Laser driving current control circuit

Abstract

The invention provides a laser driving current control circuit, which relates to the technical field of quantum communication, and is characterized in that driving current of a laser is acquired through an IBias sampling module, and light current generated by the laser through a photodiode is acquired through a light current sampling module; and then the feedback control module controls the output voltage of the power supply voltage stabilizing module according to the driving current of the laser and the light current generated by the photodiode. According to the laser driving current control circuit provided by the invention, through multi-source data fusion, rapid and accurate adjustment of the driving current of the laser is realized, so that the driving current is kept in a reasonable threshold range, the laser is protected, stable light intensity output by the laser is ensured, and the quality of a random number sequence generated by QRNG is further improved.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication technology, and in particular to a laser driving current control circuit. Background Art

[0002] As an important basic resource, random numbers are widely used in encryption and security, simulation and modeling, financial transactions, and communications. Among them, random number sequences are generated by quantum random number generators.

[0003] In a quantum random number generator (QRNG), lasers are an important light source component. In existing technologies, the light source is affected by factors such as the laser's own imperfections and temperature, and the output light intensity fluctuates, which affects the estimation of the minimum entropy, resulting in a decrease in the randomness of the output random numbers and a potential safety hazard. Summary of the invention

[0004] The present invention provides a laser driving current control circuit to solve the problem in the prior art that the output light intensity of the laser is unstable due to the imperfection of its own device or the influence of factors such as temperature, thereby affecting the estimation of minimum entropy and resulting in low quality of the random number sequence generated by QRNG.

[0005] The present invention provides a laser driving current control circuit, comprising: a power supply voltage stabilization module, an I_Bias sampling module, a photocurrent sampling module and a feedback control module; The first input end of the power supply voltage stabilizing module is connected to the output end of the internal power supply module, the second input end of the power supply voltage stabilizing module is connected to the output end of the feedback control module, the output end of the power supply voltage stabilizing module is connected to the input end of the I_Bias sampling module, and the power supply voltage stabilizing module is used to provide a stable voltage for the laser; The first output end of the I_Bias sampling module is connected to the first input end of the feedback control module, the laser signal generated by the I_Bias sampling module is received by the photocurrent sampling module, and the I_Bias sampling module is used to collect the driving current of the laser and generate a laser signal under the driving of the driving current; The first output end of the photocurrent sampling module is connected to the second input end of the feedback control module, the second output end of the photocurrent sampling module is connected to the third input end of the feedback control module, and the photocurrent sampling module is used to collect the photocurrent generated by the laser through the photodiode; The feedback control module is used to control the output voltage of the power supply voltage stabilizing module according to the driving current of the laser collected by the I_Bias sampling module and the photocurrent generated by the laser through the photodiode collected by the photocurrent sampling module.

[0006] According to a laser driving current control circuit provided by the present invention, the power supply voltage stabilization module includes a voltage stabilizer, a first resistor and a second resistor; The input pin of the voltage regulator is connected to the output end of the internal power module, the ground pin of the voltage regulator is grounded, the output pin of the voltage regulator is connected to the input end of the I_Bias sampling module, and the adjustment pin of the voltage regulator is connected to the output end of the feedback control module; A first end of the first resistor is connected to an output pin of the voltage regulator, and a second end of the first resistor is connected to an adjustment pin of the voltage regulator; The first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is grounded.

[0007] According to a laser driving current control circuit provided by the present invention, the I_Bias sampling module includes a third resistor, a first operational amplifier and a laser; The first end of the third resistor is connected to the output end of the power supply voltage stabilizing module, and the second end of the third resistor is connected to the input end of the laser; The first input terminal of the first operational amplifier is connected to the first terminal of the third resistor, the second input terminal of the first operational amplifier is connected to the second terminal of the third resistor, and the output terminal of the first operational amplifier is connected to the first input terminal of the feedback control module; The laser is used to generate a laser signal.

[0008] According to a laser driving current control circuit provided by the present invention, a beam splitter is further included between the I_Bias sampling module and the photocurrent sampling module; The beam splitter is used to receive the laser signal generated by the I_Bias sampling module and convert the laser signal into a first light beam and a second light beam, and the power of the first light beam and the power of the second light beam are the same.

[0009] According to a laser driving current control circuit provided by the present invention, the photocurrent sampling module includes a fourth resistor, a first photodiode, a second photodiode, a fifth resistor, a transimpedance amplifier, a second operational amplifier, a third operational amplifier and a fourth operational amplifier; The first end of the fourth resistor is connected to the first input end of the second operational amplifier, and the second end of the fourth resistor is connected to the second input end of the second operational amplifier; The first end of the first photodiode is connected to the second end of the fourth resistor, and the second end of the first photodiode is connected to the input end of the transimpedance amplifier; The first end of the second photodiode is connected to the second end of the first photodiode, and the second end of the second photodiode is connected to the first end of the fifth resistor; The first end of the fifth resistor is connected to the first input end of the third operational amplifier, and the second end of the fifth resistor is connected to the second input end of the third operational amplifier; The output terminal of the transimpedance amplifier is connected to the first input terminal of the fourth operational amplifier; The output terminal of the second operational amplifier is connected to the second input terminal of the feedback control module; The output terminal of the third operational amplifier is connected to the third input terminal of the feedback control module; The second input terminal of the fourth operational amplifier is grounded.

[0010] According to a laser driving current control circuit provided by the present invention, the first photodiode is used to receive the first light beam and convert the first light beam into a first electrical signal.

[0011] According to a laser driving current control circuit provided by the present invention, the second photodiode is used to receive the second light beam and convert the second light beam into a second electrical signal.

[0012] According to a laser driving current control circuit provided by the present invention, the output end of the fourth operational amplifier is a voltage test end, and the voltage test end is used to test the difference between a first voltage across the first photodiode and a second voltage across the second photodiode.

[0013] According to a laser driving current control circuit provided by the present invention, the feedback control module includes an analog-to-digital conversion module and a micro control unit; The first end of the analog-to-digital conversion module is connected to the first output end of the I_Bias sampling module, the second end of the analog-to-digital conversion module is connected to the first output end of the photocurrent sampling module, the third end of the analog-to-digital conversion module is connected to the second output end of the photocurrent sampling module, the fourth end of the analog-to-digital conversion module is grounded, the fifth end of the analog-to-digital conversion module is connected to the first end of the micro control unit, and the sixth end of the analog-to-digital conversion module is connected to the second end of the micro control unit; The third terminal of the micro control unit is connected to the second input terminal of the power supply voltage stabilization module.

[0014] The present invention also provides a quantum random number generator, comprising any one of the laser driving current control circuits.

[0015] The present invention provides a laser driving current control circuit, which collects the driving current of the laser through an I_Bias sampling module, collects the photocurrent generated by the laser through a photodiode through a photocurrent sampling module, and then controls the output voltage of a power supply voltage stabilizing module according to the driving current of the laser and the photocurrent generated by the laser through the photodiode through a feedback control module, thereby realizing fast and accurate adjustment of the driving current of the laser through multi-source data fusion, keeping the driving current within a reasonable threshold range, ensuring stable output light intensity while protecting the laser, solving the problem of fluctuation in output light intensity caused by factors such as imperfection of the laser device itself or temperature, and thus improving the quality of the random number sequence generated by QRNG. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 The present invention provides a laser driving current control circuit.

[0018] Figure 2 The present invention provides a circuit structure diagram of a laser driving current control circuit.

[0019] Figure 3 The present invention provides a circuit structure schematic diagram of an external resistor between an adjustment pin ADJ of a voltage regulator and a feedback control module.

[0020] Figure 4 It is a schematic diagram of a flow chart of multi-source data fusion in a laser driving current control circuit provided by the present invention. DETAILED DESCRIPTION

[0021] As an important basic resource, random numbers are widely used in encryption and security, simulation and modeling, financial transactions, communications and other fields. According to the different characteristics of random numbers, they can be divided into pseudo-random numbers and true random numbers. Pseudo-random numbers are often calculated by a specific algorithm with a set seed and are predictable. Therefore, pseudo-random numbers cannot be used in fields with high randomness requirements (such as encryption algorithms, quantum communications, etc.). True random numbers are unpredictable, statistically uniform and non-repeatable, and play an important role in the application field of random numbers. Therefore, it is of great significance to explore how to generate true random number sequences.

[0022] A random number generator is a device used to generate a random number sequence. Random number generators are divided into pseudo-random number generators and physical random number generators. Current research believes that the quantum random number generator in the physical random number generator is a device that generates true random numbers. QRNG is based on the principles of quantum mechanics, and its randomness comes from the uncertainty of the quantum world.

[0023] In most QRNG implementations, lasers are important components. In the prior art, the laser light source in QRNG uses a constant current power supply. However, due to the imperfection of the device itself, temperature and other external factors, the light intensity output by the light source will fluctuate, making it impossible to accurately estimate the minimum entropy, which in turn leads to a decrease in the randomness of the output random numbers, reducing the quality of the generated random number sequence, affecting the overall performance of QRNG, and creating safety risks.

[0024] In response to the above problems, the present invention proposes a technical solution to stabilize the optical power of the laser by fusing multi-source data. Specifically, feedback control is performed by measuring the current value of the photodiode to adjust the driving current of the light source; at the same time, the driving current of the light source is measured to keep the current within a reasonable threshold range, thereby ensuring the normal operation of the laser. The technical solution of the present invention combines the photodiode current data and the laser light source driving current data, which can protect the laser light source of the QRNG and stabilize its output, thereby improving the randomness of the output random number sequence.

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Combine the following Figures 1 to 4 A laser driving current control circuit of the present invention is described.

[0027] Figure 1 is an overall block diagram of a laser driving current control circuit provided by the present invention, such as Figure 1 As shown, the circuit at least includes: a power supply voltage stabilization module, an I_Bias sampling module, a photocurrent sampling module and a feedback control module.

[0028] The first input end of the power supply voltage stabilizing module is connected to the output end of the internal power supply module, the second input end of the power supply voltage stabilizing module is connected to the output end of the feedback control module, the output end of the power supply voltage stabilizing module is connected to the input end of the I_Bias sampling module, and the power supply voltage stabilizing module is used to provide a stable voltage for the laser; The first output end of the I_Bias sampling module is connected to the first input end of the feedback control module, the laser signal generated by the I_Bias sampling module is received by the photocurrent sampling module, and the I_Bias sampling module is used to collect the driving current of the laser and generate a laser signal under the driving of the driving current; The first output end of the photocurrent sampling module is connected to the second input end of the feedback control module, the second output end of the photocurrent sampling module is connected to the third input end of the feedback control module, and the photocurrent sampling module is used to collect the photocurrent generated by the laser through the photodiode; The feedback control module is used to control the output voltage of the power supply voltage stabilizing module according to the driving current of the laser collected by the I_Bias sampling module and the photocurrent generated by the laser through the photodiode collected by the photocurrent sampling module.

[0029] Specifically, the laser driving current control circuit provided by the present invention at least includes: a power supply voltage stabilization module, an I_Bias sampling module, a photocurrent sampling module and a feedback control module.

[0030] The first input end of the power supply voltage regulator module is connected to the output end of the internal power supply module, the second input end of the power supply voltage regulator module is connected to the output end of the feedback control module, the output end of the power supply voltage regulator module is connected to the input end of the I_Bias sampling module, and the power supply voltage regulator module is used to provide a stable voltage for the laser; The first output end of the I_Bias sampling module is connected to the first input end of the feedback control module, and the laser signal generated by the I_Bias sampling module is received by the photocurrent sampling module. The I_Bias sampling module is used to collect the driving current of the laser and generate a laser signal under the driving of the driving current; The first output end of the photocurrent sampling module is connected to the second input end of the feedback control module, the second output end of the photocurrent sampling module is connected to the third input end of the feedback control module, and the photocurrent sampling module is used to collect the photocurrent generated by the laser through the photodiode; The feedback control module is used to control the output voltage of the power supply voltage stabilizing module according to the driving current of the laser collected by the I_Bias sampling module and the photocurrent generated by the laser through the photodiode collected by the photocurrent sampling module.

[0031] The laser driving current control circuit provided by the present invention first collects the driving current of the laser through an I_Bias sampling module, collects the photocurrent generated by the laser through a photodiode through a photocurrent sampling module, and then controls the output voltage of the power supply voltage stabilizing module according to the driving current of the laser and the photocurrent generated by the laser through the photodiode through a feedback control module, thereby being able to quickly adjust the driving current of the laser to keep the driving current within a reasonable threshold range, protecting the laser and making its output optical power constant, solving the problem of unstable output light intensity caused by factors such as the imperfection of the laser device itself or temperature, and thus improving the quality of the random number sequence generated by the QRNG.

[0032] Figure 2 Schematic diagram of the circuit structure of a laser driving current control circuit provided by the present invention, such as Figure 2 shown.

[0033] Optionally, the power supply voltage stabilization module includes a voltage stabilizer, a first resistor and a second resistor; The input pin of the voltage regulator is connected to the output end of the internal power module, the ground pin of the voltage regulator is grounded, the output pin of the voltage regulator is connected to the input end of the I_Bias sampling module, and the adjustment pin of the voltage regulator is connected to the output end of the feedback control module; A first end of the first resistor is connected to an output pin of the voltage regulator, and a second end of the first resistor is connected to an adjustment pin of the voltage regulator; The first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is grounded.

[0034] Specifically, the input pin of the voltage regulator 202 is connected to the output end of the internal power module 201, the ground pin GND of the voltage regulator 202 is grounded, the output pin VOUT of the voltage regulator 202 is connected to the input end of the I_Bias sampling module, and the adjustment pin ADJ of the voltage regulator 202 is connected to the output end of the feedback control module.

[0035] A first end of the first resistor 203 is connected to the output pin VOUT of the voltage regulator 201 , and a second end of the first resistor 203 is connected to the adjustment pin ADJ of the voltage regulator 201 ; A first end of the second resistor 204 is connected to a second end of the first resistor 203 , and a second end of the second resistor 204 is grounded.

[0036] In the embodiment of the present invention, the internal power module 201 may be a battery or other power supply device, which is used to supply power to the power stabilizing module.

[0037] The voltage regulator 202 may be a low dropout linear regulator (LDO), which is a 5-pin chip. Its main function is to stably convert a higher input voltage into a lower output voltage, and to maintain a stable output voltage when the input voltage drops. The voltage regulator 202 includes: Input pin VIN, used to connect input power; Ground pin GND, used to connect the circuit ground; Output pin VOUT, used to connect output load; An adjustment pin ADJ, used for dividing the voltage through the first resistor 203 and the second resistor 204, thereby adjusting the output voltage; The enable pin EN is used to control the switching state of the regulator 202 .

[0038] In some embodiments, the voltage can also be adjusted by connecting an external resistor between the adjustment pin ADJ of the voltage regulator 202 and the feedback control module. Figure 3 : is a circuit structure diagram of an external resistor between an adjustment pin ADJ of a voltage regulator and a feedback control module provided by the present invention, such as Figure 3 On the basis of the voltage division of the first resistor 203 and the second resistor 204, the output voltage of the power supply voltage regulator module can be adjusted more accurately by further dividing the voltage through an external resistor.

[0039] The power supply voltage regulator module can provide a stable voltage for the laser and realize fast and accurate regulation of the laser's driving current, so that the driving current remains within a reasonable threshold range, thus protecting the laser and ensuring its stable output light intensity.

[0040] Optionally, the I_Bias sampling module includes a third resistor, a first operational amplifier and a laser; The first end of the third resistor is connected to the output end of the power supply voltage stabilizing module, and the second end of the third resistor is connected to the input end of the laser; The first input terminal of the first operational amplifier is connected to the first terminal of the third resistor, the second input terminal of the first operational amplifier is connected to the second terminal of the third resistor, and the output terminal of the first operational amplifier is connected to the first input terminal of the feedback control module; The laser is used to generate a laser signal.

[0041] Specifically, the I_Bias sampling module includes a third resistor 205, a first operational amplifier 206 and a laser 207; A first end of the third resistor 205 is connected to the output end of the power supply voltage stabilizing module, and a second end of the third resistor 205 is connected to the input end of the laser 207; A first input terminal of the first operational amplifier 206 is connected to a first terminal of the third resistor 205, a second input terminal of the first operational amplifier 206 is connected to a second terminal of the third resistor 205, and an output terminal of the first operational amplifier 206 is connected to a first input terminal of the feedback control module; The laser 207 is a local oscillator light source device for homodyne detection, and is used to generate a laser signal. In the embodiment of the invention, the laser 207 is described by taking a laser diode (LD) as an example.

[0042] The I_Bias sampling module provided by the present invention amplifies the voltage across the third resistor 205 through the first operational amplifier 206, and outputs the amplified voltage signal. The output monitoring 208 is used to represent the amplified voltage signal, which is output to the feedback control module. Combined with the resistance value of the third resistor 205, the current value flowing through the third resistor 205, that is, the driving current of the laser, can be calculated according to Ampere's law, thereby providing a basis for subsequent adjustment of the driving current of the laser.

[0043] Optionally, a beam splitter is further included between the I_Bias sampling module and the photocurrent sampling module; The beam splitter is used to receive the laser signal generated by the I_Bias sampling module and convert the laser signal into a first light beam and a second light beam, and the power of the first light beam and the power of the second light beam are the same.

[0044] Specifically, a beam splitter is also included between the I_Bias sampling module and the photocurrent sampling module; The beam splitter is used to receive the laser signal generated by the I_Bias sampling module and convert the laser signal into a first light beam and a second light beam, and the power of the first light beam and the second light beam are the same.

[0045] In the I_Bias sampling module, the initial state in the beam splitter 209 is the Vacuum state, which is a system-independent state and does not require preparation. When the laser 207 emits the local oscillator light of homodyne detection, the random signal in the vacuum state of the beam splitter 209 can be amplified. At this time, the laser signal generated by the laser 207 is received by the beam splitter 209, and the laser signal interferes with the random signal in the vacuum state of the beam splitter 209 to form two output beams with balanced power, namely the first beam and the second beam.

[0046] Among them, the beam splitter 209 is an optical device that can split a beam of light into two beams or multiple beams of light. In the embodiment of the present invention, the beam splitter 209 that splits a beam of light into two beams of light (i.e., a first beam and a second beam) is taken as an example for explanation. The power of the first beam and the second beam is the same, and the sum of the power of the first beam and the second beam is equal to the light intensity power generated by the laser.

[0047] In the embodiment of the present invention, the first light beam and the second light beam emitted from the beam splitter 209 are respectively incident on two photodiodes (ie, the first photodiode 210 and the second photodiode 211 ) with the same performance in the photocurrent sampling module, providing a basis for subsequent photocurrent collection.

[0048] At the same time, since the power of the first light beam and the second light beam is the same, it is convenient to compare and verify the two photocurrent sampling signals and perform photodiode fault troubleshooting. For example, when one signal suddenly changes while the other is normal, and the I_Bias sampling module works normally, it can be determined that the photodiode with the sudden signal change is faulty and should be checked and replaced in time, thereby providing monitoring and protection for the working status of the circuit.

[0049] Optionally, the photocurrent sampling module includes a fourth resistor, a first photodiode, a second photodiode, a fifth resistor, a transimpedance amplifier, a second operational amplifier, a third operational amplifier and a fourth operational amplifier; The first end of the fourth resistor is connected to the first input end of the second operational amplifier, and the second end of the fourth resistor is connected to the second input end of the second operational amplifier; The first end of the first photodiode is connected to the second end of the fourth resistor, and the second end of the first photodiode is connected to the input end of the transimpedance amplifier; The first end of the second photodiode is connected to the second end of the first photodiode, and the second end of the second photodiode is connected to the first end of the fifth resistor; The first end of the fifth resistor is connected to the first input end of the third operational amplifier, and the second end of the fifth resistor is connected to the second input end of the third operational amplifier; The output terminal of the transimpedance amplifier is connected to the first input terminal of the fourth operational amplifier; The output terminal of the second operational amplifier is connected to the second input terminal of the feedback control module; The output terminal of the third operational amplifier is connected to the third input terminal of the feedback control module; The second input terminal of the fourth operational amplifier is grounded.

[0050] Specifically, the photocurrent sampling module includes a fourth resistor 218, a first photodiode 210, a second photodiode 211, a fifth resistor 219, a transimpedance amplifier 215, a second operational amplifier 212, a third operational amplifier 213 and a fourth operational amplifier 216; A first end of the fourth resistor 218 is connected to the first input end of the second operational amplifier 212 , and a second end of the fourth resistor 218 is connected to the second input end of the second operational amplifier 212 ; The first end of the first photodiode 210 is connected to the second end of the fourth resistor 218 , and the second end of the first photodiode 210 is connected to the input end of the transimpedance amplifier 215 ; A first end of the second photodiode 211 is connected to a second end of the first photodiode 210 , and a second end of the second photodiode 211 is connected to a first end of the fifth resistor 219 ; A first end of the fifth resistor 219 is connected to a first input end of the third operational amplifier 213 , and a second end of the fifth resistor 219 is connected to a second input end of the third operational amplifier 213 ; The output end of the transimpedance amplifier 215 is connected to the first input end of the fourth operational amplifier 216, and is used to convert the photocurrent generated by the first photodiode 210 and the second photodiode 211 into a certain proportion of the output voltage, so as to timely check whether the first photodiode 210 and the second photodiode 211 are faulty by measuring the voltage, thereby ensuring the normal operation of the circuit.

[0051] The output terminal of the second operational amplifier 212 is connected to the second input terminal of the feedback control module; The output terminal of the third operational amplifier 213 is connected to the third input terminal of the feedback control module; A second input terminal of the fourth operational amplifier 216 is grounded.

[0052] In the embodiment of the present invention, two light beams with the same power emitted by the beam splitter are converted into electrical signals (or photocurrents) by two photodiodes with the same performance (a first photodiode 210 and a second photodiode 211), and the voltage is divided by a fourth resistor 218 and a fifth resistor 219. Then, the voltage across the fourth resistor 218 is amplified by a second operational amplifier 212, and the voltage across the fifth resistor 219 is amplified by a third operational amplifier 213.

[0053] In the photocurrent sampling module, the first single-channel output monitoring 214 represents the voltage across the fourth resistor 218, and the second single-channel output monitoring 217 represents the voltage across the fifth resistor 219. Both voltages are output to the feedback control module. The average value of the two voltages is proportional to the photocurrent generated by the photodiode. The photocurrent value can be calculated according to Ampere's law, thereby providing a basis for adjusting the driving current of the laser.

[0054] Optionally, the first photodiode is used to receive the first light beam and convert the first light beam into a first electrical signal.

[0055] Optionally, the second photodiode is used to receive the second light beam and convert the second light beam into a second electrical signal.

[0056] Specifically, the first photodiode 210 is used to receive a first light beam and convert the first light beam into a first electrical signal.

[0057] The second photodiode 211 is used to receive the second light beam and convert the second light beam into a second electrical signal.

[0058] In the embodiment of the present invention, a photodiode is used to convert the laser signal generated by the laser 207 into an electrical signal to generate a photocurrent, thereby determining whether the driving current of the laser is normal by testing the photocurrent, and providing a basis for the feedback control module to adjust the driving current.

[0059] The photodiode (PD) can be a variety of diodes such as a PN junction photodiode or a PIN photodiode, but two photodiodes with the same performance are preferred so that when troubleshooting the photodiode, comparative verification can be performed, thereby reducing the difficulty of circuit maintenance.

[0060] Optionally, the output end of the fourth operational amplifier is a voltage test end, and the voltage test end is used to test the difference between a first voltage across the first photodiode and a second voltage across the second photodiode.

[0061] Specifically, the output terminal of the fourth operational amplifier 216 is a voltage test terminal, and the voltage test terminal is used to test the difference between the first voltage across the first photodiode 210 and the second voltage across the second photodiode 211 .

[0062] The current flowing through the first photodiode 210 is converted into a first voltage through the transimpedance amplifier 215, and the current flowing through the second photodiode 211 is converted into a second voltage, and then the difference between the first voltage and the second voltage (the difference here is an absolute value) is calculated and output, and then the difference output by the transimpedance amplifier 215 is amplified by the fourth operational amplifier 216, so that the difference is measured by a voltage detector (such as a pressure gauge or a voltage detector, etc.), and it is determined whether the difference is within a normal range. If so, both photodiodes are working normally; if not, it means that one or both of the two photodiodes are faulty. In this case, it is necessary to further detect the voltage signals of the first single-channel output monitor 214 and the second single-channel output monitor 217, and compare and verify the two voltage signals, so as to quickly troubleshoot the photodiodes.

[0063] For example, when the voltage signal of the first single-channel output monitor 214 changes suddenly while the voltage signal of the second single-channel output monitor 217 is normal and the I_Bias sampling module works normally, it means that the first photodiode 210 is faulty and should be checked and replaced in time.

[0064] For another example, when the voltage signals of the first single-channel output monitor 214 and the second single-channel output monitor 217 both change suddenly, it means that both the first photodiode 210 and the second photodiode 211 fail and should be checked and replaced in time.

[0065] The embodiment of the present invention tests the difference between the first voltage at both ends of the first photodiode 210 and the second voltage at both ends of the second photodiode 211 through the voltage test end, so as to realize real-time monitoring of the first photodiode 210 and the second photodiode 211, detect faults early, and thus ensure the normal operation of the circuit.

[0066] Optionally, the feedback control module includes an analog-to-digital conversion module and a micro control unit; The first end of the analog-to-digital conversion module is connected to the first output end of the I_Bias sampling module, the second end of the analog-to-digital conversion module is connected to the first output end of the photocurrent sampling module, the third end of the analog-to-digital conversion module is connected to the second output end of the photocurrent sampling module, the fourth end of the analog-to-digital conversion module is grounded, the fifth end of the analog-to-digital conversion module is connected to the first end of the micro control unit, and the sixth end of the analog-to-digital conversion module is connected to the second end of the micro control unit; The third terminal of the micro control unit is connected to the second input terminal of the power supply voltage stabilization module.

[0067] Specifically, the feedback control module includes an analog-to-digital conversion module 220 and a micro control unit 221 .

[0068] In the embodiment of the present invention, the analog-to-digital conversion module 220 is an analog-to-digital converter, and the embodiment of the present invention is described by taking an analog-to-digital converter of an 8-pin chip as an example. The microcontroller unit (MCU) 221 can be an 8-bit, 16-bit or 32-bit single-chip microcomputer, and the embodiment of the present invention is described by taking an 8-bit STM32 single-chip microcomputer as an example.

[0069] The first end (analog signal input pin AIN0) of the analog-to-digital conversion module 220 is connected to the first output end (output monitoring 208) of the I_Bias sampling module to receive the amplified voltage signal of the voltage across the third resistor 205, thereby calculating the driving current of the laser.

[0070] The second end (analog signal input pin AIN1) of the analog-to-digital conversion module 220 is connected to the first output end of the photocurrent sampling module, and the third end (analog signal input pin AIN2) of the analog-to-digital conversion module 220 is connected to the second output end of the photocurrent sampling module, respectively used to receive two voltage signals and calculate the photocurrent value flowing through the photodiode according to Ampere's law.

[0071] A fourth terminal (ground pin GND) of the analog-to-digital conversion module 220 is grounded.

[0072] The fifth end (synchronous serial data communication pin SDA) of the analog-to-digital conversion module 220 is connected to the first end (IIC serial data interface SDA) of the microcontroller unit, and the sixth end (clock communication pin SCL) of the analog-to-digital conversion module 220 is connected to the second end (IIC serial clock interface SCL) of the microcontroller unit. The fifth and sixth ends of the analog-to-digital conversion module 220 are used to convert analog signals (laser driving current and photocurrent flowing through the photodiode) into digital signals and transmit them to the microcontroller unit, thereby providing a basis for adjusting the output voltage of the power supply voltage regulator module.

[0073] The seventh terminal (positive power supply pin VDD) of the analog-to-digital conversion module 220 is used to connect the positive voltage input, and the eighth terminal (analog signal input pin AIN3) of the analog-to-digital conversion module 220 can be selected for use when more analog signals need to be collected.

[0074] The third end (DAC OUT interface) of the microcontroller unit 221 is connected to the second input end of the power regulator module (i.e., the adjustment pin ADJ of the regulator 202). The third end of the microcontroller unit 221 is used to convert the digital signal into an analog voltage output, thereby controlling the output voltage of the power regulator module through the adjustment pin ADJ of the regulator 202, and further adjusting the driving current of the laser to keep the driving current within a reasonable threshold range, thereby protecting the laser while ensuring its output of stable light intensity.

[0075] Optionally, an embodiment of the present invention further provides a quantum random number generator, comprising the laser driving current control circuit described in any of the above embodiments.

[0076] Specifically, the structure and working principle of the laser driving current control circuit in the above-mentioned quantum random number generator provided in the embodiment of the present invention can refer to the above-mentioned embodiment, and can achieve the same technical effect. The same parts and beneficial effects will not be described in detail here.

[0077] Figure 4 FIG. 1 is a flow chart of multi-source data fusion in a laser driving current control circuit provided by the present invention, such as Figure 4 shown.

[0078] In the case of a specific application, based on any of the above embodiments, when the quantum random number generator is powered on at room temperature, MCU221 first sets the current threshold according to the driving current parameter of the laser 207, and calculates the current laser driving current value by recording the voltage value across the third resistor 205, and compares it with the threshold value to determine whether the driving current of the laser 207 is normal.

[0079] At the same time, MCU221 will measure the output voltage values ​​of the first single-channel output monitor 214 and the second single-channel output monitor 217, and obtain the initial value of the total photocurrent output by the first photodiode 210 and the second photodiode 211 through the average of the two voltages. Since the photocurrent is proportional to the laser output light intensity, the stability of the photocurrent means the stability of the laser output light intensity.

[0080] During operation, due to the imperfect limitations of the laser device and changes in factors such as temperature, the laser output light intensity will change or fluctuate, resulting in a change in the mean value of the voltage of the first single-channel output monitor 214 and the second single-channel output monitor 217, that is, the photocurrent changes. At this time, the difference between the changed photocurrent mean value and the initial photocurrent value is calculated, and the output voltage of the regulator 202 is adjusted through the Proportional-Integral-Differential (PID) control algorithm, thereby changing the driving current of the laser until the photocurrent output by the first single-channel output monitor 214 and the second single-channel output monitor 217 is equal to the initial value, thereby achieving stable output of the laser.

[0081] At the same time, by combining the voltage signal input by the output monitoring 208 for calculation, MCU221 can obtain the real-time driving current of the laser 207. MCU221 compares it with the laser driving current threshold in real time. When the driving current is greater than the threshold, it controls the voltage regulator 202 to limit the current, thereby protecting the laser.

[0082] The embodiment of the present invention performs PID feedback control on the laser driving current by measuring the photocurrent output by the photodiode and the laser driving current. On the one hand, the driving current that exceeds the reasonable threshold is limited to ensure the normal operation of the laser; on the other hand, a high-speed analog-to-digital converter is used for analog-to-digital conversion, combined with the PID control algorithm for control, and the driving current is quickly adjusted to ensure that the optical power output by the laser is constant. In this way, while protecting the normal operation of the laser, the fluctuation of the laser output light intensity is reduced, thereby improving the quality of the random number sequence generated by the QRNG.

[0083] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0084] It should also be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first" and "second" are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser driving current control circuit, characterized in that: include: Power supply voltage stabilization module, I_Bias sampling module, photocurrent sampling module and feedback control module; The first input end of the power supply voltage stabilizing module is connected to the output end of the internal power supply module, the second input end of the power supply voltage stabilizing module is connected to the output end of the feedback control module, the output end of the power supply voltage stabilizing module is connected to the input end of the I_Bias sampling module, and the power supply voltage stabilizing module is used to provide a stable voltage for the laser; The first output end of the I_Bias sampling module is connected to the first input end of the feedback control module, the laser signal generated by the I_Bias sampling module is received by the photocurrent sampling module, and the I_Bias sampling module is used to collect the driving current of the laser and generate a laser signal under the driving of the driving current; The first output end of the photocurrent sampling module is connected to the second input end of the feedback control module, the second output end of the photocurrent sampling module is connected to the third input end of the feedback control module, and the photocurrent sampling module is used to collect the photocurrent generated by the laser through the photodiode; The feedback control module is used to control the output voltage of the power supply voltage stabilizing module according to the driving current of the laser collected by the I_Bias sampling module and the photocurrent generated by the laser through the photodiode collected by the photocurrent sampling module.

2. The laser driving current control circuit according to claim 1, characterized in that: The power supply voltage stabilization module includes a voltage stabilizer, a first resistor and a second resistor; The input pin of the voltage regulator is connected to the output end of the internal power module, the ground pin of the voltage regulator is grounded, the output pin of the voltage regulator is connected to the input end of the I_Bias sampling module, and the adjustment pin of the voltage regulator is connected to the output end of the feedback control module; A first end of the first resistor is connected to an output pin of the voltage regulator, and a second end of the first resistor is connected to an adjustment pin of the voltage regulator; The first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is grounded.

3. The laser driving current control circuit according to claim 1, characterized in that: The I_Bias sampling module includes a third resistor, a first operational amplifier and a laser; The first end of the third resistor is connected to the output end of the power supply voltage stabilizing module, and the second end of the third resistor is connected to the input end of the laser; The first input terminal of the first operational amplifier is connected to the first terminal of the third resistor, the second input terminal of the first operational amplifier is connected to the second terminal of the third resistor, and the output terminal of the first operational amplifier is connected to the first input terminal of the feedback control module; The laser is used to generate a laser signal.

4. The laser driving current control circuit according to claim 1, characterized in that: A beam splitter is also included between the I_Bias sampling module and the photocurrent sampling module; The beam splitter is used to receive the laser signal generated by the I_Bias sampling module and convert the laser signal into a first light beam and a second light beam, and the power of the first light beam and the power of the second light beam are the same.

5. The laser driving current control circuit according to claim 1, characterized in that: The photocurrent sampling module includes a fourth resistor, a first photodiode, a second photodiode, a fifth resistor, a transimpedance amplifier, a second operational amplifier, a third operational amplifier and a fourth operational amplifier; The first end of the fourth resistor is connected to the first input end of the second operational amplifier, and the second end of the fourth resistor is connected to the second input end of the second operational amplifier; The first end of the first photodiode is connected to the second end of the fourth resistor, and the second end of the first photodiode is connected to the input end of the transimpedance amplifier; The first end of the second photodiode is connected to the second end of the first photodiode, and the second end of the second photodiode is connected to the first end of the fifth resistor; The first end of the fifth resistor is connected to the first input end of the third operational amplifier, and the second end of the fifth resistor is connected to the second input end of the third operational amplifier; The output terminal of the transimpedance amplifier is connected to the first input terminal of the fourth operational amplifier; The output terminal of the second operational amplifier is connected to the second input terminal of the feedback control module; The output terminal of the third operational amplifier is connected to the third input terminal of the feedback control module; The second input terminal of the fourth operational amplifier is grounded.

6. The laser driving current control circuit according to claim 5, characterized in that: The first photodiode is used to receive the first light beam and convert the first light beam into a first electrical signal.

7. The laser driving current control circuit according to claim 5, characterized in that: The second photodiode is used to receive the second light beam and convert the second light beam into a second electrical signal.

8. The laser driving current control circuit according to claim 5, characterized in that: The output end of the fourth operational amplifier is a voltage test end, and the voltage test end is used to test the difference between a first voltage across the first photodiode and a second voltage across the second photodiode.

9. The laser driving current control circuit according to claim 1, characterized in that: The feedback control module includes an analog-to-digital conversion module and a microcontroller unit; The first end of the analog-to-digital conversion module is connected to the first output end of the I_Bias sampling module, the second end of the analog-to-digital conversion module is connected to the first output end of the photocurrent sampling module, the third end of the analog-to-digital conversion module is connected to the second output end of the photocurrent sampling module, the fourth end of the analog-to-digital conversion module is grounded, the fifth end of the analog-to-digital conversion module is connected to the first end of the micro control unit, and the sixth end of the analog-to-digital conversion module is connected to the second end of the micro control unit; The third terminal of the micro control unit is connected to the second input terminal of the power supply voltage stabilization module.

10. A quantum random number generator, characterized in that: The laser driving current control circuit comprises the laser driving current control circuit according to any one of claims 1 to 9.

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