Method and circuit for expanding receiving optical power calibration range of optical module

Abstract

The invention provides a method and a circuit for expanding a calibration range of received optical power of an optical module, relates to the technical field of optical power calibration, and aims to expand the calibration range of the received optical power of the optical module. The circuit comprises an ROSA module, a mirror image branch, a multi-path output branch, a filtering module and a micro-control unit; one end of each output branch is connected to a receiving power analog-to-digital conversion end of the micro-control unit, one end of each output branch is connected to the input end of the filtering module and one end of the mirror image branch, the output end of the filtering module is connected with the input end of the ROSA module, and the mirror image branch and the multiple output branches are connected to the direct current source; mirror current mirrors are formed by the multiple output branches and the mirror branches respectively. The device and the method have the advantage that the range of the received optical power capable of being accurately calibrated can be expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of optical power calibration, and in particular to a method and a circuit for expanding the calibration range of optical power received by an optical module. Background Art

[0002] Fiber-optic communication has the advantages of large communication capacity, long relay distance, and good confidentiality. As a key component for completing photoelectric / electro-optical conversion in fiber-optic communication, optical modules are widely used in data centers, telecommunications, power energy systems and other fields.

[0003] DDM (Digital Diagnostic Monitoring) specifies the standard values ​​or ranges that the software and hardware of optical modules and network equipment must follow, ensuring the interoperability of products provided by network equipment suppliers and optical module suppliers. DDM is a real-time parameter monitoring technology for optical modules, including the monitoring of operating voltage, operating temperature, received optical power, transmitted optical power and laser bias current. Through real-time monitoring of operating voltage, temperature, emitting power, received optical power and bias current by DDM, the working status of the optical module and the entire network system can be accurately judged. DDM monitoring is widely used in fault prediction and fault location. The calibration of the optical module receiving end usually uses the microcontroller unit MCU to collect the voltage value formed on the sampling resistor by the photocurrent flowing through the photoelectric tube PD at the receiving end of the optical module through the ADC port, and converts it to the actual received optical power value to achieve the calibration of the optical module receiving optical power. However, due to the limitation of MCU's ADC sampling accuracy, the range of accurate calibration of received optical power is limited, usually about 20dB. For some long-distance optical modules, the output optical power is large and the sensitivity requirement is high, but the received calibration power range is limited to only 20dB, which may cause inaccurate small light and saturation of large light.

[0004] Therefore, it is urgent to optimize and expand the calibration range of the optical module's received optical power. Summary of the invention

[0005] The object of the present invention is to provide a method and a circuit for expanding the calibration range of the optical power received by an optical module, which expands the calibration range of the optical power received by the optical module.

[0006] The present invention is achieved through the following technical solutions:

[0007] A circuit for expanding the calibration range of optical module receiving optical power, comprising a ROSA module, a mirror branch, a multi-channel output branch, a filter module and a micro control unit;

[0008] One end of each output branch is respectively connected to a receiving power analog-to-digital conversion end of the microcontroller unit, one end of each output branch is connected to the input end of the filter module and one end of the mirror branch, the output end of the filter module is connected to the input end of the ROSA module, and the mirror branch and multiple output branches are connected to a DC source;

[0009] The plurality of output branches respectively form a mirror current mirror with the mirror branch;

[0010] Each output branch is used to calibrate optical power signals in different power ranges.

[0011] Preferably, the number of the output branches is three, including a first output branch, a second output branch and a third output branch.

[0012] Preferably, the output branch includes a triode and a plurality of resistors;

[0013] The first output branch includes a second resistor, a second triode and a fifth resistor, one end of the second resistor is connected to a DC source and the other end is connected to the emitter of the second triode, the base of the second triode is connected to the input end of the filter module and one end of the mirror branch, the collector of the second triode is connected to one end of the fifth resistor, and the other end of the fifth resistor is grounded;

[0014] The second output branch includes a third resistor, a third triode and a sixth resistor, one end of the third resistor is connected to a DC source and the other end is connected to the emitter of the third triode, the base of the third triode is connected to the input end of the filter module and one end of the mirror branch, the collector of the third triode is connected to one end of the sixth resistor, and the other end of the sixth resistor is grounded;

[0015] The third output branch includes a fourth resistor, a fourth transistor and a seventh resistor, one end of the fourth resistor is connected to a DC source and the other end is connected to the emitter of the fourth transistor, the base of the fourth transistor is connected to the input end of the filter module and one end of the mirror branch, the collector of the fourth transistor is connected to one end of the seventh resistor, and the other end of the seventh resistor is grounded.

[0016] Preferably, the mirror branch includes a first resistor and a first transistor;

[0017] One end of the first resistor is connected to a DC source and the other end is connected to the emitter of the first transistor;

[0018] The base of the first transistor is connected to the base of the second transistor, the base of the third transistor and the base of the fourth transistor;

[0019] The base of the first transistor and the collector of the first transistor are both connected to the input end of the filter module.

[0020] Preferably, the ROSA module comprises a photodiode and a transimpedance amplifier;

[0021] The cathode of the photodiode is connected to the output end of the filter module, and the anode of the photodiode is connected to the input end of the transimpedance amplifier.

[0022] Preferably, the filtering module adopts an LC filtering network, including a first inductor and a first capacitor;

[0023] The first end of the first inductor serves as the input end of the filter module, the second end of the first inductor is connected to the input end of the ROSA module and one end of the first capacitor, and the other end of the first capacitor is grounded.

[0024] In order to solve the above problems, the present invention also provides a method for expanding the calibration range of the optical module receiving optical power, which is applied to the above-mentioned circuit for expanding the calibration range of the optical module receiving optical power, and includes the following steps:

[0025] Applying optical power to the photoelectric conversion chip in the ROSA module to form a first photocurrent signal;

[0026] Providing stable power supply to the photoelectric conversion chip through the filter module;

[0027] Based on the first photocurrent signal, a second photocurrent signal is generated on the output branch through the mirror branch, and a sampling voltage is formed for sampling calibration;

[0028] The micro control unit collects the sampled voltage.

[0029] Preferably, the second photocurrent signal and the first photocurrent signal are in a linear relationship.

[0030] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0031] The present invention can greatly expand the accurate calibration range of received optical power according to the requirements of different distances;

[0032] The present invention can perform accurate DDM calibration when the input light power of the long-distance optical module is close to or even lower than the sensitivity, or when a short optical fiber is directly looped back, that is, when the light power entering the receiving end is equal to the module light power;

[0033] The multi-channel output branch and mirror current mirror design of the present invention realizes the effective expansion of the calibration range of the optical module receiving optical power, and improves the dynamic adaptability and measurement accuracy of the system;

[0034] The present invention has a simple implementation method and low cost, and the resistance value of the sampling resistor can be adjusted according to actual needs to achieve calibration of the incident light size within a specific power range. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the structure of a circuit for extending the calibration range of optical module receiving optical power provided in Embodiment 1 of the present invention;

[0036] Figure 2 A schematic diagram of the current flow of a circuit for expanding the calibration range of optical module receiving optical power provided in Embodiment 1 of the present invention;

[0037] Figure 3 A schematic diagram of power segment calibration provided in Embodiment 1 of the present invention;

[0038] Icon: R1-first resistor, R2-second resistor, R3-third resistor, R4-fourth resistor, R5-fifth resistor, R6-sixth resistor, R7-seventh resistor, Q1-first transistor, Q2-second transistor, Q3-third transistor, Q4-fourth transistor, L1-first inductor, C1-first capacitor, D1-photodiode, U1-transimpedance amplifier, U2-micro control unit. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0040] Example 1

[0041] This embodiment provides a circuit for extending the calibration range of the optical module receiving optical power. Figure 1 , including a ROSA module, a mirror branch, a multi-channel output branch, a filter module and a micro control unit U2;

[0042] One end of each output branch is respectively connected to a receiving power analog-to-digital conversion end of the micro control unit U2, one end of each output branch is connected to the input end of the filter module and one end of the mirror branch, the output end of the filter module is connected to the input end of the ROSA module, and the mirror branch and multiple output branches are connected to a DC source;

[0043] The plurality of output branches respectively form a mirror current mirror with the mirror branch;

[0044] Each output branch is used to calibrate optical power signals in different power ranges.

[0045] In this embodiment, the number of the output branches is three, including a first output branch, a second output branch and a third output branch.

[0046] Further, the output branch includes a triode and a plurality of resistors;

[0047] The first output branch includes a second resistor R2, a second transistor Q2 and a fifth resistor R5, one end of the second resistor R2 is connected to a DC source and the other end is connected to the emitter of the second transistor Q2, the base of the second transistor Q2 is connected to the input end of the filter module and one end of the mirror branch, the collector of the second transistor Q2 is connected to one end of the fifth resistor R5, and the other end of the fifth resistor R5 is grounded;

[0048] The second output branch includes a third resistor R3, a third triode Q3 and a sixth resistor R6, one end of the third resistor R3 is connected to a DC source and the other end is connected to the emitter of the third triode Q3, the base of the third triode Q3 is connected to the input end of the filter module and one end of the mirror branch, the collector of the third triode Q3 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is grounded;

[0049] The third output branch includes a fourth resistor R4, a fourth transistor Q4 and a seventh resistor R7, one end of the fourth resistor R4 is connected to a DC source and the other end is connected to the emitter of the fourth transistor Q4, the base of the fourth transistor Q4 is connected to the input end of the filter module and one end of the mirror branch, the collector of the fourth transistor Q4 is connected to one end of the seventh resistor R7, and the other end of the seventh resistor R7 is grounded.

[0050] On the other hand, the mirror branch includes a first resistor R1 and a first transistor Q1;

[0051] One end of the first resistor R1 is connected to a DC source and the other end is connected to the emitter of the first transistor Q1;

[0052] The base of the first transistor Q1 is connected to the base of the second transistor Q2, the base of the third transistor Q3 and the base of the fourth transistor Q4;

[0053] The base of the first transistor Q1 and the collector of the first transistor Q1 are both connected to the input end of the filter module.

[0054] In addition, the ROSA module preferably includes a photodiode D1 and a transimpedance amplifier U1;

[0055] The cathode of the photodiode D1 is connected to the output end of the filter module, and the anode of the photodiode D1 is connected to the input end of the transimpedance amplifier U1.

[0056] As a preferred solution, the filtering module preferably adopts an LC filtering network, including a first inductor L1 and a first capacitor C1;

[0057] A first end of the first inductor L1 serves as an input end of the filter module, a second end of the first inductor L1 is connected to an input end of the ROSA module and one end of the first capacitor C1 , and the other end of the first capacitor C1 is grounded.

[0058] See the circuit diagram for current flow Figure 2 , the circuit working principle of this embodiment is as follows:

[0059] In this embodiment, the emitter of the first transistor Q1 is connected to the DC source VCC through the first resistor R1, and the base and the pole of the first transistor Q1 are connected together, and then connected to the cathode of the photodiode D1 after passing through the LC filter network composed of the first inductor L1 and the first capacitor C1 to provide power to the photodiode D1. When there is light power input, the photodiode D1 will generate a photocurrent I 1 , photocurrent I 1 The size is related to the incident light and PD responsivity.

[0060] In several output branches, the emitter of the second transistor Q2 is connected to the DC source VCC through the second resistor R2. Since the base of the second transistor Q2 is connected to the base and collector of the first transistor Q1, and the emitter of the second transistor Q2 is connected to the second resistor R2 as a current regulating resistor, and the second transistor Q2 is connected to the first receiving power analog-to-digital conversion terminal ADC1 of the micro control unit U2 and the voltage it receives comes from the voltage of the fifth resistor R5 as a sampling resistor, therefore, the first transistor Q1 and the second transistor Q2 form a 1:1 mirror current mirror. At this time, the resistance values ​​of the first resistor R1 and the second resistor R2 are set to be equal, then the current I flowing through the second resistor R2 is 2 Equal to the photocurrent I flowing through the photodiode D1 1 ;

[0061] The emitter of the third transistor Q3 is connected to the DC source VCC through the third resistor R3, and the base of the third transistor Q3 is connected to the base and collector of the first transistor Q1, and the emitter of the third transistor Q3 is connected to a third resistor R3 as a current regulating resistor, and the third transistor D3 is also connected to the second receiving power analog-to-digital conversion terminal ADC2 of the micro control unit U2 and the voltage received by it comes from the voltage of the sixth resistor R6 as a sampling resistor, and the resistance value of the third resistor R3 can be set to be 10 times the resistance value of the first resistor R1. At this time, the first transistor Q1 and the third transistor Q3 form a 10:1 mirror current mirror, and the current I flowing through the third resistor R3 3 Equal to one tenth of the photocurrent I flowing through the photodiode D1 1 / 10;

[0062] Similarly, the emitter of the fourth transistor Q4 is connected to the DC source VCC through the fourth resistor R4, and since the base of the fourth transistor Q4 is connected to the base and collector of the first transistor Q1, and the emitter of the fourth transistor Q4 is connected to the fourth resistor R4 as a current regulating resistor, and the fourth transistor Q4 is connected to the third receiving power analog-to-digital conversion terminal ADC3 of the micro control unit U2 and the voltage received by it comes from the voltage of the seventh resistor R7 as a sampling resistor, the resistance of the fourth resistor R4 can be set to 100 times that of the first resistor R1. At this time, the first transistor Q1 and the fourth transistor Q4 form a 100:1 mirror current mirror, and the current I flowing through the fourth resistor R4 is 4 Equal to one percent of the photocurrent I flowing through the photodiode D1 1 / 100;

[0063] In summary, I 1 =I 2 =10*I 3 =100*I 4 .

[0064] Based on the above principle, let I i is the current flowing through the i-th resistor, let r i is the resistance value of the i-th resistor, i=1,2,…,7. When the calibration module receives the optical power DDM, the following resistance relationship is set: 7 =100r 5 , r 6 =10r 5 , that is, r 7 =10r 6 =100r 5 .

[0065] The collected voltage of the first receiving power analog-to-digital conversion terminal ADC1 of the micro control unit U2 is I 2 *r 5 =I1 *r 5 ;

[0066] The acquisition voltage of the second received power analog-to-digital conversion terminal ADC2 of the microcontroller unit U2 is I 3 *r 6 = 10*I 1 *10r 5 = 100*I 1 *r 5 ;

[0067] The acquisition voltage of the third received power analog-to-digital conversion terminal ADC3 of the microcontroller unit U2 is I 4 *r 7 = 100*I 1 *100r 5 = 10000*I 1 *r 5 .

[0068] Ideally, the relationship between the PD response current and the optical power is 1 A / W, that is, 1 mA / mW. Therefore, the optical power received by the module's receiving end and the response current I flowing through the PD 1 The relationship is shown in Table 1 below:

[0069] Table 1 Relationship between incident optical power and response current

[0070] Optical power (dBm) -60 -50 -40 -30 -20 -10 0 Response current (mA) 0.000001 0.00001 0.0001 0.001 0.01 0.1 1

[0071] When each of the output branches is used to calibrate the optical power signals in different power ranges, the optical power received by the module is RX power, and the microcontroller unit makes the following settings:

[0072] When -60 dBm ≤ Rx power ≤ -40 dBm, the acquisition value of RX Power ADC3 and ADC3 are used for power calibration;

[0073] When -40 dBm < Rx power ≤ -20 dBm, the acquisition value of RX Power ADC2 and ADC2 are used for power calibration;

[0074] When -20 dBm < Rx power ≤ 0 dBm, the acquisition value of RX Power ADC1 and ADC1 are used for power calibration;

[0075] Schematic diagram of three-power segmented calibration Figure 3 is shown as follows.

[0076] Embodiment 2

[0077] This embodiment provides a method for extending the calibration range of received optical power of an optical module, which is applied to a circuit for extending the calibration range of received optical power of an optical module provided in Embodiment 1, and includes the following steps:

[0078] The optical power is irradiated on a photoelectric conversion chip such as a photodiode in the ROSA module to form a first photocurrent signal;

[0079] Providing stable power supply to the photoelectric conversion chip through the filter module;

[0080] Based on the first photocurrent signal, a second photocurrent signal is generated on the output branch through the mirror branch, and a sampling voltage is formed for sampling calibration;

[0081] The micro control unit collects the sampled voltage.

[0082] In this embodiment, the second photocurrent signal and the first photocurrent signal are in a linear relationship.

[0083] The following provides a specific implementation case based on the technical solution of this embodiment. i is the current flowing through the i-th resistor, let r i is the resistance of the i-th resistor, i=1,2,…,7:

[0084] Setting 1 =200Ω, r 2 =200Ω, r 3 =20Ω, r 4 =2Ω, r 5 =2.4KΩ, r 6 =24KΩ, r 7 =240KΩ; Set the sampling reference voltage VREF=2.4V, that is, the sampling saturation value is 2.4V, and the module receives the optical power RX power, then:

[0085] I 1 =10^(RX power / 10);

[0086] I 2 =I 1 =10^(RX power / 10);

[0087] I 3 =I 1 / 10=(10^(RX power / 10)) / 10;

[0088] I 4 =I 1 / 100=(10^(RX power / 10)) / 100;

[0089] The sampling voltages of the first receiving power analog-to-digital conversion terminal ADC1, the first receiving power analog-to-digital conversion terminal ADC2 and the first receiving power analog-to-digital conversion terminal ADC3 of the micro control unit are respectively:

[0090] ADC1 = I 2 *r 5 =10^(RX power / 10)*2.4*1000;

[0091] ADC2 = I 3 *r 6 =(10^(RX power / 10)) / 10*24*1000;

[0092] ADC3 = I 4 *r 7 =(10^(RX power / 10)) / 100*240*1000;

[0093] When the optical module receives optical power of -60dBm to 0dBm, the corresponding current and each ADC voltage sampling value are shown in Table 2:

[0094] Table 2 Relationship between current and ADC sampling value when the optical power is -60dBm to 0dBm

[0095]

[0096]

[0097] The microcontroller unit is set as follows:

[0098] 24mv≤ADC3<2400mv and ADC2<30mv, use ADC3 channel to report -60~-40dBm calibration value;

[0099] 30mv≤ADC2<2400mv and ADC1<30mv, use ADC2 channel to report -40~-20dBm calibration value;

[0100] 30mv≤ADC1<2400mv and ADC2>2400mv, use ADC1 channel to report -20~0dBm calibration value.

[0101] In summary, this embodiment can expand the accurate calibration range of the received optical power to 40dB, 60dB, or even wider range according to the requirements of different distances. For a long-distance optical module, even if the input optical power is close to or even lower than the sensitivity, the DDM calibration of the optical power at the module receiving end can still be very accurate; even if a short optical fiber is used for direct loopback, that is, when the optical power entering the receiving end is equal to the module luminous power, the DDM calibration of the optical power at the module receiving end can still be very accurate. With accurate DDM calibration, users can correctly judge the operating status of the module based on the real-time monitored DDM optical power.

[0102] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A circuit for extending the calibration range of optical module receiving optical power, characterized in that: It includes a ROSA module, a mirror branch, a multi-channel output branch, a filter module and a micro control unit; One end of each output branch is respectively connected to a receiving power analog-to-digital conversion end of the microcontroller unit, one end of each output branch is connected to the input end of the filter module and one end of the mirror branch, the output end of the filter module is connected to the input end of the ROSA module, and the mirror branch and multiple output branches are connected to a DC source; The plurality of output branches respectively form a mirror current mirror with the mirror branch; Each output branch is used to calibrate optical power signals in different power ranges.

2. A circuit for extending the calibration range of received optical power of an optical module according to claim 1, characterized in that: The number of the output branches is three, including a first output branch, a second output branch and a third output branch.

3. A circuit for extending the calibration range of received optical power of an optical module according to claim 2, characterized in that: The output branch includes a triode and a plurality of resistors; The first output branch includes a second resistor, a second triode and a fifth resistor, one end of the second resistor is connected to a DC source and the other end is connected to the emitter of the second triode, the base of the second triode is connected to the input end of the filter module and one end of the mirror branch, the collector of the second triode is connected to one end of the fifth resistor, and the other end of the fifth resistor is grounded; The second output branch includes a third resistor, a third triode and a sixth resistor, one end of the third resistor is connected to a DC source and the other end is connected to the emitter of the third triode, the base of the third triode is connected to the input end of the filter module and one end of the mirror branch, the collector of the third triode is connected to one end of the sixth resistor, and the other end of the sixth resistor is grounded; The third output branch includes a fourth resistor, a fourth transistor and a seventh resistor, one end of the fourth resistor is connected to a DC source and the other end is connected to the emitter of the fourth transistor, the base of the fourth transistor is connected to the input end of the filter module and one end of the mirror branch, the collector of the fourth transistor is connected to one end of the seventh resistor, and the other end of the seventh resistor is grounded.

4. A circuit for extending the calibration range of received optical power of an optical module according to claim 3, characterized in that: The mirror branch includes a first resistor and a first transistor; One end of the first resistor is connected to a DC source and the other end is connected to the emitter of the first transistor; The base of the first transistor is connected to the base of the second transistor, the base of the third transistor and the base of the fourth transistor; The base of the first transistor and the collector of the first transistor are both connected to the input end of the filter module.

5. A circuit for extending the calibration range of received optical power of an optical module according to claim 1, characterized in that: The ROSA module includes a photodiode and a transimpedance amplifier; The cathode of the photodiode is connected to the output end of the filter module, and the anode of the photodiode is connected to the input end of the transimpedance amplifier.

6. A circuit for extending the calibration range of received optical power of an optical module according to claim 1, characterized in that: The filtering module adopts an LC filtering network, including a first inductor and a first capacitor; The first end of the first inductor serves as the input end of the filter module, the second end of the first inductor is connected to the input end of the ROSA module and one end of the first capacitor, and the other end of the first capacitor is grounded.

7. A method for extending the calibration range of received optical power of an optical module, applied to a circuit for extending the calibration range of received optical power of an optical module as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: Applying optical power to the photoelectric conversion chip in the ROSA module to form a first photocurrent signal; Providing stable power supply to the photoelectric conversion chip through the filter module; Based on the first photocurrent signal, a second photocurrent signal is generated on the output branch through the mirror branch, and a sampling voltage is formed for sampling calibration; The micro control unit collects the sampled voltage.

8. A method for extending the calibration range of received optical power of an optical module according to claim 7, characterized in that: The second photocurrent signal is linearly related to the first photocurrent signal.

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