CN116094591A - Optical module testing device and calibration method - Google Patents

Abstract

The invention provides an optical module testing device and a calibration method, wherein the testing device comprises a first photodiode PIN1, a second photodiode PIN2, a first transimpedance amplifier, a second transimpedance amplifier and a filter; the two photodiodes are used for receiving optical signals of the optical module to be tested, converting the optical signals into current signals and respectively outputting the current signals to the first transimpedance amplifier and the second transimpedance amplifier; the first transimpedance amplifier converts a current signal into a voltage signal and outputs the voltage signal to the filter; the filter outputs the filtered voltage signal to the peak value detection circuit; the peak detection circuit outputs a peak voltage to a calculation unit; the second transimpedance amplifier converts the current signal into a voltage signal and outputs the voltage signal to the calculation unit. The invention can simplify the production testing device and reduce the production cost on the premise of ensuring the testing precision.

Description

Optical module testing device and calibration method

Technical Field

The invention relates to the technical field of optical communication, in particular to an optical module testing device.

Background

The most important 2 parameters of the emitting end of the optical module are optical power and an optical eye diagram, and the optical power meter and the optical oscilloscope are used for testing and debugging respectively, so that the cost is high.

The debugging and testing of the TX end of the optical module mainly needs to debug the transmitted output optical power, and the extinction ratio parameter of the eye pattern, as shown in fig. 1, is conventionally implemented by using an error code meter to send a pseudo-random code modulation signal of a specified rate of the optical module to be tested, sending corresponding optical power by the optical module, respectively testing the optical power and the extinction ratio by an interface optical fiber to an optical power meter and an optical oscilloscope, and then changing bias current and mod current by adjusting an internal register of the optical module to approach the target optical power and the extinction ratio.

The current test value is fed back by continuously communicating with the optical power meter and the optical oscilloscope, the test value of the optical power meter and the optical oscilloscope is required to be read after the delay is refreshed again after the setting values of the IB and the IMOD in the optical module are changed once, and the debugging efficiency is low; meanwhile, the optical power meter and the optical oscilloscope are expensive instruments, and the cost is high under the condition of mass production, debugging and testing. Therefore, an instrument that can efficiently and accurately test the optical power and extinction ratio would be very important.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides an optical module testing device and a calibration method, which directly omit an optical power meter and an optical oscilloscope, greatly reduce the production cost, simplify the production testing device and reduce the production cost on the premise of ensuring the testing accuracy without losing the testing accuracy. The technical problem of high debugging and testing cost of the TX end of the conventional optical module is solved.

The aim of the invention is achieved by the following technical scheme:

an optical module testing device comprises a to-be-miscoded instrument, a testing board and an optical module to be tested; the optical module to be tested is arranged on the test board; the error code instrument is connected with the test board; the test board outputs the optical signal of the optical module to be tested to the test device;

the testing device comprises a first photodiode PIN1, a second photodiode PIN2, a first transimpedance amplifier TIA1, a second transimpedance amplifier TIA2 and a filter;

the first photodiode PIN1 receives an optical signal of the optical module to be detected, converts the optical signal into a current signal, and outputs the current signal to the first transimpedance amplifier TIA1;

the first transimpedance amplifier TIA1 converts a current signal into a voltage signal and outputs the voltage signal to the filter;

the filter outputs the filtered voltage signal to the peak value detection circuit;

the peak detection circuit outputs peak voltage adc1 to the MCU computing unit;

the second photodiode PIN2 receives an optical signal of the optical module to be detected, converts the optical signal into a current signal, and outputs the current signal to the second transimpedance amplifier TIA2;

the second transimpedance amplifier TIA2 converts the current signal into a voltage signal and outputs the voltage signal adc2 to the MCU computing unit;

the MCU computing unit performs processing operation to obtain a corresponding extinction ratio ER; the MCU computing unit can discharge the peak detection circuit.

Alternatively or preferably, the first transimpedance amplifier TIA1 is a high-speed transimpedance amplifier, and outputs a high-speed current change as a high-speed voltage change signal.

Alternatively or preferably, the second transimpedance amplifier TIA2 is a low-speed transimpedance amplifier, and amplifies an average voltage value of the output photocurrent, where the average voltage value corresponds to an average optical power Pavg of the optical signal.

Optionally or preferably, the filter is a two-stage low-pass filter, and is used for filtering out unwanted noise and overshoot so as to match the speed of the current optical module and keep the stable test of the level.

Alternatively or preferably, the first photodiode PIN1 and the second photodiode PIN2 are PIN photodiodes, and one end is loaded with a direct BIAS voltage BIAS, so that an optical signal can be converted into a current signal with high speed change.

Optionally or preferably, the optical fiber comprises an adjustable attenuator and an optical splitter; the adjustable attenuator is connected with the test board and the test device at the same time; the optical signals firstly enter the adjustable attenuator and then are output to a first photodiode PIN1 and a second photodiode PIN2 in the testing device after being split by the optical splitter.

Based on the technical scheme, the optical module testing device provided by the invention has the following technical effects:

(1) When the optical power and extinction ratio are tested, the optical power meter and optical oscilloscope resources are saved, and the production debugging and testing cost is greatly reduced;

(2) Compared with the existing testing device, the invention does not need to set delay waiting for data refreshing, improves the testing efficiency and does not lose accuracy.

The invention also provides a calibration method of the optical module testing device, which is based on the optical module testing device and comprises the following steps:

s1, transmitting an optical signal of an optical module to be tested into an adjustable attenuator, a standard optical power meter and a standard optical oscilloscope for simultaneous test; the optical signals entering the adjustable attenuator are respectively sent into a first photodiode PIN1 and a second photodiode PIN2 in the testing device through an optical branching device;

s2, recording the model of the current optical module to be tested, binding the calibration parameters with the model, and setting corresponding speed and code type parameters corresponding to the model by BERT;

s3, dividing the optical power range into N equal parts according to the accuracy required to be regulated, setting the optical power output value from Pavg_min to Pavg_max in a constant stepping way, respectively recording the adc2 amounts of a standard optical power meter and a testing device, and performing piecewise linear calibration;

s4, calibrating ER values, specifically comprising:

s41, fixing input optical power, and adjusting attenuation in real time through an adjustable attenuator to ensure constant optical power input into the testing device;

s42, changing parameters of the optical module, under the condition of ensuring constant optical power, setting the optical module from the minimum value to the maximum value of ER (ER), determining the step size according to the required test precision, recording the ER value of the standard optical oscilloscope and the adc1 amount of the test device, and performing piecewise linear calibration;

s43, storing the calibration coefficient into an MCU (micro control unit) computing unit of the testing device, and corresponding to the corresponding optical module model;

s5, removing the standard optical power meter and the standard optical oscilloscope.

The calibration method provided by the invention is simple to operate, the accuracy of the testing device can be ensured, and the testing device after calibration can be directly put into use.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a prior art test apparatus for optical power versus eye extinction ratio;

FIG. 2 is a schematic diagram of the structure of the present invention;

FIG. 3 is a schematic diagram of a testing apparatus according to the present invention;

FIG. 4 is a graph of the laser P-I in accordance with the present invention;

fig. 5 is a schematic diagram of the device connection at calibration in the present invention.

Detailed Description

It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1:

the optical module testing device provided by the embodiment comprises a to-be-miscode meter, a testing board and an optical module to be tested; the optical module to be tested is arranged on the test board; the error code instrument is connected with the test board; the test board outputs the optical signal of the optical module to be tested to the test device;

as shown in fig. 3, the testing device comprises a first photodiode PIN1, a second photodiode PIN2, a first transimpedance amplifier TIA1, a second transimpedance amplifier TIA2 and a filter;

the first photodiode PIN1 and the second photodiode PIN2 are both PIN type photodiodes, and are used for receiving optical signals of an optical module to be tested, one end of each of the first photodiode PIN1 and the second photodiode PIN2 is loaded with direct bias voltage-Vpd, and the optical signals can be converted into high-speed changing current signals to be converted into high-speed changing current signals, wherein the first photodiode PIN1 outputs the current signals to the first transimpedance amplifier TIA1; the second photodiode PIN2 outputs a current signal to the second transimpedance amplifier TIA2;

the first transimpedance amplifier TIA1 is a high-speed transimpedance amplifier, outputs high-speed current change to a high-speed voltage change signal, and outputs the voltage signal to the filter;

the filter is a two-stage low-pass filter, and the voltage signal passes through the filter to filter out unwanted noise and overshoot, match the speed of the current optical module and keep the stable test of the level;

the filter outputs the filtered voltage signal to the peak value detection circuit;

the peak detection circuit outputs peak voltage adc1 to the MCU computing unit;

the second transimpedance amplifier TIA2 is a low-speed transimpedance amplifier and amplifies an average voltage value of output photocurrent, and the voltage signal corresponds to average optical power Pavg; and outputting the voltage signal adc2 to the MCU computing unit;

the MCU computing unit performs processing operation to obtain a corresponding extinction ratio ER; the MCU computing unit can discharge the peak detection circuit.

As shown in fig. 2, the embodiment further comprises an adjustable attenuator; the adjustable attenuator is connected with the test board and the test device at the same time; the optical signal enters the adjustable attenuator and then enters the testing device.

The calculation principle of the extinction ratio ER in this embodiment is:

as shown in fig. 4, the P-I curve of the laser hardly emits light when the current of the laser is smaller than Ith, and emits light linearly with a fixed SE after exceeding Ith, but normally, IBIAS is slightly larger than Ith, and a certain amount of IMOD modulation current is added, and when imod=0, the optical power is P0, and is recorded as a 0 signal; after IMOD is added, the optical power is P1 and is recorded as a1 signal, and the output average optical power is pavg= (p0+p1)/2, and the extinction ratio er=10×1g (P1/P0); thus, as long as 2 parameters in P1, P0, ER and Pavg are known, another 2 parameters can be obtained; knowing P1 and Pavg, p0=2×pavg-P1 is known, while er=10×lg (P1/(2×pavg-P1)) is known.

The embodiment also provides a calibration method of the optical module testing device, which is based on the optical module testing device and specifically comprises the following steps:

s1, as shown in FIG. 5, sending an optical signal of an optical module to be tested into an adjustable attenuator, a standard optical power meter and a standard optical oscilloscope for testing simultaneously; the optical signals entering the adjustable attenuator are respectively sent into a first photodiode PIN1 and a second photodiode PIN2 in the testing device through an optical branching device; s2, recording the model of the current optical module to be tested, binding the calibration parameters with the model, and setting corresponding speed and code type parameters corresponding to the model by BERT;

s3, dividing the optical power range into N equal parts according to the accuracy required to be regulated, setting the optical power output value from Pavg_min to Pavg_max in a constant stepping way, respectively recording the adc2 amounts of a standard optical power meter and a testing device, and performing piecewise linear calibration;

s4, calibrating ER values, specifically comprising:

s41, fixing input optical power, and adjusting attenuation in real time through an adjustable attenuator to ensure constant optical power input into the testing device;

s42, changing parameters of the optical module, under the condition of ensuring constant optical power, setting the optical module from the minimum value to the maximum value of ER (ER), determining the step size according to the required test precision, recording the ER value of the standard optical oscilloscope and the adc1 amount of the test device, and performing piecewise linear calibration;

s43, storing the calibration coefficient into an MCU (micro control unit) computing unit of the testing device, and corresponding to the corresponding optical module model;

s5, removing the standard optical power meter and the standard optical oscilloscope.

The structures, functions, and connections disclosed herein may be implemented in other ways. For example, the embodiments described above are merely illustrative, and other mounting arrangements are possible, for example, multiple components may be combined or integrated with one another; in addition, each functional component in the embodiments herein may be integrated into one functional component, or each functional component may exist alone physically, or two or more functional components may be integrated into one functional component.

The foregoing is merely a preferred embodiment of the invention, and it is to be understood that the invention is not limited to the form disclosed herein but is not to be construed as excluding other embodiments, but is capable of numerous other combinations, modifications and environments and is capable of modifications within the scope of the inventive concept, either as taught or as a matter of routine skill or knowledge in the relevant art. And that modifications and variations which do not depart from the spirit and scope of the invention are intended to be within the scope of the appended claims.

Claims (7)

1. An optical module testing device comprises a to-be-miscoded instrument, a testing board and an optical module to be tested; the optical module to be tested is arranged on the test board; the error code instrument is connected with the test board, and is characterized in that:

the test board outputs the optical signal of the optical module to be tested to the test device;

the testing device comprises a first photodiode PIN1, a second photodiode PIN2, a first transimpedance amplifier TIA1, a second transimpedance amplifier TIA2 and a filter;

the first photodiode PIN1 receives an optical signal of the optical module to be detected, converts the optical signal into a current signal, and outputs the current signal to the first transimpedance amplifier TIA1;

the first transimpedance amplifier TIA1 converts a current signal into a voltage signal and outputs the voltage signal to the filter;

the filter outputs the filtered voltage signal to the peak value detection circuit;

the peak detection circuit outputs peak voltage adc1 to the MCU computing unit;

the second photodiode PIN2 receives an optical signal of the optical module to be detected, converts the optical signal into a current signal, and outputs the current signal to the second transimpedance amplifier TIA2;

the second transimpedance amplifier TIA2 converts the current signal into a voltage signal and outputs the voltage signal adc2 to the MCU computing unit;

the MCU computing unit performs processing operation to obtain a corresponding extinction ratio ER; the MCU computing unit can discharge the peak detection circuit.

2. The optical module testing device according to claim 1, wherein: the first transimpedance amplifier TIA1 is a high-speed transimpedance amplifier and outputs high-speed current change to be a high-speed voltage change signal.

3. The optical module testing device according to claim 1, wherein: the second transimpedance amplifier TIA2 is a low-speed transimpedance amplifier, and amplifies an average voltage value of the output photocurrent, where the average voltage value corresponds to an average optical power Pavg of the optical signal.

4. The optical module testing device according to claim 1, wherein: the filter is a two-stage low-pass filter and is used for filtering out unwanted noise and overshoot so as to match the speed of the current optical module and keep the stable test of the level.

5. The optical module testing device according to claim 1, wherein: the first photodiode PIN1 and the second photodiode PIN2 are PIN type photodiodes, one end of each of the first photodiode PIN1 and the second photodiode PIN2 is loaded with a direct BIAS voltage BIAS, and optical signals can be converted into high-speed changing current signals.

6. The optical module testing device according to claim 1, wherein: the optical splitter also comprises an adjustable attenuator and an optical splitter; the adjustable attenuator is connected with the test board and the test device at the same time; the optical signals firstly enter the adjustable attenuator and then are output to a first photodiode PIN1 and a second photodiode PIN2 in the testing device after being split by the optical splitter.

7. A method of calibrating an optical module testing device based on the optical module testing device according to claims 1-6, characterized in that: the method comprises the following steps:

s1, transmitting an optical signal of an optical module to be tested into an adjustable attenuator, a standard optical power meter and a standard optical oscilloscope for simultaneous test; the optical signals entering the adjustable attenuator are respectively sent into a first photodiode PIN1 and a second photodiode PIN2 in the testing device through an optical branching device; s2, recording the model of the current optical module to be tested, binding the calibration parameters with the model, and setting corresponding speed and code type parameters corresponding to the model by BERT;

s3, dividing the optical power range into N equal parts according to the accuracy required to be regulated, setting the optical power output value from Pavg_min to Pavg_max in a constant stepping way, respectively recording the adc2 amounts of a standard optical power meter and a testing device, and performing piecewise linear calibration;

s4, calibrating ER values, specifically comprising:

s41, fixing input optical power, and adjusting attenuation in real time through an adjustable attenuator to ensure constant optical power input into the testing device;

s42, changing parameters of the optical module, under the condition of ensuring constant optical power, setting the optical module from the minimum value to the maximum value of ER (ER), determining the step size according to the required test precision, recording the ER value of the standard optical oscilloscope and the adc1 amount of the test device, and performing piecewise linear calibration;

s43, storing the calibration coefficient into an MCU (micro control unit) computing unit of the testing device, and corresponding to the corresponding optical module model;

s5, removing the standard optical power meter and the standard optical oscilloscope.

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