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CN113852467B - A fiber-optic key distribution system based on semiconductor light source phase noise - Google Patents

A fiber-optic key distribution system based on semiconductor light source phase noise Download PDF

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CN113852467B
CN113852467B CN202111203427.8A CN202111203427A CN113852467B CN 113852467 B CN113852467 B CN 113852467B CN 202111203427 A CN202111203427 A CN 202111203427A CN 113852467 B CN113852467 B CN 113852467B
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optical fiber
photodetector
fiber link
beam splitter
optical
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CN113852467A (en
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贾波
黄鹏
陈永超
肖倩
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Dongguan Advanced Optical Fiber Application Technology Research Institute Co ltd
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Dongguan Advanced Optical Fiber Application Technology Research Institute Co ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0861—Generation of secret information including derivation or calculation of cryptographic keys or passwords
    • H04L9/0875—Generation of secret information including derivation or calculation of cryptographic keys or passwords based on channel impulse response [CIR]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/25—Arrangements specific to fibre transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
    • H04L9/083—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0861—Generation of secret information including derivation or calculation of cryptographic keys or passwords

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Computer Security & Cryptography (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)

Abstract

本发明涉及光信息安全技术领域，尤其是指一种基于半导体光源相位噪声的光纤密钥分发系统，其包括光源、第一分束器件、第二分束器件、第一光电探测器、第二光电探测器、第三光电探测器、第四光电探测器、第一光纤链路、第二光纤链路、第三光纤链路和第四光纤链路。本发明通过利用差值法消去了强度噪声项，在提取相位噪声的同时保证了还原信号具有较高的一致性；本发明设计巧妙、新颖，使得从通信双方发出的光信号经历相同的路径经过拍频相减后提取出光源的相位噪声，最后形成的密钥仅与光源自身以及密钥分发路径有关，抗干扰性更强，实现通信双方高速密钥分发。

The present invention relates to the field of optical information security technology, and in particular to an optical fiber key distribution system based on semiconductor light source phase noise, which includes a light source, a first beam splitter, a second beam splitter, a first photodetector, a second photodetector, a third photodetector, a fourth photodetector, a first optical fiber link, a second optical fiber link, a third optical fiber link, and a fourth optical fiber link. The present invention eliminates the intensity noise term by using the difference method, and ensures that the restored signal has a high consistency while extracting the phase noise; the present invention is cleverly and novelly designed, so that the optical signals emitted from the communicating parties go through the same path and the phase noise of the light source is extracted after the beat frequency is subtracted, and the key finally formed is only related to the light source itself and the key distribution path, and has stronger anti-interference performance, so as to achieve high-speed key distribution between the communicating parties.

Description

Optical fiber key distribution system based on semiconductor light source phase noise
Technical Field
The invention relates to the technical field of optical information security, in particular to an optical fiber key distribution system based on semiconductor light source phase noise.
Background
Cryptography is an important technology for securing information, and has received increasing attention for its potential application in alleviating the increasingly serious security threats posed by communications and computer system developments. In an encryption system, key distribution for providing a shared key to a legitimate user is one of the most critical problems, and is a hot topic in recent years.
Currently mainstream key distribution schemes are largely divided into two categories according to their security sources. The former security of key distribution is called computation security, and mainly comes from mathematical algorithms, so that an attacker cannot crack an encryption algorithm to obtain a key in a short time under the limited computing capability, and the security represents an RSA algorithm and a DES algorithm which are widely used at present. The security of the latter key distribution scheme based on the physical principle is called information theory security, and the security is mainly ensured by uncertainty of occurrence of a physical process or phenomenon, so that the key distribution scheme is called a physical layer key distribution scheme, and quantum key distribution is the most widely known physical layer key distribution scheme. In theory, a completely physical layer based key distribution scheme is still secure for unlimited computational power, whereas currently proposed physical layer key distribution schemes have difficulty reaching very high transmission rates (typically below 1 Mbit/s) over long distances. Therefore, how to achieve high-rate, interference-resistant key distribution over long distances is an important issue that restricts the development of physical layer security key distribution techniques.
Disclosure of Invention
The invention provides a fiber key distribution system based on semiconductor light source phase noise, which eliminates intensity noise items by utilizing a difference method, ensures that restored signals have higher consistency while extracting phase noise, has ingenious and novel design, ensures that light signals emitted from two communication parties go through the same path and extract the phase noise of the light source after undergoing beat frequency subtraction, and finally forms a key which is only related to the light source and the key distribution path, has stronger anti-interference performance and realizes the high-speed key distribution of the two communication parties.
In order to solve the technical problems, the invention adopts the following technical scheme:
The invention provides an optical fiber key distribution system based on semiconductor light source phase noise, which comprises a light source, a first beam splitter, a second beam splitter, a first photoelectric detector, a second photoelectric detector, a third photoelectric detector, a fourth photoelectric detector, a first optical fiber link, a second optical fiber link, a third optical fiber link and a fourth optical fiber link;
The light source emits light signals which are respectively split into a first optical fiber link and a second optical fiber link through a first beam splitter;
the first optical fiber link is connected with the second beam splitting device; the first photoelectric detector and the second photoelectric detector are respectively connected with the second beam splitting device;
The second optical fiber link is connected with a third beam splitter, and the third photoelectric detector and the fourth photoelectric detector are respectively connected with the third beam splitter.
The first optical fiber link, the second optical fiber link, the third optical fiber link and the fourth optical fiber link are all standard single mode optical fibers.
Wherein, the optical path difference of the third optical fiber link and the fourth optical fiber link is greater than the optical source interference length.
Wherein the second beam splitting device and the third beam splitting device are both 3×3 fiber couplers.
The bandwidths of the first photoelectric detector, the second photoelectric detector, the third photoelectric detector and the fourth photoelectric detector are consistent.
The invention has the beneficial effects that:
The invention makes the light signal sent from the semiconductor laser which works stably reach the legal two parties of communication after being split by the first beam splitter, and the light signal reaches the other end of communication through two optical fiber links after passing through the 3X 3 coupler, and then enters the 3X 3 coupler to complete beat frequency, and finally is received by the photoelectric detectors of the two parties of communication, and the phase noise item related to the light source can be obtained as the basis for generating the key after the intensity noise item is subtracted by the signal received by the photoelectric detector and the signal received by the other local detector; the invention eliminates the intensity noise item by utilizing the difference method, ensures that the restored signal has higher consistency while extracting the phase noise, has ingenious and novel design, ensures that the optical signals sent out by two communication parties go through the same path and are subjected to beat frequency subtraction to extract the phase noise of the light source, and finally forms the key which is only related to the light source and the key distribution path.
Drawings
Fig. 1 is a schematic diagram of a fiber optic key distribution system based on semiconductor light source phase noise in accordance with the present invention.
Fig. 2 is a schematic diagram showing the comparison of difference signals received by two communicating parties under two external optical fiber lengths of 40 km in the optical fiber key distribution system based on semiconductor light source phase noise in the present embodiment.
The reference numerals in fig. 1 to 2 include:
1. A light source; 2, a first beam splitter, 3, a first optical fiber link, 4, a second optical fiber link, 5, a second beam splitter, 6, a third beam splitter, 7, a first photoelectric detector, 8, a second photoelectric detector, 9, a third photoelectric detector, 10, a fourth photoelectric detector, 11, a third optical fiber link, 12, a fourth optical fiber link.
Detailed Description
The invention will be further described with reference to examples and drawings, to which reference is made, but which are not intended to limit the scope of the invention. The present invention will be described in detail below with reference to the accompanying drawings.
The optical fiber key distribution system based on semiconductor light source phase noise comprises a light source 1, a first beam splitter 2, a second beam splitter 5, a first photoelectric detector 7, a second photoelectric detector 8, a third photoelectric detector 9, a fourth photoelectric detector 10, a first optical fiber link 3, a second optical fiber link 4, a third optical fiber link 11 and a fourth optical fiber link 12, as shown in fig. 1;
the light source 1 emits light signals, and the light signals are respectively split into a first optical fiber link 3 and a second optical fiber link 4 through the first beam splitter 2;
the first optical fiber link 3 is connected with a second beam splitting device 5, and the first photoelectric detector 7 and the second photoelectric detector 8 are respectively connected with the second beam splitting device 5;
the second optical fiber link 4 is connected with a third beam splitter 6, and the third photodetector 9 and the fourth photodetector 10 are respectively connected with the third beam splitter 6.
Specifically, the light source 1 and the first beam splitter 2 may be located at either one of the two communication parties or may be located at a different place from the two communication parties, and the first beam splitter 2 is configured to receive an optical signal from the light source 1 and transmit the optical signal to the first optical fiber link 3 and the second optical fiber link 4;
the second beam splitter 5 is configured to receive an optical signal from the first optical fiber link 3 and transmit the optical signal to the third beam splitter 6, and is configured to receive an optical signal from the third beam splitter 6 and transmit the optical signal to the first photodetector 7 and the second photodetector 8;
The third beam splitter 6 is configured to receive the optical signal from the second optical fiber link 4 and transmit the optical signal to the second beam splitter 5, and is configured to receive the optical signal from the second beam splitter 5 and transmit the optical signal to the third photodetector 9 and the fourth photodetector 10;
The first optical fiber link 3, the second optical fiber link 4, the third optical fiber link 11 and the fourth optical fiber link 12 are all used for transmitting optical signals;
The first photodetector 7, the second photodetector 8, the third photodetector 9 and the fourth photodetector 10 are all used for converting optical signals into electrical signals so as to obtain corresponding keys;
The second beam splitter 5, the first photodetector 7 and the second photodetector 8 are located locally on one of the two parties, and the third beam splitter 6, the third photodetector 9 and the fourth photodetector 10 are located locally on the other party.
The invention divides the light signal from the semiconductor laser which works stably through the first beam splitter 2 to reach the legal two parties of communication respectively, reaches the other end of communication through two optical fiber links through the 3X 3 coupler, enters the 3X 3 coupler to complete beat frequency, is received by the photoelectric detectors of the two parties of communication respectively, and the signal received by the photoelectric detector is subtracted by the signal received by the other local detector to obtain the phase noise item related to the light source 1 as the basis for generating the key.
The phase noise in a stable semiconductor laser results from spontaneous emission of photons, which, unlike statistical pseudo-randomness, is physically truly random due to the uncertainty principle of quantum mechanics, and the random bit rate is ultimately limited only by the laser linewidth, which represents that the digital key extracted from the phase noise of the laser by appropriate means is truly random as well. In addition to phase noise, however, the laser is also operated with intrinsic intensity noise.
The invention has ingenious and novel design, the phase noise of the light source 1 is extracted after the light signals sent from the two communication parties go through the same path and are subjected to beat frequency subtraction, the finally formed secret key is only related to the light source 1 and the secret key distribution path, and the extracted secret key can achieve higher generation rate and randomness due to the high-speed and physical random characteristic of the phase noise of the semiconductor light source 1.
In this embodiment, the first optical fiber link 3, the second optical fiber link 4, the third optical fiber link 11, and the fourth optical fiber link 12 are all standard single-mode optical fibers. Wherein, the optical path difference between the third optical fiber link 11 and the fourth optical fiber link 12 is larger than the interference length of the light source 1. Wherein, the second beam splitting device 5 and the third beam splitting device 6 are both 3×3 optical fiber couplers. Wherein bandwidths of the first photodetector 7, the second photodetector 8, the third photodetector 9 and the fourth photodetector 10 are identical.
In this embodiment, as shown in fig. 1, the light source is a broad-spectrum superluminescent diode, in order to obtain a sufficiently large noise variance, a noise signal is filtered by an optical filter with a bandwidth of 100GHz and a center wavelength of 1542.32nm, and then split into two single-mode 3×3 couplers by a single-mode 3dB coupler (first beam splitter), and then enters two sections of 40 km external optical fiber links, and after reaching the other end 3×3 coupler, the beat frequency is completed and then received by a high-speed photodetector. The length difference of the two sections of external optical fiber links is 160.3 meters, which is far longer than the interference length of the optical wave after filtering. When the optical power reaching the coupler from the two segments of external fiber optic links is equal, the optical signals received by the two local detectors can be expressed as:
Where T represents the delay between the two external fiber links due to the difference in length, ψ j and ψ 2 are the additional phase delays for the 3×3 coupler, which can be expressed as
From the representation of the laser composite radiation field
Here the constant E 0 is the average field amplitude, the functions δ (t) and Φ (t) are the relative intensity fluctuation and the relative phase fluctuation, respectively, which are a series of zero-mean generalized stationary real numbers in time correlation, both of which are related to the relative intensity noise and the relative phase noise, respectively. Omega 0 corresponds to the emission frequency of the SLD light source center spectrum.
Combining equations (1) (2) and (4) results in two detectors receiving a light intensity of
Here, theRepresenting the time-varying phase fluctuations of the light,Can be regarded as Gaussian white noise, and the mean square phase deviation isWhere T C is the coherence time of the light after it has passed through the filter. As the relative delay T increases, the phase difference ripple and the phase noise amplitude also increase. When T > > T, the phase noise approaches a progressive level, as in the present case, while the intensity fluctuations δ (T) and δ (t+T) are negligible in comparison, i.e
In this case, the amplitude of the local two receivers is subtracted, and the difference signal can be expressed as
It can be found that only the phase noise term is included in the difference signal here. It should be noted that, due to the existence of the additional phase delays, to ensure that the difference signals obtained by the two communication parties have better consistency, the additional phase delays of the two corresponding detectors should be the same.
Fig. 2 shows waveform comparison of difference signals of the two received original signals within 30ns after subtraction, wherein 4 photodetectors with 3.5GHz bandwidth are used, and the sampling rate of an oscilloscope is 5GSample/s. By pearson correlation coefficient formula
The correlation coefficient of the two paths of difference signals obtained through calculation is 0.94, which shows that the two paths of difference signals have extremely high similarity. Converting analog signals into digital signal sequences by using a double-threshold quantization method, wherein the conversion rule is as follows
Q+ and q are quantized high and low thresholds, respectively, epsilon is a scalar that determines the final threshold. Under the above conditions, the final key generation rate can reach 2.3Gbit/s by adjusting epsilon value, and the error rate of the key sequences of both sides is only 0.0001%.
While the invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that the present invention is not limited thereto, and that the invention is not limited thereto, but is intended to be limited thereto, when the technical content disclosed above is utilized to make a little change or modification into equivalent embodiments of equivalent changes, but the technical content of the invention is not deviated from, any simple modification, equivalent changes and modification of the above embodiments are all within the scope of the technical solution of the invention.

Claims (2)

1.一种基于半导体光源相位噪声的光纤密钥分发系统，其特征在于：包括光源、第一分束器件、第二分束器件、第一光电探测器、第二光电探测器、第三光电探测器、第四光电探测器、第一光纤链路、第二光纤链路、第三光纤链路和第四光纤链路；1. An optical fiber key distribution system based on semiconductor light source phase noise, characterized in that: it includes a light source, a first beam splitting device, a second beam splitting device, a first photodetector, a second photodetector, a third photodetector, a fourth photodetector, a first optical fiber link, a second optical fiber link, a third optical fiber link and a fourth optical fiber link; 所述光源发出光信号，通过第一分束器件分别分束至第一光纤链路和第二光纤链路；The light source emits an optical signal, which is split into a first optical fiber link and a second optical fiber link respectively through a first beam splitter; 所述第一光纤链路与第二分束器件连接；所述第一光电探测器和所述第二光电探测器分别与所述第二分束器件连接；The first optical fiber link is connected to the second beam splitter; the first photodetector and the second photodetector are respectively connected to the second beam splitter; 所述第二光纤链路与第三分束器件连接；所述第三光电探测器和所述第四光电探测器分别与所述第三分束器件连接；The second optical fiber link is connected to the third beam splitter; the third photodetector and the fourth photodetector are respectively connected to the third beam splitter; 所述第三光纤链路和所述第四光纤链路的光程差大于光源干涉长度；The optical path difference between the third optical fiber link and the fourth optical fiber link is greater than the light source interference length; 所述第二分束器件和所述第三分束器件均为3×3光纤耦合器；The second beam splitting device and the third beam splitting device are both 3×3 optical fiber couplers; 所述第一光电探测器、所述第二光电探测器、所述第三光电探测器和所述第四光电探测器的带宽一致；The bandwidths of the first photodetector, the second photodetector, the third photodetector and the fourth photodetector are consistent; 所述第一分束器件用于接收来自所述光源的光信号，并传输到所述第一光纤链路和第二光纤链路；所述第二分束器件用于接收来自所述第一光纤链路的光信号，并传输到所述第三分束器件；以及用于接收来自所述第三分束器件的光信号，并传输到所述第一光电探测器和第二光电探测器；所述第三分束器件用于接收来自所述第二光纤链路的光信号，并传输到所述第二分束器件；以及用于接收来自所述第二分束器件的光信号，并传输到所述第三光电探测器和第四光电探测器；所述第一光纤链路、第二光纤链路、第三光纤链路和第四光纤链路均用于传输光信号；所述第一光电探测器、第二光电探测器、第三光电探测器、第四光电探测器均用于将光信号转换为电信号，以得到对应的密钥；所述第二分束器件与第一光电探测器、第二光电探测器位于通信双方其中一方本地，所述第三分束器件与第三光电探测器9、第四光电探测器位于通信双方另一方本地；The first beam splitter is used to receive the optical signal from the light source and transmit it to the first optical fiber link and the second optical fiber link; the second beam splitter is used to receive the optical signal from the first optical fiber link and transmit it to the third beam splitter; and is used to receive the optical signal from the third beam splitter and transmit it to the first photodetector and the second photodetector; the third beam splitter is used to receive the optical signal from the second optical fiber link and transmit it to the second beam splitter; and is used to receive the optical signal from the second beam splitter and transmit it to the third photodetector and the fourth photodetector; the first optical fiber link, the second optical fiber link, the third optical fiber link and the fourth optical fiber link are all used to transmit optical signals; the first photodetector, the second photodetector, the third photodetector and the fourth photodetector are all used to convert optical signals into electrical signals to obtain corresponding keys; the second beam splitter and the first photodetector and the second photodetector are located locally on one of the two communicating parties, and the third beam splitter and the third photodetector 9 and the fourth photodetector are located locally on the other of the two communicating parties; 从稳定工作的半导体激光器发出的光信号经过第一分束器件分束后分别到达通信的合法双方，通过3×3耦合器后经过两条光纤链路到达通信的另一端后进入3×3耦合器完成拍频，最后分别被通信双方的光电探测器接收，被光电探测器接收的信号与本地的另一个探测器接收到的信号相减减去强度噪声项之后即可得到与光源本身有关的相位噪声项作为产生密钥的依据；The optical signal emitted from the semiconductor laser working stably is split by the first beam splitter and reaches the legitimate two parties of the communication respectively. After passing through the 3×3 coupler, it passes through two optical fiber links to reach the other end of the communication and then enters the 3×3 coupler to complete the beat frequency. Finally, it is received by the photoelectric detectors of the two communicating parties respectively. The signal received by the photoelectric detector is subtracted from the signal received by another local detector minus the intensity noise term to obtain the phase noise term related to the light source itself as the basis for generating the key. 所述光源为宽谱的超辐射发光二极管，为了得到足够大的噪声方差，将噪声信号经过带宽为100GHz，中心波长1542.32nm的光学滤波器滤波后通过单模3dB耦合器分束到两个单模3×3耦合器中，再进入两段40公里的外部光纤链路中，到达另一端3×3耦合器后完成拍频再被高速光电探测器接收；两段外部光纤链路的长度差为160.3米，远大于滤波后光波的干涉长度；当从两段外部光纤链路到达耦合器的光功率相等时，两个本地探测器接收的光信号可以表示为： The light source is a wide-spectrum superluminescent diode. In order to obtain a sufficiently large noise variance, the noise signal is filtered by an optical filter with a bandwidth of 100 GHz and a central wavelength of 1542.32 nm, and then split into two single-mode 3×3 couplers through a single-mode 3dB coupler, and then enters two 40-kilometer external optical fiber links. After reaching the other end of the 3×3 coupler, the beat frequency is completed and then received by the high-speed photodetector; the length difference between the two sections of the external optical fiber link is 160.3 meters, which is much larger than the interference length of the filtered light wave; when the optical power reaching the coupler from the two sections of the external optical fiber link is equal, the optical signal received by the two local detectors can be expressed as: 这里的τ代表两段外部光纤链路间由于长度差异产生的时延，ψ1和ψ2为3×3耦合器附加的相位延迟，这里的附加相位延迟可以表示为：Here τ represents the time delay caused by the length difference between the two external optical fiber links, ψ 1 and ψ 2 are the additional phase delays of the 3×3 coupler. The additional phase delay here can be expressed as: 根据激光复合辐射场的表述：According to the description of laser composite radiation field: 这里常数E0为平均场振幅，函数δ(t)与φ(t)分别为相对强度波动和相对相位波动，为时间相关的一系列零均值广义平稳实数，二者分别与相对强度噪声和相对相位噪声相关；ω0对应于SLD光源中心光谱的发射频率；Here the constant E 0 is the mean field amplitude, the functions δ(t) and φ(t) are the relative intensity fluctuation and relative phase fluctuation, respectively, which are a series of time-dependent zero-mean wide-sense stationary real numbers, which are related to the relative intensity noise and relative phase noise, respectively; ω 0 corresponds to the emission frequency of the central spectrum of the SLD source; 将式(1)、(2)与(4)结合得到两个探测器接收的光强为：Combining equations (1), (2) and (4), we can get the light intensity received by the two detectors as: 这里代表光的时变相位波动，可以视为高斯白噪声，其均方相位偏差为这里τc为光通过滤波器后的相干时间；随着相对延迟τ的增加，相位差波动和相位噪声幅度也会增加；当τ＞＞τc时，相位噪声接近渐进水平，而相对强度波动δ(t)和δ(t+τ)相比之下忽略不计，即：here represents the time-varying phase fluctuations of light, It can be regarded as Gaussian white noise, and its mean square phase deviation is Here τc is the coherence time after the light passes through the filter; as the relative delay τ increases, the phase difference fluctuation and the phase noise amplitude will also increase; when τ>> τc , the phase noise approaches the asymptotic level, while the relative intensity fluctuations δ(t) and δ(t+τ) are negligible in comparison, that is: 此时将本地两个接收器的幅值相减，差值信号可以表示为At this time, the amplitudes of the two local receivers are subtracted, and the difference signal can be expressed as 使用了4个3.5GHz带宽的光电探测器，示波器采样率为5GSample/s；通过皮尔逊相关系数公式：Four 3.5GHz bandwidth photodetectors were used, and the oscilloscope sampling rate was 5GSample/s; using the Pearson correlation coefficient formula: 计算得到的两路差值信号的相关系数为0.94，表明二者具有极高的相似度；再使用双阈值量化的方法将模拟信号转换为数字信号序列，转换规则为：The calculated correlation coefficient of the two difference signals is 0.94, indicating that the two have extremely high similarity. The analog signal is then converted into a digital signal sequence using the double threshold quantization method. The conversion rule is: q+和q-分别为量化的高低阈值，ε为决定最终阈值的标量。q+ and q- are the high and low thresholds for quantization, respectively, and ε is a scalar that determines the final threshold. 2.根据权利要求1所述的一种基于半导体光源相位噪声的光纤密钥分发系统，其特征在于：所述第一光纤链路、所述第二光纤链路、所述第三光纤链路和所述第四光纤链路均为标准单模光纤。2. A fiber optic key distribution system based on semiconductor light source phase noise according to claim 1, characterized in that the first fiber optic link, the second fiber optic link, the third fiber optic link and the fourth fiber optic link are all standard single-mode optical fibers.
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