Pulsed Light Peak Power Measurement Circuit, Device and Measurement Method

Abstract

The present invention provides a pulsed light peak power measurement circuit, device and measurement method. Among them, the measurement device includes a measurement circuit, a power supply, a pulsed light to be measured and a computer. The power supply is connected to the measurement circuit; the pulsed light to be measured is injected into the pulsed light injection interface of the measurement circuit; the I2C interface of the measurement circuit establishes a communication link with the computer through an I2C to USB connector, and the computer obtains the pulsed light peak power reported by the MCU through this link. The present invention can adapt to the pulsed light signal to be measured. It only needs the pulsed light to be measured to be input, without the need to additionally output an electrical signal for driving the pulsed light laser to be measured. The pulsed light device to be measured also does not need to provide a synchronous pulse clock output interface, and the pulsed light peak power can be tested. The test is flexible and has strong compatibility. It can dynamically refresh the pulsed peak change and reflect the height of the peak amplitude.

Description

Technical Field

[0001] The present invention belongs to the technical field of peak power measurement, and more particularly relates to a pulsed light peak power measurement circuit, device, and measurement method. Background Art

[0002] Currently, optical power meters are usually used to measure the average optical power of continuous light. If pulsed light is injected, the optical power meter only measures the average optical power of the pulsed light, rather than the peak power of the pulsed light. Affected by the pulse width and pulse period, the power readings displayed by the optical power meter are different.

[0003] There are few devices on the market for measuring the peak power of pulsed light. Although some manufacturers have devices or solutions for measuring the peak power of pulsed light, they need to provide drive signals such as pulse period and pulse width to the laser module under test.

[0004] However, since the laser under test is a delicate and critical device, it usually does not provide an external drive interface to prevent damage to the laser caused by incorrect user operations. Therefore, such pulsed light peak power measurement devices can test limited products and have low compatibility.

[0005] Alternatively, some manufacturers design pulsed light peak power measurement devices that require the drive module of the pulsed light under test to provide signals such as a synchronous pulse clock to the device. However, the pulsed light device under test may not specifically reserve a synchronous pulse clock output interface for testing the peak power of pulsed light. Therefore, the use of such pulsed light peak power measurement devices is also limited.

[0006] Or, some manufacturers use a pulse peak hold circuit to sample the input pulsed light to adjust the peak power of the laser pulsed light. This peak hold circuit tracks and holds the peak of the input signal, and the output signal remains at the maximum peak of the input signal and lasts for a period of time until a larger peak appears. Therefore, if the pulse peak of the input signal fluctuates, the peak hold circuit only refreshes the maximum peak at the output, and the values below the peak are ignored, and it cannot reflect the height of the peak amplitude. The peak hold circuit is widely used in automatic gain control circuits to control the optical power emitted by the laser within a certain range. Moreover, the design of the time constant in the peak hold circuit is very important. If the time constant is too large, the peak held at the output is relatively stable, but the response time is longer. If the time constant is too small, the response time is shorter, but the output fluctuates greatly and the peak may be inaccurate. Therefore, a reasonable time constant needs to be designed for the pulse period of the input signal, and there is a limit to the frequency of the input pulsed light to be measured, and the applicability is low.

[0007] In addition, for application scenarios with long-distance transmission, such as 20 km / 40 km optical fiber communication scenarios, these devices, due to the need for the supply of driving electrical signals, are only suitable for measuring back-to-back pulsed light and cannot detect the peak power of pulsed light at the far end.

[0008] In summary, there is an urgent need for a new pulsed light peak power measurement device that can support the detection of pulsed light peak power after long-distance transmission, without the need for the pulsed light module under test to provide a corresponding clock signal or for the pulsed light peak power meter to provide a driving signal to the pulsed light device under test, has no strict restrictions on the frequency of the input pulsed light to be measured, is flexibly compatible with the pulsed light to be measured, can dynamically refresh the pulsed peak change, and reflect the high and low peak amplitudes. Summary of the Invention

[0009] To solve the above problems, the present invention provides a pulsed light peak power measurement circuit, device, and measurement method. The measurement device has the function of extracting the pulsed light period signal and synchronizing the clock, has no strict restrictions on the frequency of the input pulsed light to be measured, can accurately sample the pulsed light peak power, and as long as the pulsed light to be measured is injected into the optical input interface of the measurement circuit, the magnitude of the pulsed light peak power can be reported.

[0010] In the first aspect, the present invention provides a pulsed light peak power measurement circuit, which includes:

[0011] An optical pulse clock signal extraction unit, a sampling signal generation unit, a trigger signal generation unit, and a light power reporting unit MCU.

[0012] The optical pulse clock signal extraction unit includes a photodiode, a photodiode driving module, and an operational amplifier. The photodiode is connected to the pulsed light injection interface. The photodiode driving module is connected to the photodiode to provide voltage for the photodiode, and the photodiode driving module is also connected to the input end of the operational amplifier;

[0013] The sampling signal generation unit includes an edge-triggered pulse generator, a delay unit, and a digital logic module. The input end of the edge-triggered pulse generator and the input end of the delay unit are respectively connected to the output end of the operational amplifier. The output end of the edge-triggered pulse generator and the output end of the delay unit are respectively connected to the input end of the digital logic module;

[0014] The trigger signal generation unit includes a frequency divider. The input end of the frequency divider is connected to the output end of the digital logic module;

[0015] The input end of the light power reporting unit MCU is connected to the output end of the frequency divider, and the output end of the MCU is connected to the I2C interface; the I2C interface is a user interface for accessing the measurement circuit, can read and write the MCU, and the user can read the reported value of the pulsed light peak power.

[0016] In a second aspect, the present invention provides a pulsed light peak power measurement device, which includes the aforementioned measurement circuit, and further includes a power supply, a pulsed light to be measured, and a computer. The power supply is connected to the positive voltage interface VCC and the ground interface GND of the power supply of the measurement circuit; the pulsed light to be measured is injected into the pulsed light injection interface of the measurement circuit; the I2C interface of the measurement circuit establishes a communication link with the computer through an I2C to USB connector, and the computer obtains the pulsed light peak power reported by the MCU through this link.

[0017] In a third aspect, the present invention further provides a method for measuring the pulsed light peak power using the aforementioned measurement device, and this method includes:

[0018] Extracting the clock signal carried by the periodic optical pulse through the measurement circuit;

[0019] Generating a sampling signal through the clock signal, such that the edge of the sampling signal lags behind the rising edge of the optical pulse and is located at a position where the power of the optical pulse is relatively stable;

[0020] Reducing the frequency of the sampling signal, generating a trigger signal and sending it to the MCU to avoid frequent and excessive triggering of the MCU interrupt, which may cause abnormal operation of the MCU;

[0021] When the MCU receives the trigger signal, sampling the amplitude of the optical pulse and converting the sampling result into an optical power value.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The measurement device provided by the present invention can adapt to the pulsed light signal to be measured through the measurement circuit. Only the pulsed light to be measured needs to be input, and there is no need to additionally output an electrical signal for driving the pulsed light laser. The pulsed light device to be measured also does not need to provide a synchronous pulse clock output interface, and the pulsed light peak power can be tested. The test is flexible, has strong compatibility, can dynamically refresh the pulsed peak change, and reflects the high and low of the peak amplitude.

[0024] The measurement device provided by the present invention does not require an electrical signal to drive the laser, nor does it require the measured device to provide a synchronous clock interface for such an electrical signal. It can support the measurement of the pulsed light peak power after 20 km / 40 km long-distance optical fiber transmission. It can also improve the performance of the photodiode to enhance the receiving sensitivity and support longer-distance optical fiber transmission.

[0025] The measurement device provided by the present invention has a function of filtering stray light pulses, low noise, and high measurement accuracy.

[0026] The present invention does not save the pulsed peak, can dynamically refresh the pulsed peak change, and reflects the high and low of the peak amplitude. Description of the Drawings

[0027] Figure 1It is a circuit schematic diagram of the optical pulse clock signal extraction unit in the present invention;

[0028] Figure 2 It is a circuit schematic diagram of the sampling signal generation unit in the present invention;

[0029] Figure 3 It is a circuit schematic diagram of the trigger signal generation unit in the present invention;

[0030] Figure 4 It is a circuit schematic diagram of the MCU of the optical power reporting unit in the present invention;

[0031] Figure 5 It is a principle block diagram of the measuring device in the present invention;

[0032] Figure 6 It is a test connection schematic diagram of the measuring device in the present invention;

[0033] Figure 7 It is Figure 5 The timing diagram of the corresponding node;

[0034] Figure 8 It is the test data of the peak optical power of the pulsed light.

[0035] Label description: photodiode - 1, photodiode drive module - 2, operational amplifier - 3, edge - triggered pulse generator - 4, delay unit - 5, digital logic module - 6, frequency divider - 7, MCU - 8. Specific embodiments

[0036] To make the objectives, 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 with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0038] The present invention provides a pulsed light peak power measurement circuit, which includes an optical pulse clock signal extraction unit, a sampling signal generation unit, a trigger signal generation unit, and an optical power reporting unit MCU8.

[0039] As Figure 1As shown in the figure, the optical pulse clock signal extraction unit includes a photodiode 1, a photodiode driving module 2, and an operational amplifier 3. The photodiode 1 is connected to the pulsed light injection interface. The photodiode driving module 2 is connected to the photodiode 1 to provide voltage for the photodiode 1. The photodiode driving module 2 is also connected to the input terminal of the operational amplifier 3.

[0040] As Figure 2 shown in the figure, the sampling signal generation unit includes an edge-triggered pulse generator 4, a delay unit 5, and a digital logic module 6. The input terminals of the edge-triggered pulse generator 4 and the delay unit 5 are respectively connected to the output terminal of the operational amplifier 3. The output terminals of the edge-triggered pulse generator 4 and the delay unit 5 are respectively connected to the input terminals of the digital logic module 6.

[0041] As Figure 3 shown in the figure, the trigger signal generation unit includes a frequency divider 7. The input terminal of the frequency divider 7 is connected to the output terminal of the digital logic module 6.

[0042] As Figure 4 shown in the figure, the input terminal of the optical power reporting unit MCU8 is connected to the output terminal of the frequency divider 7. The output terminal of the MCU8 is connected to the I2C interface. The I2C interface is a user interface for accessing the measurement circuit, capable of reading and writing the MCU8. The user can read the reported value of the pulsed light peak power.

[0043] The measurement circuit also includes a power supply positive voltage interface VCC and a power supply ground interface GND, providing a power input port for the normal operation of the measurement circuit.

[0044] In this embodiment, the pulsed light injection interface is the input port of the pulsed light to be measured. The pulsed light to be measured enters the photodiode 1 through the pulsed light injection interface. The photodiode 1 converts the optical signal of the pulsed light to be measured into an electrical signal. The photodiode driving module 2 sends the pulsed light current signal I_OpSig after photoelectric conversion to the MCU8 for its sampling to report the peak optical power. At the same time, the detected pulsed light voltage signal V_OpSig is sent to the operational amplifier 3. The operational amplifier 3 shapes the voltage signal V_OpSig and extracts the pulsed light clock signal PulseSig.

[0045] The clock signal PulseSig enters the sampling signal generation unit. A part of it inputs to the edge-triggered pulse generator 4 to generate a periodic pulse signal PulseGen. By configuring the edge-triggered pulse generator 4, the width of the periodic pulse signal PulseGen is adjusted to filter out stray small pulses, and only the pulsed light with a specific pulse width is sampled to improve the sampling accuracy. Another part adds a time delay to the clock signal PulseSig through the delay unit 5, making the edge of the signal lag behind the edge of the periodic pulse signal PulseGen to generate PulseSigDelay. These two output signals are operated by the digital logic module 6 to generate the sampling signal SampleGen. At this time, the rising edge of the sampling signal SampleGen lags behind the rising edge of PulseSig and is located at a relatively stable position of the peak value of the pulsed photocurrent signal I_OpSig.

[0046] The sampling signal SampleGen passes through the frequency divider 7 of the trigger signal generation unit, and its frequency is reduced to generate the trigger signal TriggerOUT.

[0047] After the MCU8 of the optical power reporting unit receives the valid TriggerOUT signal, according to the operating mechanism of the MCU8, it samples the pulsed photocurrent signal I_OpSig, and the MCU8 internally quantifies and calculates the sampling result. The user reads the peak power of the pulsed light reported by the MCU8 through the I2C interface.

[0048] In specific implementation, the MCU8 can sample the pulsed photocurrent signal I_OpSig multiple times and take the average value of the sampling results to improve the accuracy and repeatability of the pulsed light peak power test.

[0049] The present invention also provides a pulsed light peak power measurement device, whose principle block diagram is as Figure 5 shown, and the test connection schematic diagram is as Figure 6 shown. The measurement device includes the measurement circuit mentioned above, and also includes a power supply, the pulsed light to be measured, and a computer. The power supply is connected to the positive power supply voltage interface VCC and the power supply ground interface GND of the measurement circuit; the pulsed light to be measured is injected into the pulsed light injection interface of the measurement circuit; the I2C interface of the measurement circuit establishes a communication link with the computer through the I2C to USB connector, and the computer obtains the peak power of the pulsed light reported by the MCU8 through this link.

[0050] The present invention also discloses a method for measuring the peak power of pulsed light using the above measurement device. The measurement method includes the following steps:

[0051] After the pulsed light to be measured is injected into the measurement circuit, the clock signal carried by the periodic optical pulse is extracted through the measurement circuit;

[0052] A sampling signal is generated through a clock signal, such that the edge of the sampling signal lags behind the rising edge of the optical pulse and is located at a position where the power of the optical pulse is relatively stable;

[0053] The frequency of the sampling signal is reduced to generate a trigger signal and sent to the MCU8, avoiding frequent and excessive triggering of the MCU8 interrupt and causing abnormal operation of the MCU8;

[0054] When the MCU8 receives the trigger signal, it samples the amplitude of the optical pulse and converts the sampling result into an optical power value.

[0055] Figure 7 For Figure 5 The timing diagram of the corresponding nodes in the principle block diagram shown. In the figure, “...n Pulses” means there are n pulsed optical signals in between. The current signal I_OpSig indicates the current of the pulsed optical signal to be measured detected by the photodetector. The actual signal amplitude is proportional to the light intensity and is not as regular as shown in the timing diagram. The voltage signal V_OpSig passes through the shaping and clock extraction of the optical pulse clock signal extraction unit to output the pulsed optical clock signal PulseSig, and then enters the sampling signal generation unit. Among them, for example, the edge-triggered pulse generator 4 triggered by the rising edge, due to the delay of the device itself, after detecting the rising edge and experiencing tPHL, a low-level signal with a width of Tw can be set to be generated inside the module and then jump to the high level, as shown by the periodic pulse signal PulseGen. Another signal passes through the delay 5, adding a time delay of tPD to PulseSig, such that the rising edge of PulseSigDelay is located after the falling edge of PulseGen. Thus, through the digital logic module 6, a sampling signal SampleGen is generated, which can filter out the stray pulsed optical signals with a pulse width less than Tw, and the rising edge of SampleGen lags behind the rising edge of the current signal I_OpSig of the optical pulse to be measured and is located at a position where its amplitude is relatively stable. Since a sampling signal SampleGen is generated for each period of the pulsed optical clock signal PulseSig, if directly provided to the MCU8, it will frequently trigger the MCU8 interrupt and cause the system to crash. Therefore, the sampling signal SampleGen is input to the trigger signal generation unit for frequency reduction to generate a low-frequency trigger signal TriggerOUT and provided to the MCU8. The sampling working mode of the MCU8 can be set. For example, when detecting the rising edge of TriggerOUT to trigger the MCU8 interrupt, the pulsed optical current signal I_OpSig is sampled after a time delay of tSample. The MCU8 internally quantifies and calculates the sampling result according to the algorithm and reports the peak power of the pulsed optical at this time.

[0056] In the method for measuring the peak power of pulsed light, when the MCU8 receives a trigger signal, it samples the amplitude of the optical pulse to obtain the ADC value of the optical pulse amplitude at this time, and substitutes this ADC value into the fitting coefficient, such as linear fitting, y[mW]=f(ADCvalue)=k×ADCvalue+b to convert it into the optical power value.

[0057] Linear fitting, polynomial fitting or other fitting methods are selected according to the reporting accuracy and repeatability requirements of the peak power of pulsed light. Continuously inject light with known optical power, such as P0, P1, P2,... as Y, and respectively obtain ADCvalue0, ADCvalue1, ADCvalue2... as X through MCU sampling for multi-point fitting, and obtain the fitting coefficient according to the selected fitting method. This technology is an existing technology and will not be elaborated here.

[0058] Inject a pulsed light signal with a known peak optical power into the measuring device of the present invention for testing. The test data of the peak optical power of the pulsed light is as Figure 8 shown. The "actual peak power of pulsed light" is a pulsed light signal with a known peak optical power. In the test, pulsed light signals with pulse widths of 5us / 10us / 20us and periods of 100us / 796us are used. For each group of tests, 100 reported optical powers are read from the MCU8. "Max.", "Min." and "Avg." are the maximum, minimum and average values of these 100 reported optical powers respectively. The repeatability of the test results is ±0.2dB, and the accuracy is ±0.8dB. It should be noted that the repeatability and accuracy can be improved by replacing the MCU8 with higher performance, such as an ADC with a higher number of bits, or optimizing the algorithm.

[0059] The measuring device provided by the present invention can adapt to the pulsed light signal to be measured through the measuring circuit. Only the pulsed light to be measured needs to be input, and there is no need to additionally output an electrical signal to drive the pulsed light laser to be measured. The pulsed light device to be measured does not need to provide a synchronous pulse clock output interface either, and the peak power of the pulsed light can be tested.

[0060] The present invention has no strict limit on the frequency of the pulsed light input to be measured, is flexible in testing, has strong compatibility, and can support the measurement of the peak power of pulsed light after 20km / 40km long-distance optical fiber transmission. The receiving sensitivity can also be improved by enhancing the performance of the photodiode, so as to support longer-distance optical fiber transmission.

[0061] The measuring device provided by the present invention has the function of filtering stray light pulses, low noise, and high measurement accuracy. Moreover, it does not save the pulse peak, can dynamically refresh the change of the pulse peak, and reflect the height of the peak amplitude.

[0062] The above are only some embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the creative concept of the present invention, other variations and improvements can be made, and all of these fall within the protection scope of the present invention.

Claims

1. Pulse light peak power measurement circuit, characterized in that The measurement circuit includes an optical pulse clock signal extraction unit, a sampling signal generation unit, a trigger signal generation unit, and an optical power reporting unit MCU; The optical pulse clock signal extraction unit includes a photodiode, a photodiode drive module, and an operational amplifier. The photodiode is connected to the pulsed light injection interface. The photodiode drive module is connected to the photodiode to provide voltage for the photodiode. The photodiode drive module is also connected to the input terminal of the operational amplifier; The sampling signal generation unit includes an edge-triggered pulse generator, a delay unit, and a digital logic module. The input terminal of the edge-triggered pulse generator and the input terminal of the delay unit are respectively connected to the output terminal of the operational amplifier. The output terminal of the edge-triggered pulse generator and the output terminal of the delay unit are respectively connected to the input terminal of the digital logic module; The trigger signal generation unit includes a frequency divider. The input terminal of the frequency divider is connected to the output terminal of the digital logic module; The input terminal of the optical power reporting unit MCU is connected to the output terminal of the frequency divider. The output terminal of the MCU is connected to the I2C interface. The I2C interface is a user interface for accessing the measurement circuit, capable of reading and writing the MCU. The user can read the reported value of the pulsed light peak power; Among them, the clock signal carried by the periodic optical pulse is extracted by the optical pulse clock signal extraction unit. The sampling signal generation unit generates a sampling signal through the clock signal, and reduces the frequency of the sampling signal through the trigger signal generation unit to generate a trigger signal and send it to the MCU, avoiding frequent and excessive triggering of the MCU interrupt and causing abnormal operation of the MCU. When the MCU receives the trigger signal, it samples the optical pulse amplitude and converts the sampling result into an optical power value.

2. The measurement circuit according to claim 1, wherein The pulsed light injection interface is the input port of the pulsed light to be measured. The pulsed light to be measured enters the photodiode through the pulsed light injection interface, and the photodiode converts the optical signal of the pulsed light to be measured into an electrical signal; The photodiode drive module sends the pulse photocurrent signal I_OpSig after photoelectric conversion to the MCU for its sampling to report the peak optical power. At the same time, it sends the detected pulsed light voltage signal V_OpSig to the operational amplifier, and the operational amplifier shapes the voltage signal V_OpSig and extracts the pulsed light clock signal PulseSig.

3. The measuring circuit according to claim 2, characterized in that, The clock signal PulseSig enters the sampling signal generation unit. A part of it is input to the edge-triggered pulse generator to generate a periodic pulse signal PulseGen. By configuring the edge-triggered pulse generator, the width of the periodic pulse signal PulseGen is adjusted to filter out stray small pulses, and only the pulsed light with a specific pulse width is sampled, improving the sampling accuracy. Another part adds a time delay to the clock signal PulseSig through a delay element, making the edge of the signal lag behind the edge of the periodic pulse signal PulseGen to generate PulseSigDelay. These two output signals are operated on by a digital logic module to generate a sampling signal SampleGen. At this time, the rising edge of the sampling signal SampleGen lags behind the rising edge of PulseSig and is located at a relatively stable position of the peak value of the pulsed photocurrent signal I_OpSig.

4. The measuring circuit according to claim 3, characterized in that, The sampling signal SampleGen passes through the downscaler of the trigger signal generation unit, and its frequency is reduced to generate a trigger signal TriggerOUT.

5. The measuring circuit according to claim 4, characterized in that After the MCU of the optical power reporting unit receives the valid TriggerOUT signal, according to the operating mechanism of the MCU, it samples the pulsed photocurrent signal I_OpSig. The user reads the peak power of the pulsed light reported by the MCU through the I2C interface.

6. The measurement circuit according to claim 5, characterized in that, The MCU samples the pulsed photocurrent signal I_OpSig multiple times and takes the average value of the samples to improve the accuracy and repeatability of the pulsed light peak power measurement.

7. The measuring circuit according to claim 6, wherein The measurement circuit further includes a power supply positive voltage interface VCC and a power supply ground interface GND, providing a power input port for the normal operation of the measurement circuit.

8. A pulsed light peak power measurement device, comprising the measurement circuit according to any one of claims 1-7, characterized in that, It further includes a power supply, the pulsed light to be measured, and a computer. The power supply is connected to the power supply positive voltage interface VCC and the power supply ground interface GND of the measurement circuit. The pulsed light to be measured is injected into the pulsed light injection interface of the measurement circuit. The I2C interface of the measurement circuit establishes a communication link with the computer through an I2C to USB connector, and the computer obtains the peak power of the pulsed light reported by the MCU through this link.

9. A method for measuring the peak power of pulsed light using the measuring device according to claim 8, characterized in that, It includes: Extracting the clock signal carried by the periodic optical pulse through the measurement circuit; Generating a sampling signal through the clock signal, making the edge of the sampling signal relatively lag behind the rising edge of the optical pulse and being located at a position where the optical pulse power is relatively stable; Reducing the frequency of the sampling signal, generating a trigger signal and sending it to the MCU to avoid frequent and excessive triggering of the MCU interrupt, causing abnormal operation of the MCU; When the MCU receives the trigger signal, it samples the amplitude of the optical pulse and converts the sampling result into an optical power value.

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