CN215934874U - Optical fiber key distribution device based on semiconductor light source phase noise - Google Patents
Optical fiber key distribution device based on semiconductor light source phase noise Download PDFInfo
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- CN215934874U CN215934874U CN202122495480.1U CN202122495480U CN215934874U CN 215934874 U CN215934874 U CN 215934874U CN 202122495480 U CN202122495480 U CN 202122495480U CN 215934874 U CN215934874 U CN 215934874U
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Abstract
The utility model relates to the technical field of optical information security, in particular to an optical fiber key distribution device based on semiconductor light source phase noise. According to the method, the intensity noise item is eliminated by using a difference value method, and the restored signal is ensured to have higher consistency while phase noise is extracted; the utility model has ingenious and novel design, extracts the phase noise of the light source after the optical signals sent by the two communication parties undergo the same path and undergo beat frequency subtraction, and finally forms the key which is only related to the light source and the key distribution path, thereby having stronger anti-interference performance and realizing the high-speed key distribution of the two communication parties.
Description
Technical Field
The utility model relates to the technical field of optical information security, in particular to an optical fiber key distribution device based on semiconductor light source phase noise.
Background
Cryptography, an important technology for securing information, is receiving increasing attention for its potential application in mitigating the increasingly serious security threats posed by the development of communication and computer devices. On the other hand, in the encryption device, key distribution for providing a shared key to a legitimate user is one of the most critical issues, and is also a hot topic in recent years.
Key distribution schemes that are currently mainstream are largely classified into two categories according to their security sources. The former security of key distribution is called computational security, and the security mainly comes from mathematical algorithm, so that an attacker cannot crack an encryption algorithm in a short time under limited computational power to obtain a key, which represents the widely used RSA algorithm and DES algorithm at present. The security of the latter key distribution scheme based on physical principles is called information theory security, and the security is mainly guaranteed by uncertainty of occurrence of physical processes or phenomena, so the latter 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. Theoretically, a key distribution scheme based entirely on the physical layer is still secure for unlimited computing power, however the presently proposed physical layer key distribution scheme is difficult to reach very high transmission rates (typically below 1 Mbit/s) over long distances. Therefore, how to achieve high-speed and anti-interference key distribution in a long distance is an important problem restricting the development of the physical layer security key distribution technology.
SUMMERY OF THE UTILITY MODEL
The utility model provides an optical fiber key distribution device based on semiconductor light source phase noise aiming at the problems in the prior art, which eliminates the intensity noise item by utilizing a difference method, extracts the phase noise and ensures that the restored signal has higher consistency; the utility model has ingenious and novel design, extracts the phase noise of the light source after the optical signals sent by the two communication parties undergo the same path and undergo beat frequency subtraction, and finally forms the key which is only related to the light source and the key distribution path, thereby having stronger anti-interference performance and realizing the high-speed key distribution of the two communication parties.
In order to solve the technical problems, the utility model adopts the following technical scheme:
the utility model provides an optical fiber key distribution device 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, wherein the first optical fiber link is connected with the second optical fiber link;
the light source sends out optical signals, and the optical signals are respectively split into a first optical fiber link and a second optical fiber link through a first beam splitting device;
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 the third beam splitting device; the third photoelectric detector and the fourth photoelectric detector are respectively connected with the third beam splitting device.
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 between the third optical fiber link and the fourth optical fiber link is greater than the interference length of a light source.
Wherein the second beam splitter and the third beam splitter are both 3 × 3 fiber couplers.
Wherein the first photodetector, the second photodetector, the third photodetector, and the fourth photodetector have a uniform bandwidth.
The utility model has the beneficial effects that:
the utility model divides the light signal sent from the semiconductor laser which works stably into two parts which are legal and reach the communication respectively after passing through the first beam splitter, and then enters the 3 x 3 coupler to finish the beat frequency after passing through the 3 x 3 coupler and reaching the other end of the communication through the two optical fiber links, and finally the signals are received by the photoelectric detectors of the two parts which are communicated respectively, and the phase noise item related to the light source can be obtained as the basis for generating the key after the signal received by the photoelectric detector and the signal received by the other local detector subtract the intensity noise item; according to the method, the intensity noise item is eliminated by using a difference value method, and the restored signal is ensured to have higher consistency while phase noise is extracted; the utility model has ingenious and novel design, so that the phase noise of the light source is extracted after the optical signals sent by two communication parties undergo the same path and are subjected to beat frequency subtraction, and the finally formed key is only related to the light source and the key distribution path.
Drawings
Fig. 1 is a schematic diagram of an optical fiber key distribution device based on phase noise of a semiconductor light source according to the present invention.
Fig. 2 is a schematic diagram showing comparison between difference signals received by two communication parties of the optical fiber key distribution device based on phase noise of the semiconductor light source according to the present embodiment under two external optical fiber lengths of 40 km.
The reference numerals in fig. 1 to 2 include:
1. a light source; 2. a first beam splitting device; 3. a first optical fiber link; 4. a second optical fiber link; 5. a second beam splitting device; 6. a third beam splitting device; 7. a first photodetector; 8. a second photodetector; 9. a third photodetector; 10. a fourth photodetector; 11. a third optical fiber link; 12. and a fourth optical fiber link.
Detailed Description
In order to facilitate understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention. The present invention is described in detail below with reference to the attached drawings.
An optical fiber key distribution device based on semiconductor light source phase noise is shown in fig. 1 and 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;
the light source 1 sends out optical signals, and the optical signals are respectively split into a first optical fiber link 3 and a second optical fiber link 4 through a first beam splitting device 2;
the first optical fiber link 3 is connected with a second beam splitting device 5; the first photodetector 7 and the second photodetector 8 are respectively connected with the second beam splitting device 5;
the second optical fiber link 4 is connected with a third beam splitting device 6; the third photodetector 9 and the fourth photodetector 10 are respectively connected to the third beam splitter 6.
Specifically, the light source 1 and the first beam splitter 2 may be located locally on any one of the two parties of communication, or may be located in a different place from the two parties of communication; the first beam splitter 2 is used for receiving the optical signal from the optical source 1 and transmitting the optical signal to the first optical fiber link 3 and the second optical fiber link 4;
the second beam splitting device 5 is used for receiving the optical signal from the first optical fiber link 3 and transmitting the optical signal to the third beam splitting device 6; and for receiving the optical signal from the third beam splitting device 6 and transmitting it to the first photodetector 7 and the second photodetector 8;
the third beam splitting device 6 is configured to receive the optical signal from the second optical fiber link 4 and transmit the optical signal to the second beam splitting device 5; and for receiving the optical signal from the second beam splitting device 5 and transmitting it 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 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 of communication, and the third beam splitter 6, the third photodetector 9, and the fourth photodetector 10 are located locally on the other party of communication.
The utility model divides the light signal sent out from the semiconductor laser which works stably into two parts which are legal and reach the communication respectively after passing through the first beam splitter 2, and then enters the 3 x 3 coupler to finish the beat frequency after passing through the 3 x 3 coupler and reaching the other end of the communication through two optical fiber links, and finally the signals are received by the photoelectric detectors of the two parts which are communicated respectively, and the phase noise item which is related to the light source 1 can be obtained as the basis for generating the key after the signal received by the photoelectric detector and the signal received by the other local detector subtract the intensity noise item; according to the method, the intensity noise item is eliminated by using a difference value method, and the restored signal is ensured to have higher consistency while phase noise is extracted; the two communication parties can directly quantize the restored phase noise as the basis of generating the key sequence to form a generated key or form a ciphertext by means of XOR with plaintext and the like.
The phase noise in a stable semiconductor laser comes from the spontaneous emission of photons, unlike statistical pseudo-randomness, which has physical true randomness due to the uncertainty principle of quantum mechanics, and the random bit generation rate is ultimately limited only by the laser line width, which means that the digital key extracted by appropriate means from the phase noise of the laser also has true randomness. However, in addition to phase noise, intrinsic intensity noise is present when the laser is operating.
The utility model has ingenious and novel design, extracts the phase noise of the light source 1 after optical signals sent by two communication parties undergo the same path and undergo beat frequency subtraction, and finally forms the key which is only related to the light source 1 and a key distribution path.
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 greater than the interference length of the light source 1. Wherein the second beam splitter 5 and the third beam splitter 6 are both 3 × 3 fiber couplers. Wherein the bandwidths of the first photodetector 7, the second photodetector 8, the third photodetector 9, and the fourth photodetector 10 are uniform.
In this embodiment, as shown in fig. 1, the light source is a wide-spectrum superluminescent light emitting diode, and in order to obtain a sufficiently large noise variance, a noise signal is filtered by an optical filter having a bandwidth of 100GHz and a center wavelength of 1542.32nm, and then is split into two single-mode 3 × 3 couplers by a single-mode 3dB coupler (a first splitting device), and then enters two external optical fiber links of 40 km, and reaches the other end 3 × 3 coupler, and then a beat frequency is completed, and then the beat frequency is received by a high-speed photodetector. The length difference of the two external optical fiber links is 160.3 meters, which is far longer than the interference length of the filtered optical wave. When the optical power arriving at the coupler from two external fiber links is equal, the optical signals received by the two local detectors can be expressed as:
where T represents the two outer segmentsTime delay, psi, between partial fibre links due to length differencesiAnd psi2Additional phase delay for a 3 x 3 coupler, where the additional phase delay may be expressed as
According to the representation of the laser composite radiation field
Here constant E0For average field amplitude, the functions δ (t) and Φ (t) are relative intensity fluctuations and relative phase fluctuations, respectively, as a series of time-dependent zero-mean generalized stationary real numbers, which are associated with relative intensity noise and relative phase noise, respectively. Omega0Corresponding to the emission frequency of the SLD source center spectrum.
The light intensity received by the two detectors is obtained by combining the formulas (1), (2) and (4)
Here, the
Representing a time-varying phase fluctuation of the light,
can be regarded as Gaussian white noise with mean square phase deviation of
Here TcIs the coherence time of the light after passing through the filter. As the relative delay T increases, the phase difference fluctuation and the phase noise amplitude also increase. When in useT＞＞TcThe phase noise approaches the asymptotic level, which is the case in the present case, and the intensity fluctuations δ (T) and δ (T + T) are negligible in comparison, i.e. are negligible
The amplitudes of the two local receivers are subtracted at this time, and the difference signal can be expressed as
It can be seen that the difference signal here contains only a phase noise term. It should be noted that, due to the existence of the additional phase delay, to ensure that the difference signals obtained by the two communicating parties have better consistency, the additional phase delay of the two corresponding detectors should be the same.
As shown in fig. 2, the waveforms of the difference signals obtained by subtracting the original signals received by the two parties are compared within 30ns, 4 photodetectors with a bandwidth of 3.5GHz are used here, and the sampling rate of the oscilloscope is 5 GSample/s. By Pearson's correlation coefficient equation
The correlation coefficient of the two paths of difference signals obtained by calculation is 0.94, which shows that the two paths of difference signals have extremely high similarity. Then, the analog signal is converted into a digital signal sequence by using a dual-threshold quantization method, and the conversion rule is
q + and q are quantized high and low thresholds, respectively, and epsilon is a scalar quantity for determining a final threshold. Under the above conditions, by adjusting the value of epsilon, the final generation rate of the key can reach 2.3Gbit/s, and the bit error rate of the key sequences of both parties is only 0.0001%.
Although the present invention has been described with reference to the above preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the utility model as defined by the appended claims.
Claims (5)
1. An optical fiber key distribution device based on semiconductor light source phase noise is characterized in that: the optical fiber link detection device comprises a light source, a first beam splitting device, a second beam splitting device, 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 sends out optical signals, and the optical signals are respectively split into a first optical fiber link and a second optical fiber link through a first beam splitting device;
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 the third beam splitting device; the third photoelectric detector and the fourth photoelectric detector are respectively connected with the third beam splitting device.
2. The optical fiber key distribution device based on the phase noise of the semiconductor light source as claimed in claim 1, wherein: 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.
3. The optical fiber key distribution device based on the phase noise of the semiconductor light source as claimed in claim 1, wherein: the optical path difference of the third optical fiber link and the fourth optical fiber link is larger than the interference length of a light source.
4. The optical fiber key distribution device based on the phase noise of the semiconductor light source as claimed in claim 1, wherein: and the second beam splitting device and the third beam splitting device are both 3 x 3 optical fiber couplers.
5. The optical fiber key distribution device based on the phase noise of the semiconductor light source as claimed in claim 1, wherein: the bandwidths of the first photodetector, the second photodetector, the third photodetector and the fourth photodetector are consistent.
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Effective date of registration: 20220425 Address after: 523000 Workshop on the 1st and 2nd floors of building 4, small and medium-sized science and technology enterprise entrepreneurship Park, North Industrial City, Songshanhu high tech Industrial Development Zone, Dongguan City, Guangdong Province Patentee after: Dongguan advanced optical fiber Application Technology Research Institute Co.,Ltd. Patentee after: GUANGDONG FU'AN TECHNOLOGY DEVELOPMENT Co.,Ltd. Address before: 523000 Workshop on the 1st and 2nd floor, building 4, small and medium sized science and technology enterprise Pioneer Park, northern industrial city, Songshanhu high tech Development Zone, Dongguan City, Guangdong Province Patentee before: Dongguan advanced optical fiber Application Technology Research Institute Co.,Ltd. |
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Effective date of registration: 20220927 Address after: 523000 Workshop on the 1st and 2nd floors of building 4, small and medium-sized science and technology enterprise entrepreneurship Park, North Industrial City, Songshanhu high tech Industrial Development Zone, Dongguan City, Guangdong Province Patentee after: Dongguan advanced optical fiber Application Technology Research Institute Co.,Ltd. Patentee after: GUANGDONG FU'AN TECHNOLOGY DEVELOPMENT Co.,Ltd. Patentee after: Sichuan Fujinan Technology Co.,Ltd. Address before: 523000 Workshop on the 1st and 2nd floors of building 4, small and medium-sized science and technology enterprise entrepreneurship Park, North Industrial City, Songshanhu high tech Industrial Development Zone, Dongguan City, Guangdong Province Patentee before: Dongguan advanced optical fiber Application Technology Research Institute Co.,Ltd. Patentee before: GUANGDONG FU'AN TECHNOLOGY DEVELOPMENT Co.,Ltd. |
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