A system for generating high-speed physical random numbers using light phase

Abstract

The application belongs to the technical field of physical random number generators, and particularly relates to a system for generating high-speed physical random numbers by using light phase. The system comprises a light emitting unit, a polarization maintaining 2*2 optical coupler and two phase noise detection units connected in sequence. The light emitting unit comprises a light source, a polarization maintaining filter and an erbium-doped fiber amplifier connected in sequence. The erbium-doped fiber amplifier is connected with the polarization maintaining 2*2 optical coupler. The phase noise detection unit comprises a polarization maintaining 3*3 optical coupler, two Faraday rotators and two balanced photodetectors. The polarization maintaining 3*3 optical coupler divides light into two arms with different lengths. The two balanced photodetectors subtract signals to obtain an original analog signal. Then, the original analog signal is converted into a voltage signal by a digital-to-analog converter. The application extracts random numbers by using the phase noise of a spontaneous emission light source. The application does not need a long interference arm length difference and light source pump state control, and has a simple structure and is convenient and easy to implement.

Description

Technical Field

[0001] This invention belongs to the field of physical random number generation technology, specifically relating to a system for generating high-speed physical random numbers using optical phase. Background Technology

[0002] Random numbers have wide applications in computational simulation, statistical sampling, cryptography, and information security. Currently, random number generation methods are mainly divided into two categories: pseudo-random number generation methods and physical random number generation methods. Pseudo-random number generation methods use random number generation algorithms and initial seeds to generate pseudo-random numbers and are currently a widely used method. However, pseudo-random number generation methods depend on the selection of the seed, and the generation algorithm is deterministic, making this method unsuitable for fields with high requirements for randomness and security. Physical random number generation methods, on the other hand, generate random numbers by detecting random fluctuations in a physical system. The randomness is guaranteed by the real physical system, offering high security and unpredictability. A commonly used physical system is the optical system, which features fast generation speed, good randomness, and simple structure. Research on generating random numbers from the physical layer using optical methods has progressed rapidly both domestically and internationally in recent years, resulting in various products based on different principles. These can be broadly categorized into two types based on their technical principles: random number generation based on light source intensity noise and random number generation based on light source phase noise. The basic principle of random number generation based on light source intensity noise is to directly detect the intensity fluctuation signal of the light emitted by the light source. Amplified spontaneous emission (ASE) sources are commonly used, and detectors are used to directly detect the light intensity signal. However, this method has currently encountered a bottleneck in generation rate, making it difficult to modularize and improve upon. The basic principle of random number generation based on light source phase noise is to detect the phase fluctuation signal of the light emitted by the light source. Narrow-linewidth lasers are commonly used as the light source, and interferometric structures such as MZ-type or Michelson-type are used to detect phase fluctuations. This method typically requires a long difference in the length of the interferometer arms, a large volume, and control over the laser's operating state, resulting in a more complex structure.

[0003] In recent years, the rate of physical random number generation based on optical methods has been greatly improved, reaching the Gbps level. However, to further meet the current demands of high-speed, high-capacity communication or high-speed computational simulation, even higher random number generation rates and more convenient configurations are required. Therefore, multi-channel phase noise detection of spontaneous emission sources has great application potential in physical random number generation. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system for generating high-speed physical random numbers using optical phase.

[0005] The system for generating high-speed physical random numbers using optical phase provided by this invention includes an optical emitting unit, a polarization-maintaining 2×2 optical coupler, and two phase noise detection units connected in sequence; wherein:

[0006] The optical emitting unit includes a light source ASE, a polarization-maintaining filter FF, and an erbium-doped fiber amplifier EDFA connected in sequence; the erbium-doped fiber amplifier EDFA is connected to a polarization-maintaining 2×2 optical coupler OC1;

[0007] Preferably, the light source is an amplified spontaneous emission light source, which can be composed of an erbium-doped fiber amplifier without input light, a superluminescent diode, or a semiconductor optical amplifier;

[0008] The first phase noise detection unit includes a first polarization-maintaining 3×3 optical coupler OC2, two Faraday rotator mirrors FRM1 and FRM2, and two photodetectors PD1 and PD2. One output port of the first polarization-maintaining 3×3 optical coupler OC2 is connected to the first Faraday rotator mirror FRM1 via an optical fiber. The other output port of the first polarization-maintaining 3×3 optical coupler OC2 is connected to the second Faraday rotator mirror FRM2 via an optical fiber of another length. The first polarization-maintaining 3×3 optical coupler OC2 splits the light into two arms of different lengths, the length difference of which is determined by the lengths of the two arms. The ends of the two arms are the two Faraday rotator mirrors FRM1 and FRM2. The light wave is reflected by the two Faraday rotator mirrors and then enters the first polarization-maintaining 3×3 optical coupler OC2. After coupling, it is detected by a pair of balanced photodetectors PD1 and PD2. The signals from the two detectors are subtracted to obtain the original analog signal, which is then converted into a voltage signal by a digital-to-analog converter (ADC).

[0009] The second phase noise detection unit includes a second polarization-maintaining 3×3 optical coupler OC3, two Faraday rotator mirrors FRM3 and FRM4, two photodetectors PD3 and PD4, and an adjustable delay fiber ODL. One output port of the second polarization-maintaining 3×3 optical coupler OC3 is connected to the third Faraday rotator mirror (FRM3) via an optical fiber. The other output port of the second polarization-maintaining 3×3 optical coupler OC3 is connected to the fourth Faraday rotator mirror FRM4 via an adjustable delay fiber ODL. The second polarization-maintaining 3×3 optical coupler OC3 splits the light into two arms of different lengths, the length difference of which is controlled by the adjustable delay fiber. The ends of the two arms are the two Faraday rotator mirrors FRM3 and FRM4. The light wave is reflected by the two Faraday rotator mirrors and then enters the second polarization-maintaining 3×3 optical coupler OC3. After coupling, it is detected by a pair of balanced photodetectors PD3 and PD4. The signals from the two balanced photodetectors are subtracted to obtain the original analog signal, which is then converted into a voltage signal by a digital-to-analog converter (ADC).

[0010] The first phase noise detection unit and the second phase noise detection unit need to meet the following conditions:

[0011] (1) The difference in arm length between the first phase noise detection unit and the second phase noise detection unit is greater than the coherence length of the light source;

[0012] (2) The difference in arm length between the first phase noise detection unit and the second phase noise detection unit is also greater than the coherence length of the light source.

[0013] Condition (1) ensures that the output signals of the first phase noise detection unit and the second phase noise detection unit are the phase noise of the spontaneous emission source, and condition (2) ensures that the original phase noise signal obtained by the first phase noise detection unit and the original phase noise signal obtained by the second phase noise detection unit are independent.

[0014] The optical emitting unit splits the spontaneously emitted light into two paths through a polarization-maintaining 2×2 optical coupler OC1. One path is output to the first phase noise detection unit, and the other path is transmitted to the second phase noise detection unit. The configuration of the fiber arm length in the two phase noise detection units satisfies conditions (1) and (2).

[0015] In the first phase noise detection unit, spontaneously emitted light first passes through the first polarization-maintaining 3×3 optical coupler OC2 and is input to two fiber delay arms of different lengths. After being reflected by the Faraday rotating mirror FRM, the light from the two fiber arms returns to the first polarization-maintaining 3×3 optical coupler OC2, generating beat frequency interference. The light then passes through its two output terminals and is connected to the first photodetector PD1 and the second photodetector PD2, respectively. The signals output by the two photodetectors PD1 and PD2 are subtracted to obtain the original analog sequence 1. The original analog sequence 1 is then input into the minimum entropy calculation formula. [1] H min = -log2[max(P{X=x[n])], to obtain the minimum entropy value Hmin after rounding down, and use Hmin as the value to truncate the low significant bits, so that the original simulated sequence 1 is processed into random sequence 1 through analog-to-digital conversion (ADC);

[0016] In the second phase noise detection unit, spontaneous emission light first passes through a polarization-maintaining 3×3 optical coupler (OC3) and is input to two fiber delay arms of different lengths. After being reflected by the Faraday rotating mirror (FRM), the light from the two fiber arms returns to the second polarization-maintaining 3×3 optical coupler (OC3) to generate beat frequency interference. The two outputs are then connected to the third photodetector PD3 and the fourth photodetector PD4, respectively. The signals output by the two photodetectors PD3 and PD4 are subtracted to obtain the original analog sequence 2. Similarly, Hmin is used as the value of the least significant bits to truncate the original analog sequence 2 of the second phase noise detection unit, thereby processing the original analog sequence 2 of the second phase noise detection unit into a random sequence 2 through analog-to-digital conversion (ADC). Random sequence 1 and random sequence 2 are converted into the final random sequence by alternating parallel and serial conversion.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) This invention makes full use of the phase noise of spontaneous emission light source and extracts random numbers through its phase noise. This scheme is compatible with the scheme of extracting random numbers using the intensity noise of spontaneous emission light source, thereby realizing the extraction of random numbers using both the intensity noise and phase noise of spontaneous emission light source.

[0019] (2) Compared with the phase noise of a laser source, the present invention uses the phase noise of a spontaneous emission source to extract random numbers. It does not require a long difference in the length of the interference arm and control of the source pump state. The structure is simple and easy to implement.

[0020] (3) The present invention can extend two paths to multiple paths according to the needs of random rate, so as to meet the needs of random number use at different rates. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system structure for generating high-speed physical random numbers using optical phase according to the present invention.

[0022] Figure 2 This is a flowchart illustrating the workflow of the present invention for generating high-speed physical random numbers based on optical phase noise.

[0023] Figure 3 This is the original analog sequence 1 obtained by the first phase noise detection unit of the present invention.

[0024] Figure 4 This invention provides the statistical distribution of a random sequence 1 obtained by truncating the least significant bits of the original simulated sequence 1 according to the minimum entropy.

[0025] Figure 5 This is the result of the NIST randomness test on the final random sequence in this invention.

[0026] In the diagram, the following labels are used: ASE is the light source, FF is the polarization-maintaining filter, EDFA is the erbium-doped fiber amplifier, OC1 is the polarization-maintaining 2×2 optical coupler, OC2 and OC3 are the polarization-maintaining 3×3 optical couplers, ODL is the adjustable delay fiber, FRM1, FRM2, FRM3 and FRM4 are Faraday rotator mirrors, PD1, PD2, PD3 and PD4 are photodetectors, and ADC is the digital-to-analog converter. Detailed Implementation

[0027] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0028] Example 1

[0029] like Figure 1As shown, the system for generating high-speed physical random numbers for optical phase provided by this invention includes an optical emission unit, a polarization-maintaining 2×2 optical coupler, and two phase noise detection units. The optical emission unit comprises a spontaneous emission source ASE, a polarization-maintaining filter FF, and an erbium-doped fiber amplifier EDFA connected sequentially by optical fibers. The EDFA is connected to the polarization-maintaining 2×2 optical coupler OC1. The spontaneous emission source provides a seed source for phase randomness; the polarization-maintaining filter extracts light of a specific wavelength from the spontaneous emission source; the erbium-doped fiber amplifier compensates for the optical power loss due to noise during the operation of the polarization-maintaining filter, meeting the power requirements of the first and second phase noise detection units; the polarization-maintaining 2×2 optical coupler OC1 divides the amplified spontaneous emission power into two parts, one input to the optical coupler OC2 of the first phase noise detection unit, and the other input to the optical coupler OC3 of the second phase noise detection unit.

[0030] The first phase noise detection unit includes a first polarization-maintaining 3×3 optical coupler OC2, two Faraday rotator mirrors FRM1 and FRM2, and two photodetectors PD1 and PD2. Spontaneous emission light from the optical emission unit is split into two paths by OC1. One path is connected to one input port of the first polarization-maintaining 3×3 optical coupler OC2 via an optical fiber. One output port of OC2 is connected to one Faraday rotator mirror FRM1 via an optical fiber. The other output port of OC2 is connected to another Faraday rotator mirror FRM2 via an optical fiber of a different length. The difference in fiber length between the two output ports of OC2 and FRM1 and FRM2 must exceed the coherence length of the spontaneous emission source to ensure that the phase noise of the spontaneous emission source is fully interfered through this interference structure. The other two ends of OC2 connected to OC1 are connected to a pair of balanced photodetectors PD1 and PD2, respectively. The function of PD1 and PD2 is to convert the two-position interference light signal with a 2π / 3 phase difference into an electrical signal. Subtracting PD1 from PD2 removes the DC intensity noise component common to both interference signals, retaining only the phase noise interference component.

[0031] The second phase noise detection unit includes a third polarization-maintaining 3×3 optical coupler OC3, two Faraday rotator mirrors FRM3 and FRM4, two photodetectors PD3 and PD4, and an adjustable delay fiber optic cable ODL. Spontaneous emission light from the optical emission unit is split into two paths by OC1. One path is connected to one input port of the first polarization-maintaining 3×3 optical coupler OC3 via an optical fiber, and one output port of OC3 is connected to the third Faraday rotator mirror FRM3 via an optical fiber. The other output port of OC3 is connected to the fourth Faraday rotator mirror FRM4 via ODL. The fiber length difference between the two output ports of OC3 and FRM3 and FRM4 is adjusted by ODL to ensure that the fiber length difference between the two output ports of OC3 and FRM3 and FRM4 exceeds the coherence length of the spontaneous emission source. Simultaneously, the difference between the fiber length difference between OC3 and FRM3 and FRM4 and the fiber length difference between OC2 and FRM1 and FRM2 also exceeds the coherence length of the spontaneous emission source. This is because it is necessary not only to ensure that the phase noise of the spontaneous emission source is fully interfered through the second phase noise detection unit, but also to ensure that the phase noise detected by the first and second phase noise detection units is uncorrelated. The other two ends of OC3 and OC1, which are connected to the same end, are respectively connected to a pair of balanced photodetectors PD3 and PD4. The function of PD3 and PD4 is to convert the two interfering optical signals with a phase difference of 2π / 3 into electrical signals. The subtraction of PD3 and PD4 removes the DC intensity noise component common to the two interfering signals, retaining only the phase noise interference component.

[0032] The workflow of the entire system is as follows Figure 2 As shown:

[0033] The spontaneous emission source ASE outputs phase-random spontaneous emission light with wavelength and power that meet the system's operating requirements through a polarization-maintaining filter FF and an erbium-doped fiber amplifier EDFA. The spontaneous emission light is then split into two paths by a polarization-maintaining coupler OC1.

[0034] One input is fed to a polarization-maintaining 3×3 optical coupler OC2. The two outputs of OC2 are connected to FRM1 and FRM2 respectively through optical fibers of different lengths. Spontaneous emission light is reflected at FRM1 and FRM2 through OC2 and the different length optical fibers, and returns along the original path. After converging again at OC2, it interferes to form two interference signals with a 2π / 3 phase difference. These signals are converted into electrical signals by PD1 and PD2 respectively. The DC intensity noise is extracted by subtracting the output signals of PD1 and PD2 to obtain the original analog sequence 1. The original analog sequence 1 is input into the minimum entropy calculation formula to obtain the minimum entropy value Hmin (assumed to be 5) after rounding down. Hmin is used as the value of the least significant bits. Then, the original analog sequence 1 is converted into a digital signal by an ADC (assumed to have an 8-bit resolution). That is, one analog data point can be converted into 8 bits of binary data (assumed to be 10010100). Hmin, the lower 5 bits, is taken as random sequence 1, which is 10100.

[0035] Another input is given to the polarization-maintaining 3×3 optical coupler OC3. One output of OC3 is connected to FRM3, and the other output is connected to FRM4 through the adjustable delay fiber ODL. Adjusting ODL makes the system simultaneously satisfy conditions (1) and (2). The spontaneously emitted light is reflected at FRM3 and FRM4 through OC3 and fibers of different lengths and returns along the original path. After converging again at OC3, it interferes to form two interference signals with a phase difference of 2π / 3. These signals are converted into electrical signals by PD3 and PD4 respectively. The DC intensity noise is extracted by subtracting the signals output by PD3 and PD4 to obtain the original analog sequence 2. The original analog sequence 2 is input into the minimum entropy calculation formula to obtain the minimum entropy value Hmin (generally the same as the minimum entropy of the previous path, which is 5). Hmin is used as the value for truncating the low effective bits. Then, the original analog sequence 2 is converted into a digital signal through an ADC (assuming the ADC resolution is 8 bits). That is, one analog data point can be converted into 8 bits of binary data (assuming it is 10001101). Hmin, that is, the lower 5 bits, is taken as random sequence 2, which is 01101.

[0036] Random sequence 1 (10100) and random sequence 2 (01101) are converted into the final random sequence 1001110001 by alternating parallel and serial connections.

[0037] The above embodiments can be continuously increased with the addition of phase noise detection units as needed. Each additional phase noise detection unit adds one more random sequence, thereby improving the generation rate of the final random sequence.

[0038] Taking the system in Example 1 as an example, the original analog sequence 1 obtained by the first phase noise detection unit is as follows: Figure 3As shown, the two DC inputs are removed, and the original simulation sequence 1 fluctuates randomly around 0mV. The minimum entropy of the original simulation sequence 1 is calculated to be Hmin = 5. For each simulation data point in the original simulation sequence 1, the least significant bits are truncated according to the minimum entropy of 5, and the resulting random sequence 1 is statistically distributed as follows: Figure 4 As shown, the data truncated from the lower 5 bits after analog-to-digital conversion exhibits a uniform distribution, satisfying the randomness requirement. The results of the randomness test conducted by the National Institute of Standards and Technology (NIST) on the final random sequence after alternating parallel-to-serial conversion are as follows: Figure 5 As shown, it meets all the requirements of the NIST randomness distribution.

[0039] The above embodiments are merely illustrative and do not constitute a limitation on the scope of the present invention. These embodiments can also be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the technical spirit of the present invention.

[0040] References

[0041] [1]YAMAZAKI T,UCHIDA A.Performance of Random Number Generators UsingNoise-Based Superluminescent Diode and Chaos-Based Semiconductor Lasers[J / OL].IEEE Journal of Selected Topics in Quantum Electronics,2013,19(4):0600309-0600309.DOI:10.1109 / JSTQE.2013.2246777.

Claims

1. A system for generating high-speed physical random numbers using optical phase, characterized in that, It includes a light emitting unit, a polarization-maintaining 2×2 optical coupler, and two phase noise detection units connected in sequence; wherein: The optical emitting unit includes a light source ASE, a polarization-maintaining filter FF, and an erbium-doped fiber amplifier EDFA connected in sequence; the erbium-doped fiber amplifier EDFA is connected to a polarization-maintaining 2×2 optical coupler OC1; The light source is an amplified spontaneous emission light source, which is composed of an erbium-doped fiber amplifier, a superluminescent light-emitting diode, or a semiconductor optical amplifier without input light. The first phase noise detection unit includes a first polarization-maintaining 3×3 optical coupler OC2, two Faraday rotator mirrors FRM1 and FRM2, and two photodetectors PD1 and PD2. One output port of the first polarization-maintaining 3×3 optical coupler OC2 is connected to the first Faraday rotator mirror FRM1 via an optical fiber. The other output port of the first polarization-maintaining 3×3 optical coupler OC2 is connected to the second Faraday rotator mirror FRM2 via an optical fiber of another length. The first polarization-maintaining 3×3 optical coupler OC2 splits the light into two arms of different lengths, the length difference of which is determined by the lengths of the two arms. The ends of the two arms are the two Faraday rotator mirrors FRM1 and FRM2. The light wave is reflected by the two Faraday rotator mirrors and then enters the first polarization-maintaining 3×3 optical coupler OC2. After coupling, it is detected by a pair of balanced photodetectors PD1 and PD2. The signals of the two balanced photodetectors PD1 and PD2 are subtracted to obtain the original analog signal. Then, it is converted into a voltage signal by a digital-to-analog converter (ADC). The second phase noise detection unit includes a second polarization-maintaining 3×3 optical coupler OC3, two Faraday rotator mirrors FRM3 and FRM4, two photodetectors PD3 and PD4, and an adjustable delay fiber ODL. One output port of the second polarization-maintaining 3×3 optical coupler OC3 is connected to the third Faraday rotator mirror FRM3 via an optical fiber. The other output port of the second polarization-maintaining 3×3 optical coupler OC3 is connected to the fourth Faraday rotator mirror FRM4 via an adjustable delay fiber ODL. The second polarization-maintaining 3×3 optical coupler OC3 splits the light into two arms of different lengths, the length difference of which is controlled by the adjustable delay fiber. The ends of the two arms are the two Faraday rotator mirrors FRM3 and FRM4. The light wave is reflected by the two Faraday rotator mirrors and then enters the second polarization-maintaining 3×3 optical coupler OC3. After coupling, it is detected by a pair of balanced photodetectors PD3 and PD4. The signals from the two detectors are subtracted to obtain the original analog signal, which is then converted into a voltage signal by a digital-to-analog converter (ADC).

2. The system for generating high-speed physical random numbers using optical phase according to claim 1, characterized in that, The first phase noise detection unit and the second phase noise detection unit satisfy the following conditions: (1) The difference in arm length between the first phase noise detection unit and the second phase noise detection unit is greater than the coherence length of the light source; (2) The difference in arm length between the first phase noise detection unit and the second phase noise detection unit is also greater than the coherence length of the light source; Condition (1) ensures that the output signals of the first phase noise detection unit and the second phase noise detection unit are the phase noise of the spontaneous emission source; Condition (2) ensures that the original phase noise signal obtained by the first phase noise detection unit and the original phase noise signal obtained by the second phase noise detection unit are independent. The optical emitting unit splits the spontaneous emission light into two paths through a polarization-maintaining 2×2 optical coupler OC1. One path is output to the first phase noise detection unit, and the other path is transmitted to the second phase noise detection unit. The configuration of the fiber arm length in the two phase noise detection units satisfies conditions (1) and (2); In the first phase noise detection unit, spontaneously emitted light first passes through the first polarization-maintaining 3×3 optical coupler OC2 and is input to two fiber delay arms of different lengths. After being reflected by the Faraday rotating mirror FRM, the light from the two fiber arms returns to the first polarization-maintaining 3×3 optical coupler OC2, generating beat frequency interference. The light then passes through its two output terminals and is connected to the first photodetector PD1 and the second photodetector PD2, respectively. The signals output by the two photodetectors PD1 and PD2 are subtracted to obtain the first original analog sequence. This first original analog sequence is then input into the minimum entropy calculation formula: H min =-log2[max (P{X=x[n])], obtain the minimum entropy value Hmin after rounding down, use Hmin as the value to truncate the low significant bits, and thus process the first original analog sequence into the first random sequence through analog-to-digital converter (ADC); In the second phase noise detection unit, spontaneous emission light first passes through the second polarization-maintaining 3×3 optical coupler OC3 and is input to two fiber delay arms of different lengths. After being reflected by the Faraday rotating mirror FRM, the light on the two fiber arms returns to the second polarization-maintaining 3×3 optical coupler OC3 to generate beat frequency interference. The two outputs are connected to the third photodetector PD3 and the fourth photodetector PD4 respectively. The signals output by the two photodetectors PD3 and PD4 are subtracted to obtain the second original analog sequence. Similarly, Hmin is used as the value of the least significant bit, so the second original analog sequence of the second phase noise detection unit is processed into the second random sequence by analog-to-digital converter (ADC). The first and second random sequences are converted into the final random sequence by alternating parallel and serial execution.

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