Pulse light peak power measuring circuit, device and method

Abstract

The invention provides a pulse light peak power measuring circuit, device and method, the measuring device comprises a measuring circuit, a power supply, pulse light to be measured and a computer, and the power supply is connected with the measuring circuit; to-be-measured pulsed light is injected into a pulsed light injection interface of the measuring circuit; the I2C interface of the measuring circuit establishes a communication link with the computer through the I2C-to-USB connector, and the computer obtains the pulsed light peak power reported by the MCU through the link. The pulse light peak power testing device can be adaptive to the pulse light signal to be tested, only the pulse light to be tested needs to be input, an electric signal for driving the pulse light laser to be tested does not need to be additionally output, the pulse light device to be tested does not need to provide a synchronous pulse clock output interface, the pulse light peak power can be tested, testing is flexible, compatibility is high, and testing efficiency is high. The pulse peak change can be dynamically refreshed, and the peak amplitude can be reflected.

Description

Technical Field

[0001] The present invention belongs to the technical field of peak power measurement, and more particularly relates to a pulse 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 to be measured.

[0004] However, since the laser to be measured is a delicate key device, usually no external drive interface is provided to prevent damage to the laser by incorrect user operations. Therefore, the products that can be tested by such pulsed light peak power measurement devices are limited and the compatibility is low.

[0005] Alternatively, some manufacturers design pulsed light peak power measurement devices that require the drive module of the pulsed light to be measured to provide signals such as synchronous pulse clocks to the device. However, the pulsed light device to be measured 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 holding circuit to sample the input pulsed light to adjust the peak power of the laser pulsed light. This peak holding 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 holding 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 holding 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 holding 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 long-distance transmission applications, such as 20km / 40km fiber optic communication scenarios, these devices require the supply of driving electrical signals and are only suitable for measuring back-to-back pulsed light. They cannot detect the peak power of the pulsed light at the remote end.

[0008] In summary, there is an urgent need for a new pulse light peak power measurement device that can support the detection of pulse light peak power after long-distance transmission. It does not require the pulse light module to be tested to provide a corresponding clock signal or the pulse light peak power meter to provide a driving signal to the pulse light device to be tested. It has no strict restrictions on the frequency of the input pulse light to be tested, is flexibly compatible with the pulse light to be tested, and can dynamically refresh the pulse peak change to reflect the peak amplitude. Summary of the invention

[0009] In order to solve the above problems, the present invention provides a pulse light peak power measurement circuit, device and measurement method. The measurement device has the function of extracting the pulse light periodic signal and synchronizing the clock. There is no strict restriction on the frequency of the input pulse light to be measured, and the peak power of the pulse light can be accurately sampled. As long as the pulse light to be measured is injected into the optical input interface of the measurement circuit, the peak power of the pulse light can be reported.

[0010] In a first aspect, the present invention provides a pulse light peak power measurement circuit, which comprises: Optical pulse clock signal extraction unit, sampling signal generation unit, trigger signal generation unit and optical power reporting unit MCU.

[0011] The optical pulse clock signal extraction unit includes a photodiode, a photodiode driving module and an operational amplifier, wherein the photodiode is connected to the pulse light injection interface, the photodiode driving module is connected to the photodiode to provide a voltage for the photodiode, and the photodiode driving module is also connected to the input end of the operational amplifier; The sampling signal generating unit comprises an edge-triggered pulse generator, a time delayer and a digital logic module, wherein the input end of the edge-triggered pulse generator and the input end of the time delayer are respectively connected to the output end of the operational amplifier, and the output end of the edge-triggered pulse generator and the output end of the time delayer are respectively connected to the input end of the digital logic module; The trigger signal generating unit comprises a frequency reducer, the input end of which is connected to the output end of the digital logic module; The input end of the optical power reporting unit MCU is connected to the output end of the frequency converter, 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, which can read and write the MCU, and the user can read the reported value of the pulse light peak power.

[0012] 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.

[0013] In a third aspect, the present invention further provides a method for measuring the peak power of pulsed light using the aforementioned measurement device, and the method includes: Extracting the clock signal carried by the periodic optical pulse through the measurement circuit; 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 relatively, and is located at a position where the power of the optical pulse 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, which may cause abnormal operation of the MCU; When the MCU receives the trigger signal, sampling the amplitude of the optical pulse and converting the sampling result into an optical power value.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 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 peak power of the pulsed light 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.

[0015] 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. The receiving sensitivity can also be improved by enhancing the performance of the photodiode to support longer-distance optical fiber transmission.

[0016] The measurement device provided by the present invention has a function of filtering stray light pulses, low noise, and high measurement accuracy.

[0017] 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

[0018] Figure 1 is a circuit schematic diagram of the optical pulse clock signal extraction unit in the present invention; Figure 2 is a circuit schematic diagram of the sampling signal generation unit in the present invention; Figure 3 It is a circuit schematic diagram of the trigger signal generation unit in the present invention; Figure 4 It is a circuit schematic diagram of the MCU of the optical power reporting unit in the present invention; Figure 5 It is a principle block diagram of the measuring device in the present invention; Figure 6 It is a test connection schematic diagram of the measuring device in the present invention; Figure 7 is Figure 5 the timing diagram of the corresponding node; Figure 8 It is the test data of the peak optical power of the pulsed light.

[0019] 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

[0020] 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.

[0021] 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 present 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.

[0022] 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.

[0023] As Figure 1 shown, the optical pulse clock signal extraction unit includes a photodiode 1, a photodiode drive module 2, and an operational amplifier 3. The photodiode 1 is connected to the pulsed light injection interface. The photodiode drive module 2 is connected to the photodiode 1 to provide voltage for the photodiode 1, and the photodiode drive module 2 is also connected to the input terminal of the operational amplifier 3.

[0024] As Figure 2As 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 ends of the edge-triggered pulse generator 4 and the delay unit 5 are respectively connected to the output end of the operational amplifier 3, and the output ends of the edge-triggered pulse generator 4 and the delay unit 5 are respectively connected to the input ends of the digital logic module 6.

[0025] As Figure 3 shown in the figure, the trigger signal generation unit includes a frequency divider 7, and the input end of the frequency divider 7 is connected to the output end of the digital logic module 6.

[0026] As Figure 4 shown in the figure, the input end of the optical power reporting unit MCU8 is connected to the output end of the frequency divider 7, and the output end 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, and the user can read the reported value of the peak power of the pulsed light.

[0027] The measurement circuit further includes a power supply positive voltage interface VCC and a power supply ground interface GND, which provide a power input port for the normal operation of the measurement circuit.

[0028] 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, and 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 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, and the operational amplifier 3 shapes the voltage signal V_OpSig and extracts the pulsed light clock signal PulseSig.

[0029] The clock signal PulseSig enters the sampling signal generation unit. A part of it is input 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, so that the edge of the signal lags 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 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 light current signal I_OpSig.

[0030] The sampling signal SampleGen passes through the downconverter 7 of the trigger signal generation unit, and its frequency is reduced to generate the trigger signal TriggerOUT.

[0031] 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 quantifies and calculates the sampling result according to the algorithm inside the MCU8; the user reads the pulsed optical peak power reported by the MCU8 through the I2C interface.

[0032] 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 optical peak power test.

[0033] The present invention also provides a pulsed optical peak power measuring device, the principle block diagram of which is as Figure 5 shown, and the test connection schematic diagram is as Figure 6 shown. The measuring device includes the measuring circuit mentioned above, and also includes a power supply, a pulsed optical 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 measuring circuit; the pulsed optical to be measured is injected into the pulsed optical injection interface of the measuring circuit; the I2C interface of the measuring circuit establishes a communication link with the computer through an I2C to USB connector, and the computer obtains the pulsed optical peak power reported by the MCU8 through this link.

[0034] The present invention also discloses a method for measuring the pulsed optical peak power using the above-mentioned measuring device, and the measuring method includes the following steps: After the pulsed optical to be measured is injected into the measuring circuit, the clock signal carried by the periodic optical pulse is extracted through the measuring circuit; A sampling signal is generated through the clock signal, so that the edge of the sampling signal lags behind the rising edge of the optical pulse relatively and is located at a position where the optical pulse power is relatively stable; Reduce the frequency of the sampling signal, generate a trigger signal and send it to the MCU8 to avoid frequent and excessive triggering of the MCU8 interrupt, which may cause abnormal operation of the MCU8; When the MCU8 receives the trigger signal, it samples the optical pulse amplitude and converts the sampling result into an optical power value.

[0035] Figure 7 For Figure 5The timing diagram of the corresponding nodes in the shown principle block diagram. 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 is shaped by the optical pulse clock signal extraction unit and the clock is extracted to output the pulsed optical clock signal PulseSig, which 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. And another signal passes through the delay unit 5, adding a time delay of tPD to PulseSig, so that the rising edge of PulseSigDelay is after the falling edge of PulseGen. In this way, 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 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 the rising edge of TriggerOUT is detected 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 pulsed optical peak power at this time.

[0036] In the method for measuring the pulsed optical peak power, when the MCU8 receives the trigger signal, it samples the amplitude of the optical pulse to obtain the optical pulse amplitude ADCvalue at this time, and substitutes this ADCvalue into the fitting coefficient, such as linear fitting, y[mW]=f(ADCvalue)=k×ADCvalue+b to convert it into the optical power value.

[0037] Linear fitting, polynomial fitting or other fitting methods are selected according to the reporting accuracy and repeatability requirements of the pulsed optical peak power. Continuous light injection with known optical power, such as P0, P1, P2,...... as Y, and the ADCvalue0, ADCvalue1, ADCvalue2...... obtained by MCU sampling respectively as X are used for multi-point fitting, and the fitting coefficient is obtained according to the selected fitting method. This technology is the prior art and will not be elaborated here.

[0038] The measurement device of the present invention is tested by injecting a pulsed optical signal with a known peak optical power. The test data of the peak optical power of the pulsed light is as Figure 8 shown. The "actual peak pulsed optical power" is a pulsed optical signal with a known peak optical power. In the test, pulsed optical signals with pulse widths of 5 us / 10 us / 20 us and periods of 100 us / 796 us 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 test results are repeatable within ±0.2 dB and accurate within ±0.8 dB. It should be noted that the repeatability and accuracy can be improved by replacing the MCU8 with a higher-performance one, such as an ADC with a higher bit number, or optimizing the algorithm.

[0039] The measurement device provided by the present invention can adapt to the pulsed optical signal to be measured through the measurement circuit. Only the pulsed optical signal to be measured needs to be input, and there is no need to additionally output an electrical signal to drive the pulsed optical signal laser. The pulsed optical device to be measured also does not need to provide a synchronous pulse clock output interface, and the peak power of the pulsed light can be tested.

[0040] The present invention has no strict limitation on the frequency of the pulsed optical signal to be measured, is flexible in testing, has strong compatibility, and can support the measurement of the peak power of the pulsed light after 20 km / 40 km long-distance optical fiber transmission. The receiving sensitivity can also be improved by enhancing the performance of the photodiode, thereby supporting longer-distance optical fiber transmission.

[0041] The measurement 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.

[0042] 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 deformations and improvements can be made, and these all belong to 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 and can read and write 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, characterized in that, 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 measurement 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 to improve the sampling accuracy. Another part adds a time delay to the clock signal PulseSig through a delay unit, 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 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 measurement circuit according to claim 3, characterized in that, The sampling signal SampleGen passes through the frequency divider of the trigger signal generation unit, and the frequency is reduced to generate a trigger signal TriggerOUT.

5. The measurement 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 measurement circuit according to claim 6, characterized in that, The measurement circuit further includes a power supply positive voltage interface VCC and a power supply ground interface GND, which provide a power input port for the normal operation of the measurement circuit.

8. Pulse 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, a 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. 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 relatively stable position of the optical pulse power; 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; When the MCU receives the trigger signal, it samples the optical pulse amplitude and converts the sampling result into an optical power value.

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