situation where an optical transmitting and receiving device for optical communication transmits data at high speed, the present invention relates to identifying the eye pattern and confirming the optical output characteristics. It relates to an optical transmission device that can confirm and correct characteristics during operation and its operating method to increase the stability and reliability of optical communication by improving optical transmission performance and predicting lifespan by comparing deterioration characteristics identified during production. .

Passive optical network (PON) technology is used to construct a high-speed subscriber network, and includes Ethernet PON (EPON) according to IEEE (Institute of Electrical and Electronics Engineers) 802.3av/ah, 10Gigabit EPON (10G-EPON), and International Telecommunication (ITUT). Representative examples include GPON (Gigabit PON) according to Union-Telecommunication Standardization Sector (G.984/7), XGSPON (10Gigabit PON), and NGPON2 (Next Generation PON) according to G.989.

In this way, through the PON configuration, the national office and the national office and the national office and the subscriber terminal are connected, but in the case of high-speed optical communication networks at the tens of Gbps level, 20km is considered the limit for stable operation. However, the quality of communication gradually decreases due to the deterioration of the laser diode in the transmitter due to use, so the practically stable use distance decreases over time.

Recently, in addition to being used for data networks such as Internet or intranet networks, PON is also used to transmit large amounts of wireless signals at high speed between a base station (AAU: Active Antenna Unit) and a control station (CU: Control/Central Unit) for mobile communication. It is also used for various IoT services and forms the basis of the information and communication society, so it is sensitive to failures and it is important to check the usage reliability period according to life expectancy. However, the technology currently used has difficulty in determining the degree of performance degradation of the optical communication device laser diode in real time, and there is a large deviation in life prediction accuracy, making it difficult to increase the reliability of the optical communication device.

The optical transmitter applied to the optical communication device that makes up the PON controls the laser diode according to the signal to be transmitted, thereby adjusting the size of the optical output differently depending on the signal. Usually, the optical transmitter can be distinguished by adding or reducing a certain amount of current based on the bias current. The optical output of the deviation corresponds to a different signal.

Therefore, the laser diode must be controlled so that the range of change in optical output increases according to the range of change in the constant control current. Since the optical output characteristics of each laser diode are different depending on the current for each device, taking this into consideration, adjust the optical output according to the current as much as possible. Select and operate an area where characteristic changes are linear.

In the operating characteristic curve of a laser diode, a region in which the output according to current changes is linear is selected, then the middle position is selected as the bias current, and the control current change width can be determined by considering the current change width in the linear area. For example, when operating in the NRZ (Non-Return to Zero) method, based on a bias current of 30mA, a current of 10mA is supplied to the laser diode at signal '0', and the supply current is increased to 50mA at signal '1' to increase the supply current to 50mA. can operate. In this case, the laser diode is operated with a current of ±20mA based on a bias current of 30mA.

Laser driving in this manner has the problem that the laser diode deteriorates over time, which causes the laser current response characteristic curve to change, distorting the optical output characteristics due to changes in control current. The solution to this problem so far is to simply measure the optical output power value and, if it is below expectations, change the setting position of the bias current (the axis position of the characteristic curve graph, meaning the size of the value) to artificially adjust the optical output size. It was a way to make it bigger.

This conventional bias current correction method only changes the position (size) of the bias current, and the range of the driving current increased or decreased based on the bias current is the same. Therefore, due to the non-linear output characteristics of the laser diode, the optical output eye mask and extinction ratio are changed. There is a limit to the low degree of correction for key characteristic values.

Furthermore, because it is difficult to measure the device characteristics and deterioration level of such a laser diode during operation, it is very difficult to predict the lifespan through measurement. Due to this problem, it is difficult to determine whether a failure has occurred due to the deterioration of the laser diode when a failure occurs during operation, and when a failure occurs due to the deterioration of the laser diode during operation, the response burden and cost increase.

In addition, optical transmission devices transmit signals at extremely high speeds of several Gbps to tens of Gbps, and due to the irregular pattern of such transmission signals, it is difficult to determine the exact deterioration state of the laser diode during operation of the optical communication device, and the current characteristics are difficult to determine. It is more difficult to confirm changes in curve information or characteristic curve information.

Therefore, the method of compensating the signal by collecting changes in the optical output of the laser diode and changing the bias current value using simple statistical values has limitations in compensating for the deterioration of the laser diode or predicting its lifespan.

Korean Patent Publication No. 10-2014-0117972 [Title of invention: Driving device for laser diode for optical communication] Korean Patent Publication No. 10-2015-0054530 [Title of invention: Laser driver for automatic bias and modulation control]

The purpose of the present invention to solve the above problems is to configure a monitoring optical receiver to monitor the output of the laser diode in the optical transmitter, and to continuously collect and use output characteristic curve information according to the driving current of the laser diode during the acceleration test. After identifying the deterioration characteristics, a multidimensional function for calculating characteristic curves over time is calculated, and the configuration parameter information of the multidimensional function is recorded as deterioration information in the control unit of the optical transmitter. In addition, if the predicted lifespan according to the deterioration characteristics is below the standard, it is defective. The control unit of the optical transmitter whose predicted lifespan is above the standard calculates the characteristic curve change over time using the deterioration information previously stored during operation, calculates the bias current value for driving the laser diode, and determines the laser diode based on the bias current. To provide an optical transmission device and an operating method capable of checking and correcting characteristics during operation by calculating the minimum and maximum current values to drive each and correcting driving conditions.

Another object of the present invention is to select a measurement pattern by distinguishing the pattern of the signal to be transmitted by the control unit during operation of the optical transmitter, and to divide the driving current range by increasing or decreasing the current at the next signal change point after transmitting the signal of the measurement pattern. The process of measuring the optical output of a laser diode when it becomes one of a plurality of measured current values is to identify all measured current values for the driving current range, combine and configure an eye pattern, and then determine the currently driven laser diode based on this. By deriving the optical output characteristic curve for the current range, some of the accurate characteristic curves of the real-time laser diode are actually measured, and based on this, the prediction accuracy for degradation is verified by comparing it with the characteristic curve according to pre-stored degradation information, and the laser diode The aim is to provide an optical transmission device and its operating method that can more accurately predict its lifespan.

An optical transmission device capable of checking and correcting characteristics during operation according to an embodiment of the present invention is an optical transmission device that provides an optical signal by controlling the optical output according to a digital transmission signal, and has a unique effect on the optical output according to the driving current. A laser diode having a characteristic curve of, a driving part that provides a driving current in a preset range to the laser diode, a monitoring part that measures the intensity of the output light of the laser diode through a monitoring photodiode, a transimpedance amplifier, and an analog-to-digital converter, It controls the driving unit according to the transmission signal and includes a control unit that corrects bias current and driving current settings for driving the laser diode, and the control unit controls the laser diode according to the time stored as the result of an acceleration test performed during the manufacturing process of the optical transmission device. It has expected deterioration characteristic information regarding deterioration, and generates expected characteristic curve information of the current laser diode through the cumulative usage time of the optical transmission device measured through a provided timer and the expected deterioration characteristic information stored in the deterioration characteristic storage unit. And, based on this, it includes a deterioration compensation unit that corrects the bias current and driving current settings for driving the laser diode.

As an example, the control unit distinguishes a measurement pattern that changes to a different signal after repeating a plurality of identical signals among the transmission signals, divides the last signal change direction of the measurement pattern into rising and falling driving current, and changes the signal to change the corresponding signal. The process of measuring the laser diode optical output when the changing driving current becomes one of a plurality of measured current values that divide the driving current range into unit current values is performed for all measured current values, such that the rise and fall It may further include a status checker that collects all the optical output measurement values of the laser diode for each measured current value and calculates real-time characteristic curve information of the laser diode for the current driving current setting range of the laser diode, and the deterioration compensation unit may include The expected characteristic curve information of the laser diode generated through the expected deterioration characteristic information is verified with the real-time characteristic curve information of the laser diode calculated through the status confirmation unit, and if it matches within the set range, the bias current and driving current are calculated based on the expected characteristic curve information. Settings can be corrected.

As an example, if the expected characteristic curve information and the characteristic curve information of the real-time laser diode do not match within the set range, the degradation compensation unit changes the accumulated usage time and makes the expected characteristic curve information match the characteristic curve information of the real-time laser diode within the preset range. After adjusting it to do so, the bias current and driving current settings can be corrected based on the adjusted expected characteristic curve information obtained as a result.

As an example, the deterioration compensation unit may calculate the predicted lifespan of the laser diode based on the accumulated usage time and actual accumulated usage time corresponding to the adjusted expected characteristic curve information, and generate alarm information including the predicted lifespan information.

As an example, the status confirmation unit measures the laser diode optical output measurement value for each rising and falling measurement current value for each measurement pattern, and all of the plurality of measurement current values that divide the driving current range that changes for signal change are measured. It may be sequential collection.

As an example, the status check unit includes a transmission signal pattern selection unit that distinguishes a measurement pattern that changes to a different signal after repeating a plurality of identical signals among transmission signals, and a driving current that determines the last signal change direction of the measurement pattern selected in the transmission signal pattern selection unit. It is divided into rising and falling, and the laser diode optical output is measured when the driving current that changes to change the signal becomes one of the plurality of measurement current values that divide the driving current range into unit current values. An output confirmation unit that sequentially collects all of the plurality of measured current values that divide the driving current range that changes to It may include an eye mask generator that configures the eye pattern, and a characteristic curve converter that calculates characteristic curve information of the real-time laser diode based on the eye pattern of the eye mask generator.

As an example, the deterioration compensation unit includes a deterioration characteristic storage unit that stores expected deterioration characteristic information about laser diode deterioration over time stored as results of an acceleration test performed during the manufacturing process of the optical transmitting device, and a deterioration characteristics storage unit that stores information on the expected deterioration characteristics of the laser diode deterioration over time, and the accumulated usage time of the optical transmitting device and the deterioration The expected characteristic curve information of the current laser diode is generated through the expected deterioration characteristic information stored in the characteristic storage unit, and the difference is calculated by comparing the expected characteristic curve information with the real-time characteristic curve information of the laser diode calculated through the status check unit. Whether bias correction is necessary is determined using at least one of the deterioration state confirmation unit that generates deterioration deviation information, the expected characteristic curve information of the current laser diode generated by the deterioration state confirmation unit, the characteristic curve information of the real-time laser diode, and the deterioration deviation information. It includes a deterioration compensation determination unit that determines the deterioration compensation, and a bias correction unit that corrects the bias current and drive current settings for driving the laser diode when the determination result of the deterioration compensation determination unit meets the criteria for bias correction, and the deterioration status confirmation unit determines the current laser diode. If the characteristic curve information of the real-time laser diode deviates more than a preset standard in a direction in which the characteristic curve information of the real-time laser diode deteriorates more than the expected characteristic curve information, the predicted lifespan can be calculated and alarm information containing the predicted lifespan information can be generated.

A method of operating an optical transmitting device capable of checking and correcting characteristics during operation according to another embodiment of the present invention is a method of operating an optical transmitting unit configured with a monitoring optical receiving unit for monitoring the output of a laser diode, wherein acceleration test equipment is preset. In an acceleration experiment environment, the laser diode of the optical transmitter is driven by current and the measured value of the monitoring optical receiver is received to continuously collect the output characteristic curve information of the laser diode, and the output characteristic curve information of the laser diode collected after the acceleration experiment is collected. Based on this, a deterioration information prediction step of identifying deterioration characteristics according to usage time, generating a multidimensional function for calculating a characteristic curve over time, and recording the configuration parameter information of the multidimensional function as expected deterioration characteristic information in the control unit of the optical transmitter; Depending on the operating time of the transmitter, the control unit of the optical transmitter calculates the expected characteristic curve information of the current laser diode based on the recorded expected deterioration characteristic information, and determines the minimum and maximum current values to drive the laser diode based on the bias current value. It includes an operation step of calculating and correcting the driving conditions of the laser diode. In the operation step, the control unit of the optical transmitter collects the output status information of the laser diode through the monitoring optical receiver, verifies the expected characteristic curve information, and calculates the expected characteristic curve. It may include correcting the driving conditions of the laser diode using at least one of information and collected output state information of the laser diode.

As an example, in the operation step, the control unit of the optical transmitter distinguishes a measurement pattern that changes to a different signal after repeating a plurality of identical signals among the transmission signals transmitted through the optical transmitter, and changes the last signal change direction of the measurement pattern to increase the driving current. In addition to dividing it into high and low, the laser diode optical output is measured with a monitoring optical receiver when the driving current that changes for the corresponding signal change becomes one of a plurality of measurement current values that divide the driving current range into unit current values. The output characteristic collection step is performed for all measured current values for the driving current range, and the control unit of the optical transmitter collects all optical output measurement values of the laser diode for each rising and falling measured current value, and then based on this, It includes a correction information calculation step of correcting the bias current value and driving current range for driving the laser diode, and calculating the minimum and maximum current values to drive the laser diode based on the bias current value, respectively. The eye pattern is constructed by combining the laser diode optical output measurement values for the rising and falling measured current values collected in the output characteristic collection stage, and then based on this, real-time laser diode characteristic curve information for the laser diode current is derived. You can.

Meanwhile, the correction information calculation step generates expected characteristic curve information of the current laser diode through the cumulative usage time and expected deterioration characteristic information of the optical transmission device, and deterioration deviation is calculated by comparing the expected characteristic curve information with the characteristic curve information of the real-time laser diode. generates information, determines whether bias correction is necessary using at least one of the generated expected characteristic curve information of the current laser diode, characteristic curve information of the real-time laser diode, and deterioration deviation information, and if it meets the criteria for bias correction, laser The bias current and drive current settings for driving the diode can be corrected.

In addition, the correction information calculation step calculates the predicted lifespan when a deviation exceeds a preset standard occurs in a direction in which the characteristic curve information of the real-time laser diode deteriorates more than the expected characteristic curve information of the current laser diode, and generates alarm information containing the predicted lifespan information. can be created.

An optical transmitting device capable of checking and correcting characteristics during operation according to an embodiment of the present invention and its operating method include identifying deterioration characteristics according to usage time through an acceleration test on the optical transmitter and recording the deterioration information in the control unit of the optical transmitter. In addition, by using the degradation information previously stored during the operation of the optical transmitter, the characteristic curve change over time is calculated to determine the bias current value for driving the laser diode and the minimum and maximum current values to drive the laser diode based on the bias current. After each calculation, the driving conditions are corrected to enable stable operation through appropriate compensation during the expected life time. In addition, the driving current value is corrected by reflecting the complex slope of the characteristic curve to improve performance and reliability. It has the effect of allowing you to do so.

In addition, the present invention selects a measurement pattern by distinguishing the pattern of the transmission signal during operation of the optical transmitter, and after transmitting the signal of the measurement pattern, a plurality of measurements are made by dividing the driving current range by increasing or decreasing the current at the next signal change point. The process of measuring the laser diode optical output when one of the current values is determined is to identify all measured current values in the driving current range, construct an eye pattern, and then based on this, create an optical output characteristic curve for the laser diode current. By deriving and measuring the characteristic curve information of the real-time laser diode, the expected characteristic curve according to the pre-stored deterioration information is verified using the characteristic curve of the real-time laser diode. If the expected and actual values are different, the expected characteristic curve is converted into the characteristic curve of the real-time laser diode. By adjusting based on , it is possible to perform bias correction based on the current characteristic curve of the accurate laser diode, and has the effect of predicting the life of the laser diode more accurately.

Figure 1 is a diagram showing the configuration of a typical passive optical network.
Figure 2 is a conceptual diagram showing the configuration of an optical transmitter capable of monitoring the laser diode output of the optical transmitter.
Figure 3 is a conceptual diagram showing the deterioration pattern of the optical transmitter laser diode according to usage time.
Figure 4 is a conceptual diagram showing the optical output for each driving current and the eye pattern of the optical output accordingly to explain the driving method of the laser diode of the optical transmitter.
Figure 5 is a conceptual diagram for explaining the change in optical output due to deterioration of the laser diode of the optical transmitter.
Figure 6 is a conceptual diagram of bias current and driving current correction of the laser diode of the optical transmitter.
Figure 7 is a conceptual diagram to explain the limitations of the bias correction method of the laser diode of the optical transmitter.
Figure 8 is a conceptual diagram illustrating a method of generating deterioration prediction information according to an acceleration experiment of an optical transmitter according to an embodiment of the present invention.
Figure 9 is a configuration diagram showing the configuration of an optical transmitter according to an embodiment of the present invention.
Figure 10 is a configuration diagram showing the configuration of a status confirmation unit according to an embodiment of the present invention.
Figure 11 is a configuration diagram showing the configuration of a deterioration compensation unit according to an embodiment of the present invention.
12 is a conceptual diagram illustrating an operation method for calculating a real-time laser diode eye pattern according to an embodiment of the present invention.
13 is an exemplary view of an eye pattern obtained according to an embodiment of the present invention.
Figure 14 is a flowchart showing the operation process of an optical transmitter capable of checking and correcting characteristics during operation according to an embodiment of the present invention.

It should be noted that the technical terms used in the present invention are only used to describe specific embodiments and are not intended to limit the present invention. In addition, the technical terms used in the present invention, unless specifically defined in a different sense in the present invention, should be interpreted as meanings generally understood by those skilled in the art to which the present invention pertains, and should not be overly comprehensive. It should not be interpreted as meaningless or in an excessively reduced sense. Additionally, if the technical terms used in the present invention are incorrect technical terms that do not accurately express the idea of the present invention, they should be replaced with technical terms that can be correctly understood by those skilled in the art. In addition, general terms used in the present invention should be interpreted according to the definition in the dictionary or according to the context, and should not be interpreted in an excessively reduced sense.

Additionally, as used in the present invention, singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as “consists of” or “comprises” should not be construed as necessarily including all of the various components or steps described in the invention, and some of the components or steps may not be included. It should be interpreted that it may or may further include additional components or steps.

Additionally, terms containing ordinal numbers, such as first, second, etc., used in the present invention may be used to describe constituent elements, but the constituent elements should not be limited by the terms. Terms are used only to distinguish one component from another. For example, a first component may be named a second component without departing from the scope of the present invention, and similarly, the second component may also be named a first component.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. However, identical or similar components will be assigned the same reference numbers regardless of the reference numerals, and duplicate descriptions thereof will be omitted.

Additionally, when describing the present invention, if it is determined that a detailed description of related known technologies may obscure the gist of the present invention, the detailed description will be omitted. In addition, it should be noted that the attached drawings are only intended to facilitate easy understanding of the spirit of the present invention, and should not be construed as limiting the spirit of the present invention by the attached drawings.

In particular, as an embodiment of the present invention, the laser diode refers to a laser diode used as the output of an optical transmission device, and even if there is no separate measurement value, 'optical output' refers to the laser diode of the optical transmission device by a specific driving current. It refers to the measurement value of the intensity of light output when operating.

Furthermore, even though it is referred to as bias current, driving current, etc. when explaining the operation of a laser diode, the term 'current' used here is understood to mean the size or value of the current provided to make the laser diode emit light, not the general term for electrical flow. The expression of changing the ‘position of the current’ should be understood as changing the ‘magnitude of the current value’.

Figure 1 shows the configuration of a typical passive optical network (PON). Looking at the configuration of this PON, it basically consists of one Optical Line Terminal (OLT) installed in a telephone office and an Optical Network Terminal (ONT) or ONU (ONU) of multiple subscribers. The Optical Network Unit has a point to multipoint network structure through an optical splitter (Remote Node), which is a passive optical branch device.

As shown, the OLT (1) equipped with an optical transceiver (1a) that converts electrical signals and optical signals to each other is connected to a plurality of subscriber ONTs (2) through an optical splitter (RN), and each ONT (2) Each optical transceiver 2a is configured. Through this configuration, high-speed communication services can be provided to a plurality of subscriber ONTs (2).

Such an optical transceiver internally includes an optical transmitter and an optical receiver. In order to provide an optical signal corresponding to a high-speed signal, the optical transmitter includes a laser diode that outputs an optical signal of a set wavelength. Since the laser diode of the optical transmitter is a key means of converting and outputting signals into physical light, its output quality must be maintained. To this end, a configuration for monitoring the output of the laser diode is applied inside the optical transmitter. It is common.

Figure 2 is a conceptual diagram showing the configuration of an optical transmitter capable of monitoring the laser diode output of the optical transmitter. As shown, the optical transmitter 10 generates an optical output of a set wavelength according to the applied current and transmits it through the optical path 20. A laser diode 13 transmits to the light receiving unit 30 of the corresponding equipment, a driver 12 that provides operating current for each signal to the laser diode 13, and receives information about the signal to be transmitted and operates according to the signal. It includes a control unit 11 that controls the driver 12 so that the laser diode 13 provides optical output corresponding to the signal. Furthermore, in order to monitor the output of the corresponding laser diode 13, the monitoring photodiode 14 receives a part of the output optical signal of the laser diode 13, and the monitoring photodiode 13 outputs output according to the received optical signal. A transimpedance amplifier (TIA) 15 that converts and amplifies the current into voltage and an analog-to-digital converter 16 that converts the output of the transimpedance amplifier 15 into a digital value and provides it to the control unit 11 are connected to a monitoring unit ( 14, 15, 16).

The control unit 11, which has received the output intensity information of the laser diode 13 measured according to the corresponding monitoring unit, determines the operating state of the laser diode 13 and then adjusts the laser diode operating current range of the driving unit 12 as necessary. The output quality of the laser diode is improved by adjusting, and if the measurement information of the monitoring unit is below the standard and cannot be overcome by output correction, failure occurrence information is generated to cause failure in equipment (not shown) to which the optical transmitter 10 is applied. A signal can be provided.

In reality, the laser diode 13 provides optical output that swings at high speed in response to the driving current that swings at high speed. Due to the nature of optical communication equipment, optical signals are continuously output, so its performance deteriorates as the cumulative use time increases. It deteriorates. In this way, not only does the output decrease as the laser diode deteriorates, but the current response characteristic curve of the laser diode changes due to deterioration, which also causes the optical output characteristics to be distorted due to changes in driving current.

That is, as time passes, the performance of the laser diode 13 gradually deteriorates, communication quality decreases, and the stable usable distance also decreases. If the output of the laser diode 13 falls below the standard within the predicted usage period, the laser diode 130 is determined to be defective.

Figure 3 is a conceptual diagram showing the deterioration pattern of the optical transmitter laser diode according to the usage time. As shown, if the range in which the output decreases according to the usage time does not meet the standard, it is considered defective. The output according to the usage time The level of degradation varies for each individual laser diode.

When the output characteristics of the laser diode change due to deterioration due to use, the driving current setting is changed to partially compensate for the deterioration state, but the correction efficiency is low because the exact deterioration state of the laser diode cannot be known during operation. .

Furthermore, if the output quality of the laser diode deteriorates beyond the standard range within the predicted usage period, it becomes difficult to respond to corrections and communication failures occur.

In the end, since the deterioration state of the laser diode due to use cannot be accurately determined during operation, there is a limit to improving communication quality through driving current compensation. If a failure occurs due to deterioration, not only is the burden of responding to the failure large, but it also leads to a decrease in service quality. Accordingly, there is a problem of lowered reliability.

Figure 4 is a conceptual diagram showing the optical output for each driving current and the eye pattern of the optical output accordingly to explain the driving method of the laser diode of the optical transmitter.

As shown, after identifying the output characteristic curve of a specific laser diode, a flat area among the corresponding output characteristic curves is selected, a bias current value (Ibias) is set as a standard for providing driving current, and the optical output size deviation according to the signal is determined. Determine the swing width of the driving current (minimum current (I0) and maximum current (I1)) so that it can be clearly recognized by the receiving side.

The corresponding driving current becomes I0 when the signal is '0', and when the signal is '1', the driving current increases to become I1. According to this driving current swing, the output of the laser diode swings alternately between P0 and P1. . When operating in the NRZ (Non-Return to Zero) method as shown, for example, based on a bias current of 30 mA, a current of 10 mA is supplied to the laser diode at signal '0', and a current of 10 mA is supplied to the laser diode at signal '1'. You can operate the laser diode by increasing it to 50mA. In this case, the laser diode is operated with a current of ±20mA based on a bias current of 30mA.

In this way, when the optical output according to signal '0' and the optical output according to signal '1' can be clearly distinguished by sufficient deviation between optical outputs, communication quality increases and long-distance communication becomes possible.

Meanwhile, the operating state according to the output characteristic curve of the laser diode is displayed as a waveform superimposed on one screen, and is called an eye pattern, through which communication quality can be checked. The larger the eye opening, which is the vertical and horizontal portion of the central part of the eye pattern, that is, the part where signals do not intersect, the signal strength is sufficient and the bit error rate is low.

As shown in the right waveform diagram, when the driving current range is appropriately set in the flat part of the output characteristic curve, it can be seen that the eye opening, which is the center of the eye pattern, is large and clean.

The operating range of the eye pattern and the output characteristic curve are related to each other, and the state of the output characteristic curve can be inversely estimated through the eye pattern.

Figure 5 is a conceptual diagram to explain the change in optical output due to deterioration of the laser diode of the optical transmitter. As shown, it can be seen that the output characteristic curve changes due to deterioration as the usage time of the laser diode increases, lowering the maximum output. .

If the output characteristic curve changes due to such deterioration due to use, the overall output may not decrease uniformly, but the output of the characteristic curve may decrease irregularly.

As shown, when the output characteristic curve changes due to deterioration, if the preset bias current (Ibias) and the upper and lower setting currents (I0, I1) for driving are maintained as shown, the optical output for signal '0' and Not only does the optical output for signal '1' decrease overall, but each deviation also becomes different, making it difficult for the receiving side to distinguish between signal '1' and signal '0'.

If the range of such deterioration is within a preset range, the deviation of optical output can be corrected to some extent by correcting the bias position for current control, thereby increasing the possibility of distinguishing optical output according to signal '0' and signal '1'. .

Figure 6 is a conceptual diagram of bias current and driving current correction of the laser diode of the optical transmitter. As shown, when the overall output is lowered as the output characteristic curve changes due to deterioration due to use of the laser diode, the preset bias as shown in Figure 5 If the current and the maximum and minimum driving currents are used as is, the amount of change in optical output according to the signal is distorted and communication quality is lowered. Therefore, the bias current value is changed as shown in FIG. 6 to correct the amount of change in optical output according to the signal to be balanced.

Most optical transmitters are configured to perform this bias correction function in order to compensate for the deterioration caused by the use of a laser diode. The current optical transmitter bias current correction method uses an absolute beam of the same size preset based on the bias current. The maximum current value and minimum current value are set as values.

For example, if a laser diode is operated with a current of ±20mA based on a bias current of 30mA, and the bias current is corrected to 40mA through compensation, the absolute upper and lower values of the driving current range remain the same (e.g., ±20mA).

As shown through this type of correction, even though the size ratio of the overall optical output is lowered, the optical output according to the signal is provided in a balanced manner, so reception performance can be maintained by amplifying the optical reception signal on the receiving side.

However, the deterioration state of the output characteristic curve as shown in FIG. 6 corresponds to an ideal situation in which the output decreases overall, and the change in the output characteristic curve due to actual deterioration changes irregularly as shown in FIG. 7.

Furthermore, in the case of a laser diode, even if it is a new product, its output characteristic curve is not uniform and is a non-linear multi-order function with many inflection points. Some linear sections of these output characteristic curves are selected and used as the driving current range, so they are not suitable for use. Accordingly, the output linear section of the deteriorated laser diode changes irregularly, making appropriate correction difficult when setting the bias current and setting the maximum and minimum current values of the same size based on this.

As shown in Figure 7, even if a new Ibias' is set by correcting the bias current, the slope of the upper output characteristic curve and the slope of the lower output characteristic curve are different based on the new bias current value, so the bias current If the maximum and minimum driving currents of the same size are set as a standard, the range of changes in optical output according to the signal becomes asymmetric and the quality of optical output deteriorates.

In this case, as the eye pattern shown on the right shows, the eye opening is reduced and distorted, resulting in lower reception quality. In other words, the existing bias current correction method has a limitation in that the degree of correction for key characteristics such as eye pattern and extinction ratio is low due to the non-linear output characteristics of the laser diode.

To solve this problem, after identifying the state of the output characteristic curve due to laser diode deterioration, select a linear section to determine the bias current value that becomes the standard for the driving current, and determine the appropriate maximum value to provide uniform optical output according to the signal. You can set the current value and minimum current value, but in reality, it is difficult to accurately determine the optical output characteristic curve of a laser diode in operating condition.

In other words, since the optical transmitter is continuously transmitting random signals at a speed of several to tens of Gbps during operation, the degree of decrease in optical power can be statistically measured by measuring the approximate average optical power, but the exact optical output in operating condition can be measured. Since the characteristic curve cannot be measured, the bias current and maximum and minimum currents can only be corrected according to a preset algorithm, and in this case, the efficiency of bias current correction due to deterioration is bound to be limited.

The present invention identifies the deterioration state caused by the use of such a laser diode during operation, checks for defects or failures, and estimates the output characteristic curve of the laser diode during operation to perform efficient bias current correction (resetting the driving current range). do.

To this end, the present invention measures the output characteristic curve of an individual laser diode and determines the change pattern due to deterioration, generates expected deterioration characteristic information to estimate the output characteristic curve over time, and stores this in the control unit of the optical transmitter. , the state of the output characteristic curve of the laser diode according to time during operation of the optical transmitter is estimated based on the stored expected deterioration characteristic information, and then bias current correction is performed accordingly, and the output characteristics of the laser diode are actually measured even in operating situations. After determining this, perform bias current correction based on this or verify the output characteristic curve of the laser diode estimated based on the previously stored expected deterioration characteristic information.

Figure 8 is a conceptual diagram illustrating a method of generating deterioration prediction information according to an acceleration experiment of an optical transmitter according to an embodiment of the present invention. This accelerated experiment is performed as a life acceleration test to ensure mass production quality during production.

The acceleration experiment for the optical transmitter 100 is to check optical output characteristic curve information for individual laser diodes and trend information according to deterioration, and is performed on each optical transmitter 100 that has been manufactured.

The acceleration test equipment 220 accelerates the usage time by operating it in a high temperature (e.g., 85°C) environment for tens of hours (e.g., 72 hours) in order to accelerate deterioration due to use, thereby showing the trend of performance deterioration according to use time. To be able to understand.

The illustrated optical transmitter 100 is equipped with a monitoring optical receiver (monitoring photo diode, transimpedance amplifier, analog-to-digital converter) to monitor the output of the laser diode, and operates the laser diode driver according to the settings of the control unit to generate the laser diode. It is possible to provide a driving current to the laser diode and measure the optical output intensity of the laser diode through the monitoring optical receiver.

The illustrated acceleration test equipment 220 includes a test setting unit 220 that sets the chamber temperature of the acceleration test equipment 220 and manages the test time based on setting information about the test temperature and time, and a test setting unit 220 that manages the test time and the inside of the chamber during the acceleration test. It includes an acceleration test control unit 210 that causes the optical transmitter 100 to operate with a test signal and periodically measures the output intensity of the laser diode for each driving current.

The acceleration test control unit 210 drives the laser diode of the optical transmitter 100 for each current in a preset acceleration experiment environment, receives the measured value of the monitoring optical receiver, and continuously collects the output characteristic curve information of the laser diode, Based on the output characteristic curve information of the laser diode collected after the acceleration experiment, the deterioration characteristics according to the usage time are identified, a multidimensional function for calculating the characteristic curve according to time is generated, and the configuration parameter information of the multidimensional function is transmitted to the control unit of the optical transmitter. Record the expected deterioration characteristic information.

As shown in the example on the right, during the acceleration test, the acceleration test control unit 210 increases the driving current of the laser diode with a sufficient measurement time to the control unit of the optical transmitter 100 under test and measures the optical output size for each size of the driving current. Repeat the recording (collecting output characteristic curve information) process.

During accelerated testing, laser diodes deteriorate quickly due to high temperatures. When output characteristic curves are accumulated and collected during an accelerated test for several tens of hours (e.g., 72 hours, 84 hours, etc.), the deterioration trend can be determined through changes in the corresponding output characteristic curves. becomes possible to predict.

Meanwhile, as shown in the example shown during such an acceleration test, it can be seen that the output characteristic curve, such as the initial a, deteriorates like b or c during the acceleration test. In this case, the expected lifespan can be determined by predicting the deterioration trend. In case of rapid deterioration as shown in c, the expected lifespan falls below the standard and may be judged as defective and discarded.

In this way, despite the fact that all optical transmitters 100 produced are forcibly deteriorated through accelerated testing, the lifespan reduction due to such deterioration is about 1/10 of the total expected lifespan, so sufficient lifespan (if not defective) is maintained. It can be provided, and the loss is only insignificant compared to the cost of responding to failures or the risk of service quality decline due to excessive deterioration during use.

In other words, life prediction and early detection of defects are important, and the deterioration state over time can be predicted according to the deterioration trend, which can be expressed as a multi-order function with one or more inflection points.

A multi-order function (curve function according to change) representing the expected characteristic curve over time can be generated and the parameters constituting the multi-order function can be extracted. The acceleration test control unit 210 of the acceleration test equipment 200 Parameter information of the multi-order function is recorded in the control unit (equipped with a storage memory) of the optical transmitter 100 as expected deterioration characteristic information. The multi-order function representing such an expected characteristic curve may be an approximate function obtained through various statistical methods, and the parameter information may be coefficient information or setting information of a function that estimates the output characteristic curve deteriorated over time.

When such parameter information is stored as expected deterioration characteristic information in the control unit of the optical transmitter 100, the optical transmitter 100 stores the accumulated operating time (the control unit uses a timer) based on the expected deterioration characteristic information stored periodically or at necessary points during operation. It is possible to determine the change state of the output characteristic curve due to deterioration by estimating the expected characteristic curve information according to the accumulated usage time (stored with accumulated usage time), and if the change in the corresponding output characteristic curve is greater than the standard, it is based on the predicted expected characteristic curve information. The deteriorated output characteristics can be improved more precisely through a correction procedure in which the bias current value is selected and the minimum and maximum drive current values are respectively set based on the predicted characteristic curve information.

However, this is generated by estimating the expected characteristic curve information according to the cumulative usage time based on the expected deterioration characteristic information set based on the deterioration trend according to the accelerated test, so the laser diode characteristic curve of the actual optical transmitter applied and operated in the equipment It may be different from

Therefore, based on the expected deterioration characteristic information, there is a need to verify the expected characteristic curve information according to the cumulative usage time through actual measurement of the laser diode characteristic curve at the relevant time.

FIGS. 9 to 13 are intended to explain a configuration for increasing accuracy by verifying the use of the expected deterioration characteristic information described in FIG. 8.

The present invention measures the output characteristics of a laser diode in operation with a set current driving range in real time, checks the accuracy and deviation of the expected characteristic curve information based on this, and adjusts the expected characteristic curve information or recalculates the predicted lifespan. It allows optimal response to deterioration caused by the use of laser diodes.

Figure 9 is a configuration diagram showing the configuration of the optical transmitter 100 according to an embodiment of the present invention, Figure 10 is a configuration diagram showing the configuration of the status check unit 111 according to an embodiment of the present invention, and Figure 11 is a configuration diagram showing the configuration of the optical transmitter 100 according to an embodiment of the present invention. This is a configuration diagram showing the configuration of the deterioration compensation unit 112 according to an embodiment of the invention. Furthermore, FIG. 12 is a conceptual diagram for explaining an operation method for calculating a real-time laser diode eye pattern according to an embodiment of the present invention, and FIG. 13 is an example diagram of an eye pattern obtained according to an embodiment of the present invention. The configuration and operation method of the present invention will be described with reference to FIGS. 9 to 13.

The optical transmitter 100 of the present invention is intended to provide an optical signal by controlling the optical output according to a digital transmission signal. As shown in FIG. 9, the optical transmitter 100 is a laser diode having a unique characteristic curve for optical output according to the driving current. (130), a driver 120 that provides a driving current in a preset range to the laser diode, a photodiode 140, a transimpedance amplifier 150, and an analog-to-digital converter 160 that monitor the intensity of the output light of the laser diode 130. ), and controls the driving unit 120 according to the transmission signal, measures and collects the optical output intensity of the laser diode 130 according to the change in driving current through the monitoring unit, and performs accelerated testing during the manufacturing process. It includes a control unit 110 that corrects the bias current and driving current settings for driving the laser diode 130 based on the degradation information recorded through and the collected optical output characteristics of the laser diode. The control unit 110 includes a timer for measuring the cumulative usage time of the optical transmission device and a storage unit or memory for recording it.

The output of the laser diode 130 of the optical transmitter 100 is transmitted to the optical receiver 30 of the communication target equipment through the optical path 20. If the quality of the optical output is good, the optical receiver 30 The received optical signal has an eye pattern with a wide and clear eye opening as shown on the right side of the configuration diagram.

The control unit 110, which stores the deterioration information obtained during the acceleration test process previously explained with reference to FIG. 8, determines the degree of change in the output characteristic curve of the laser diode that deteriorates with use time based on the stored deterioration information and predicts the current point in time. The driving current range can be reset by estimating the output characteristic curve and, if necessary, correcting the settings for the bias current value and minimum and maximum current values. However, estimation of the optical output characteristic curve based on the trend identified during limited acceleration testing is not possible. There may be differences from the output characteristic curve of the actual laser diode.

Therefore, there is a need to determine the output characteristics of laser diodes currently in operation.

In the past, only the approximate change in output characteristics was estimated by simply reducing the average output, but in the present invention, more accurate output characteristic information of the laser diode is determined.

To this end, the present invention introduces a new method of measuring the output intensity of the laser diode while the optical transmitter 100 is in operation.

In order to check the output characteristics during operation of the laser diode, the control unit 110 controls the driver 120 according to the transmission signal. Since the control unit 110 already knows the transmission signal, after repeating a plurality of the same signal among the transmission signals, another Measurement patterns that change into signals can be distinguished. The control unit 110 divides the last signal change direction of the corresponding measurement pattern into driving current rising and falling, and the driving current range that changes for the corresponding signal change will be one of a plurality of measured current values divided into unit current values. The process of measuring the optical output of the laser diode 130 is performed for all measured current values in the driving current range, and all of the optical output measured values of the laser diode for the rising and falling measured current values are collected. Use the method.

In fact, when the driver 120 provides a driving current to the laser diode 130, it does not suddenly supply the maximum or minimum drive current, but rather increases the current value from the minimum to the maximum drive current at high speed. The optical transmitter 100 is operated by changing the driving current for signals '1' and '0' by changing the driving current for signals '1' and '0' in a current value swing method that reduces the current value in the maximum driving current supply state or, conversely, reduces the current value to the minimum driving current. In this situation, a plurality of measured current values are set by dividing the swing range of the driving current into a unit current value (e.g., several mA units (e.g., 1 mA, 5 mA, etc.)), and the driving current according to each measured current value is measured by the laser diode 130. The optical output when provided can be measured through the monitoring unit, and by collecting them, an approximate eye pattern can be generated.

However, since the influence of the laser diode output on the previous driving state may remain, the measurement timing is based on a specific signal pattern of the same signal repetition in which the state of the laser diode is stabilized so that the state of the laser diode before measurement cannot affect the measurement. can be decided. For example, in the case of signal '11110', the output was sufficiently stabilized with multiple signals '1' and changed to signal '0', so when measuring the optical output of the laser diode according to the falling current at that point, noise (previously Measurement is possible without the influence of the output state of the laser diode. Conversely, in the case of signal '00001', the output increased to signal '1' while the output was sufficiently stabilized with multiple signals '0', so the current rising at that time The optical output of a laser diode can be measured without noise.

In this way, the optical output of the laser diode 130 is measured according to the driving current of the optical transmitter 100 during operation based on the preset measurement pattern (a pattern in which n identical signals are sequentially changed to another signal). If you go out, you can complete the eye pattern, and when the eye pattern is measured, you can check the output characteristic curve information for the driving range through it.

The operation method for calculating the real-time laser diode eye pattern according to an embodiment of the present invention will be examined in more detail through some examples in FIG. 12.

Looking at the example of FIG. 12, according to the output characteristic curve of the laser diode 130 shown in the lower left, the bias current value set for driving the laser diode 130 is 30 mA, the minimum driving current value is 10 mA, and the maximum driving current value is 10 mA. It can be seen that the current value is 50mA, and in this case, the size of the optical output of the laser diode 130 increases or decreases from P0 to P1 according to the current supplied to the driver, which swings at ±20mA based on 30mA.

That is, when the signal is '0', a current of 10 mA is supplied to the laser diode 130, and at this time, the optical output size of the laser diode 130 measured by the monitoring unit is P0, and when the signal is '1', a current of 50 mA is supplied. It is supplied to the laser diode 130, and at this time, the optical output size of the laser diode 130 measured by the monitoring unit is P1.

When the driver 120 changes the current supplied to the laser diode 130 from the state of signal '0' to the state of signal '1', the current of 10 mA is sequentially increased to 50 mA, and the driver 120 itself You can accurately know the current value of the changing driving current. Accordingly, the control unit 110 can measure the optical output of the laser diode 130 through the monitoring unit at a desired current value during the process of increasing or decreasing the driving current through the driver 120.

The control unit 110 can measure and collect the optical output of the laser diode 130 for each of a plurality of measured current values by dividing the driving current range into unit current values. When the unit current value is set to 5 mA as shown in the example, In the driving current range of 10mA to 50mA, the plurality of measured current values can be nine: 10mA, 15mA, 20mA, 25mA, 30mA, 35mA, 40mA, 45mA, and 50mA. Of course, the unit current value can be set smaller, in which case the number of measured current values can be increased.

Meanwhile, the optical output measurement according to each measured current value is measured separately when the current is rising and when the current is falling, and through this, an eye pattern as shown in the lower right corner can be formed. Accordingly, the optical output of the laser diode 130 for the driving current range is collected separately when the driving signal increases and when it decreases.

However, it is okay to measure the minimum and maximum current values only once.

Furthermore, as shown, the current value provided to the laser diode 130 is maintained at the lowest current value for a certain period of time in the measurement due to the increase in driving current so that noise due to the previous driving state of the laser diode 130 does not affect the measurement. Measurement can be performed only when the preset measurement pattern to be measured only when stabilized (in the case shown, when signal '0' becomes signal '1' after 4 or more consecutive occurrences) is confirmed. Likewise, measurement according to a drop in driving current can be performed only when a preset measurement pattern (as shown, when signal '1' becomes signal '0' after 4 or more consecutive occurrences) is confirmed.

In the illustrated example, the output of the laser diode 130 is measured (measured value A) when the measured current value is 10 mA, which corresponds to the lowest current value in the section where signal '0' is repeated four times, and the current after the corresponding measured pattern is measured. When is rising, measure the output of the laser diode (130) at 15 mA, which is the next measurement current value (measurement value B), and after confirming the measurement pattern in which signal '1' is repeated 4 times, when the measurement current value falling is 15 mA. Measure the output of the laser diode 130 (measured value G), and again measure the output of the laser diode 130 when the falling measurement current value is 20 mA after confirming the measurement pattern in which the signal '1' is repeated four times (measurement) You can measure the output at the point required to configure the eye pattern at the bottom right by using the value F). By collecting the optical output intensity of the laser diode 130 for all measured current values in the driving current range for both rising and falling currents, it is possible to form part of an eye pattern such as the bottom right shown, and this constructed eye pattern information By changing the phase and overlapping, it is possible to construct a practical eye pattern as shown in FIG. 13.

Once the eye pattern of the real-time laser diode 130 is configured in this way, an optical output characteristic curve for the current of the laser diode can be derived based on this. In other words, the characteristic curve information of the laser diode in real time can be obtained based on the eye pattern information, and the range of the driving current for generating the eye pattern is not the entire current range in which the laser diode 130 operates, but the driving current set for actual output. Since it is limited to the range (10mA~50mA), the real-time laser diode characteristic curve information obtained according to actual measurement becomes the limited laser diode characteristic curve information for the set driving current range.

Although only the output characteristic curve information of the laser diode for the currently set driving current range can be obtained, this allows the accurate state of the output characteristic curve of the laser diode in real time to be determined during operation. Based on this, the stored expected degradation characteristic information and cumulative use can be obtained. It is possible to verify the expected characteristic curve information of the laser diode generated by taking time into account.

The expected characteristic curve information obtained through the expected deterioration characteristic information and the accumulated usage time information of the laser diode 130 is information that predicts the overall output characteristic curve of the current laser diode 130, and is the optical output characteristic for the currently set driving current range. In addition, since the optical output characteristics for areas outside the driving current range are all predicted, expected characteristic curve information is required for driving current range correction (correction of bias current value, minimum and maximum current values) that requires changing the driving current range.

However, since this expected characteristic curve information is expected information obtained based on the deterioration trend obtained through accelerated testing, it may not match the current actual laser diode output characteristic curve, so the real-time laser diode characteristics derived based on the actual measurements described above Curve information can be used to verify expected characteristic curve information.

Through this verification, it can be confirmed whether the expected characteristic curve information can be used as is, whether the actual laser diode is more deteriorated than the expected characteristic curve information and has a shorter lifespan than predicted, or, conversely, whether the actual laser diode has deteriorated less.

Therefore, in order to more accurately predict the lifespan of the laser diode 130 or correct the driving current, the expected deterioration characteristic information is stored in the control unit 110 to calculate the expected characteristic curve information, and the characteristic curve of the laser diode in real time is calculated through actual measurements during operation. It is desirable to use all methods of deriving information.

Meanwhile, if the expected characteristic curve information and the characteristic curve information of the real-time laser diode do not match within the set range, the cumulative usage time is changed and the expected characteristic curve information is adjusted to match the characteristic curve information of the real-time laser diode within the preset range. Based on the resulting adjusted expected characteristic curve information, bias current and drive current settings can be corrected and predicted lifespan calculated.

Through this, the deviation in accumulated usage time between prediction and actual measurement can be confirmed, and bias correction can be performed precisely using the expected characteristic curve information for the entire driving current range, including characteristic curve information similar to the current actual measurement information. There will be.

As such, on the premise of using both methods, a more detailed configuration of the status check unit 111 and the deterioration compensation unit 112 of FIG. 9 will be described with reference to FIGS. 10 and 11.

10 is a diagram showing the configuration of the status check unit 111 according to an embodiment of the present invention. As shown, the status check unit 111 is for checking characteristics during operation and repeats a plurality of identical signals among the transmitted signals. A transmission signal pattern selection unit 111a that distinguishes measurement patterns (e.g., '00001', '11110') that are later changed to other signals, and a final signal change direction of the measurement pattern selected in the transmission signal pattern selection unit 111a. Divides the driving current into rising and falling, and monitors the optical output of the laser diode (130) when the driving current that changes to change the corresponding signal becomes one of a plurality of measured current values that divide the driving current range into a unit current value. An output confirmation unit 111b that measures through the units 140, 150, and 160 and sequentially collects all of the plurality of measured current values by dividing the driving current range that changes for signal change, and an output confirmation unit 111b. An eye mask generator 111c that configures an eye pattern by combining the optical output measurement values of the laser diode 130 for each measured current value collected for the driving current rise and fall through an eye pattern of the eye mask generator 111c. It includes a characteristic curve conversion unit 111d that calculates real-time characteristic curve information of the laser diode based on .

Through the status check unit 111, real-time characteristic curve information of the laser diode can be derived based on actual measurements, and driving current correction can be performed using the corresponding information. Of course, since it is insufficient to correct the driving current only with the information, the expected characteristic curve information of the current laser diode 130 is calculated through the expected deterioration characteristic information obtained through the post-production acceleration test, and then the real-time laser diode If it is verified with the characteristic curve information and matches, it is desirable to proceed with driving current correction using the expected characteristic curve information.

Figure 11 is a diagram showing the configuration of the deterioration compensation unit 112 according to an embodiment of the present invention. The deterioration compensation unit 112 is for compensating for deterioration due to the use of the laser diode 130, and is used in the optical transmission device. (including the optical transmitter) a deterioration characteristic storage unit 112a that stores expected deterioration characteristic information about laser diode deterioration over time stored as a result of an acceleration test performed during the manufacturing process, and stores the accumulated usage time and deterioration characteristics of the optical transmitter The expected characteristic curve information of the current laser diode 130 is generated through the expected deterioration characteristic information stored in the unit 112a, and the expected characteristic curve information and the real-time characteristic curve information of the laser diode derived through the status check unit 111 are generated. A deterioration state confirmation unit 112b that generates deterioration deviation information by comparing and calculating the difference, the expected characteristic curve information of the current laser diode generated by the deterioration state confirmation unit 112b, the characteristic curve information and deterioration of the real-time laser diode A deterioration compensation determination unit 112c that determines whether bias correction is necessary using at least one of the deviation information, and a bias current for driving a laser diode when the determination result of the deterioration compensation determination unit 112c satisfies the criteria for the need for bias correction, and It includes a bias correction unit 112d that corrects the driving current setting.

In this way, periodically or upon request, the control unit 110 determines the need for driving current correction (correction of bias current value, maximum and minimum current values) through the degradation compensation determination unit 112c of the degradation compensation unit 112, and predicts Based on the characteristic curve information, the characteristic curve information of the real-time laser diode, and the degradation deviation information, use one of these or reflect the degradation deviation information to recalculate the expected characteristic curve information (adjust the accumulated usage time so that the degradation deviation information is the smallest) ), you can correct the settings for the driving current.

Furthermore, the deterioration state check unit 112b calculates the predicted lifespan when a deviation exceeds a preset standard occurs in a direction in which the characteristic curve information of the real-time laser diode deteriorates more than the expected characteristic curve information of the current laser diode, and the predicted lifespan information is The included alarm information can be generated and transmitted to the control unit of the optical transmitting device interoperating with the control unit 110 or the target equipment to which the optical transmitting device is applied. The alarm information is ultimately delivered to the administrator to enable replacement before a failure occurs if the expected lifespan is shorter than the preset lifespan.

In this way, the deterioration state can be comprehensively identified, the driving current range as well as the overall output characteristic curve of the laser diode can be estimated, and the driving current setting can be corrected based on accurate characteristic information to maintain performance and expected lifespan. Correction is also possible, enabling stable service operation.

Figure 14 is a flowchart showing the operation process of an optical transmitter capable of checking and correcting characteristics during operation according to an embodiment of the present invention.

The optical transmitting unit includes a monitoring optical receiving unit for monitoring the output of the laser diode.

As a preliminary step for the operation of the optical transmitter to check and correct the output characteristic information of the laser diode during actual operation, it includes the step of continuously measuring the output of the laser diode during the life acceleration test.

The continuous output measurement step is to continuously collect the output characteristic curve information of the laser diode by receiving the measured value of the monitoring light receiver while driving the laser diode of the optical transmitter by current in a preset acceleration experiment environment through acceleration test equipment. Includes process.

Meanwhile, the acceleration test equipment determines that the optical transmitter under test is defective if the change in the characteristic curve due to the deterioration of the laser diode exceeds the standard during this process and the predicted lifespan falls below expectations.

As a second preliminary step, it includes generating prediction information on deterioration characteristics over time through life acceleration test results.

The step of generating this deterioration characteristic prediction information is to determine the deterioration characteristics according to the usage time based on the output characteristic curve information of the laser diode collected after the acceleration experiment, generate a multidimensional function for calculating the characteristic curve over time, and Configuration parameter information is generated as expected deterioration characteristic information.

Lastly, the preliminary step includes storing prediction information on deterioration characteristics over time in the optical transmitter under test. In practice, the expected deterioration characteristic information is recorded in the control unit of the optical transmitter equipped with a storage memory.

In order to check and correct the output characteristic information of the laser diode during actual operation of the optical transmitter in which the expected deterioration characteristic information is recorded as described above and the predicted lifespan is above the standard, the following steps are included.

It includes an actual measurement step of generating an eye pattern during operation of the optical transmitter and deriving information on the output characteristics of the laser diode based on this.

In this actual measurement step, the control unit of the optical transmitter distinguishes a measurement pattern that changes to a different signal after repeating a plurality of identical signals among the transmission signals transmitted through the optical transmitter, and determines the direction of the final signal change of the corresponding measurement pattern by driving current rising and falling. In addition to discriminating, the process of measuring the laser diode optical output with the monitoring light receiver when the driving current that changes to change the corresponding signal becomes one of a plurality of measurement current values that divide the driving current range into a unit current value. The output characteristic collection step is performed for all measured current values for the driving current range, and the control unit of the optical transmitter collects all the optical output measured values of the laser diode for each rising and falling measured current value and then combines them to create an eye pattern. It includes the step of configuring and then deriving real-time characteristic curve information of the laser diode for the current of the laser diode based on this.

In addition, it includes the step of calculating expected characteristic curve information using the stored degradation characteristic prediction information, and generates deterioration deviation information by comparing the characteristic curve information of the real-time laser diode with the expected characteristic curve information, and through this, the expected characteristic curve information and If the characteristic curve information of the real-time laser diode through actual measurement is inconsistent and the deterioration is more severe than expected, the step of re-predicting the lifespan and generating lifespan prediction information including the reduced lifespan as notification information may be further included.

For reference, the step of deriving the characteristic curve information of the real-time laser diode above and the step of calculating the expected characteristic curve information using the stored deterioration characteristic prediction information are based on the minimum and maximum current values to drive the laser diode based on the bias current value, respectively. After calculating each current value, a process of correcting the driving conditions of the laser diode can be performed, but preferably, the driving current of the laser diode is set by utilizing both the expected characteristic curve information and the real-time characteristic curve information of the laser diode through actual measurements. Correct (bias current value, maximum and minimum current value settings).

In other words, expected characteristic curve information of the current laser diode is generated through the cumulative usage time and expected deterioration characteristic information of the optical transmission device, and deterioration deviation information is generated by comparing the expected characteristic curve information with the characteristic curve information of the real-time laser diode obtained through actual measurement. Generates and determines whether bias correction is necessary using at least one of the generated expected characteristic curve information of the current laser diode, characteristic curve information of the real-time laser diode, and deterioration deviation information, and operates the laser diode if it meets the criteria for requiring bias correction. You can correct the bias current and drive current settings for .

On the other hand, if the expected characteristic curve information and the characteristic curve information of the real-time laser diode do not match within the set range (deterioration deviation information exceeds the standard range), the expected characteristic curve information changes to the characteristic curve information of the real-time laser diode while changing the accumulated usage time. After adjusting to match the preset range (deterioration deviation information matches the standard range), the bias current and driving current settings are corrected based on the adjusted expected characteristic curve information obtained as a result, and the actual laser diode based on the current state is adjusted to match. Lifespan can be predicted.

Furthermore, if the characteristic curve information of the real-time laser diode deteriorates more than the expected characteristic curve information of the current laser diode and there is a deviation beyond a preset standard, the predicted lifespan can be calculated and alarm information containing the predicted lifespan information can be generated. , the corresponding alarm information can be transmitted to the control unit of communication equipment equipped with an optical transmitter.

Anyone skilled in the art to which the present invention pertains can make modifications and changes to the above-described content without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but are for illustrative purposes, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of the present invention.

Furthermore, the optical transmission device may be implemented with hardware components, software components, and/or a combination of hardware components and software components.

Additionally, components described in the embodiments include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), and a programmable logic unit (PLU). It may be implemented using one or more general-purpose or special-purpose computers, such as a logic unit, microprocessor, or any other device capable of executing and responding to instructions.

Software may include a computer program, code, instructions, or a combination of one or more of these, and may independently or collectively instruct the delay detection device to operate as desired. can do.

The various devices and components described herein may be implemented by optical elements, sensing elements, hardware circuits (e.g., semiconductor-based logic circuits), firmware, software, or a combination thereof. For example, it can be implemented using transistors, logic gates, and electronic circuits in the form of various electrical structures, and lenses and filters in the form of optical structures.

100: Optical transmission unit 110: Control unit
111: Status confirmation unit 112: Deterioration compensation unit
120: driving unit 130: laser diode
140: Monitoring photo diode 150: Transimpedance amplifier
160: analog-to-digital converter 200: accelerated test equipment
210: Acceleration test control unit 220: Test setting unit

Claims (10)

An optical transmission device that provides optical signals by controlling optical output according to digital transmission signals,
A laser diode having a unique characteristic curve for optical output according to driving current;
a driver that provides a driving current to the laser diode in a preset range;
a monitoring unit that measures the intensity of output light from the laser diode through a monitoring photodiode, a transimpedance amplifier, and an analog-to-digital converter;
A control unit that controls the driving unit according to a transmission signal and corrects bias current and driving current settings for driving the laser diode,
The control unit has information on expected deterioration characteristics of the laser diode according to time stored as a result of an acceleration test performed during the manufacturing process of the optical transmission device, and includes the cumulative use time of the optical transmission device measured through a provided timer and the An operational characteristic that includes a deterioration compensation unit that generates expected characteristic curve information of the current laser diode through the expected deterioration characteristic information stored in the deterioration characteristic storage unit, and corrects the bias current and driving current settings for driving the laser diode based on this. An optical transmission device that can be checked and corrected.
The method of claim 1, wherein the control unit
Among the transmitted signals, a measurement pattern that changes to a different signal after multiple repetitions of the same signal is distinguished, the direction of change in the final signal of the measurement pattern is divided into driving current rise and fall, and the driving current that changes for the corresponding signal change is driven. The process of measuring the laser diode optical output when one of a plurality of measured current values that divide the current range into unit current values is performed for all measured current values, so that the measured current values for each rise and fall are measured. It further includes a status checker that collects all the optical output measurement values of the laser diode and calculates real-time characteristic curve information of the laser diode for the current driving current setting range of the laser diode,
The deterioration compensation unit verifies the expected characteristic curve information of the laser diode generated through the expected deterioration characteristic information with the characteristic curve information of the real-time laser diode calculated through the status check unit, and if it matches within a set range, provides the expected characteristic curve information. An optical transmission device capable of checking and correcting characteristics during operation, characterized by correcting the bias current and driving current settings as a standard.
The method according to claim 2, wherein when the expected characteristic curve information and the characteristic curve information of the real-time laser diode do not match within a set range, the degradation compensation unit changes the accumulated usage time and changes the expected characteristic curve information to the characteristic curve of the real-time laser diode. An optical transmission device capable of checking and correcting characteristics during operation, characterized in that the bias current and driving current settings are adjusted based on the adjusted expected characteristic curve information obtained as a result after adjusting the information to match the preset range.
The method according to claim 3, wherein the degradation compensation unit calculates the predicted lifespan of the laser diode based on the accumulated usage time and actual accumulated usage time corresponding to the adjusted expected characteristic curve information, and generates alarm information including the predicted lifespan information. An optical transmission device capable of checking and correcting characteristics during operation, which is characterized by generating.
The method according to claim 2, wherein the status checker measures the laser diode optical output measurement value for each rising and falling measurement current value one by one for each measurement pattern, and divides the driving current range that changes for the signal change into a plurality of devices. An optical transmission device capable of checking and correcting characteristics during operation, characterized by sequential collection of all measured current values.
The method of claim 2, wherein the status confirmation unit
a transmission signal pattern selection unit that distinguishes a measurement pattern that changes to a different signal after repeating a plurality of identical signals among transmission signals;
The final signal change direction of the measurement pattern selected by the transmission signal pattern selection unit is divided into driving current rising and falling, and the driving current changed for the corresponding signal change is a plurality of measurement currents in which the driving current range is divided into unit current values. an output confirmation unit that measures the laser diode optical output when it becomes one of the values and sequentially collects all of the plurality of measured current values divided by the driving current range that changes to change the signal;
an eye mask generator that configures an eye pattern by combining laser diode optical output measurement values for each measured current value collected for driving current rise and fall through the output confirmation unit;
An optical transmission device capable of checking and correcting characteristics during operation, comprising a characteristic curve conversion unit that calculates characteristic curve information of the laser diode in real time based on the eye pattern of the eye mask generator.
The method of claim 2, wherein the deterioration compensation unit
a deterioration characteristic storage unit that stores expected deterioration characteristic information about laser diode deterioration over time stored as a result of an acceleration test performed during the manufacturing process of the optical transmission device;
Generating expected characteristic curve information of the current laser diode through the cumulative usage time of the optical transmission device and expected deterioration characteristic information stored in the deterioration characteristic storage unit, and real-time laser diode calculated through the expected characteristic curve information and the status confirmation unit. A deterioration state confirmation unit that generates deterioration deviation information by comparing the characteristic curve information and calculating the difference;
a deterioration compensation determination unit that determines whether bias correction is necessary using at least one of the expected characteristic curve information of the current laser diode generated by the deterioration state confirmation unit, the characteristic curve information of the real-time laser diode, and the deterioration deviation information;
A bias correction unit that corrects the bias current and drive current settings for driving the laser diode when the determination result of the degradation compensation determination unit meets the criteria for bias correction,
The deterioration state confirmation unit calculates a predicted lifespan when a deviation exceeds a preset standard occurs in a direction in which the characteristic curve information of the real-time laser diode deteriorates more than the expected characteristic curve information of the current laser diode, and provides alarm information containing the predicted lifespan information. An optical transmission device capable of checking and correcting characteristics during operation, characterized in that it generates.
A method of operating an optical transmitter configured with a monitoring optical receiver for monitoring the output of a laser diode, comprising:
The acceleration test equipment continuously collects the output characteristic curve information of the laser diode by receiving the measured value of the monitoring light receiver while driving the laser diode of the optical transmitter by current in a preset acceleration experiment environment, and collects the information after the acceleration experiment. Based on the output characteristic curve information of the laser diode, the deterioration characteristics according to usage time are identified, a multidimensional function for calculating the characteristic curve over time is generated, and the configuration parameter information of the multidimensional function is transmitted to the control unit of the optical transmitter as expected deterioration characteristic information. A deterioration information prediction step of recording;
Depending on the operating time of the optical transmitter, the control unit of the optical transmitter calculates the expected characteristic curve information of the current laser diode based on the recorded expected deterioration characteristic information, and calculates the lowest current value to drive the laser diode based on the bias current value and Including an operation step of calculating the maximum current value and correcting the driving conditions of the laser diode,
In the operation step, the control unit of the optical transmitter collects output state information of the laser diode through the monitoring optical receiver to verify the expected characteristic curve information, and combines the expected characteristic curve information with the collected output state information of the laser diode. A method of operating an optical transmission device capable of checking and correcting characteristics during operation, including the step of correcting driving conditions of a laser diode using at least one of the following.
The method of claim 8, wherein the operation step is,
The control unit of the optical transmitter distinguishes a measurement pattern that changes to a different signal after repeating a plurality of identical signals among the transmission signals transmitted through the optical transmitter, and divides the final signal change direction of the measurement pattern into driving current rising and falling. In addition, the process of measuring the laser diode optical output with the monitoring light receiver when the driving current that changes to change the corresponding signal becomes one of a plurality of measured current values by dividing the driving current range into a unit current value is called driving current. an output characteristic collection step performed on all measured current values for the range;
The control unit of the optical transmitter collects all the optical output measurement values of the laser diode for the rising and falling measured current values, and then corrects the bias current value and driving current range for driving the laser diode based on this, wherein the bias It includes a correction information calculation step of calculating the minimum and maximum current values to drive the laser diode based on the current value, respectively,
The correction information calculation step configures an eye pattern by combining the laser diode optical output measurement values for the rising and falling measured current values collected in the output characteristic collection step, and then calculates the real-time laser diode current for the laser diode based on this. A method of operating an optical transmission device capable of checking and correcting characteristics during operation, characterized by deriving characteristic curve information.
The method of claim 9, wherein the correction information calculation step generates expected characteristic curve information of the current laser diode through the cumulative usage time of the optical transmission device and the expected deterioration characteristic information, and calculates the expected characteristic curve information and the real-time laser diode. Deterioration deviation information is generated by comparing characteristic curve information, and whether bias correction is necessary is determined using at least one of the generated expected characteristic curve information of the current laser diode, the characteristic curve information of the real-time laser diode, and the deterioration deviation information. A method of operating an optical transmission device capable of checking and correcting characteristics during operation, characterized in that the bias current and driving current settings for driving the laser diode are corrected when the bias correction requirement criteria are met.

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