CN114244490B - Chaotic light secret communication system based on photoelectric filtering feedback enhanced key space - Google Patents

Abstract

The invention belongs to the technical field of secret communication, and discloses a chaotic light secret communication system based on photoelectric filtering feedback enhanced key space, which comprises the following steps: the super-radiation light-emitting diode, the first light-splitting element, the first optical isolator, the second optical isolator, the first adjustable attenuator, the second adjustable attenuator, the receiver and the transmitter, wherein the transmitter comprises a first semiconductor laser, a first photoelectric detector, a first adjustable band-pass filter module and a first gain adjustable amplifier, and the receiver comprises a second semiconductor laser, a second photoelectric detector, a second adjustable band-pass filter module and a second gain adjustable amplifier. The invention effectively increases the key space in chaotic secret communication, improves the safety of communication, and has better popularization and application values.

Description

Chaotic optical secure communication system based on photoelectric filter feedback enhanced key space

Technical field

The invention belongs to the technical field of secure communication, and is specifically a chaotic light secure communication system based on photoelectric filter feedback enhanced key space.

Background technique

Today, as communication users and communication data have increased significantly, communication security has attracted more and more attention. To this end, the transmitted information must be effectively encrypted to ensure that the information is transmitted safely.

Chaotic light secure communication has the advantages of hardware encryption, compatibility with current optical communication systems, and long-distance communication, so it is widely used in secure communications. The premise of chaotic light secure communication is the need to achieve chaotic synchronization between the receiver and the transmitter, which requires that the structural parameters of the receiver and transmitter completely match or be within a certain parameter mismatch range (Phys. Rev. E, Vol. 69, P.056226, 2004). For legitimate communication parties, the structural parameters and working parameters of the transceiver are usually used as keys. The larger the key space composed of key parameters, the more difficult it is for an eavesdropper to decipher the information. Therefore, chaotic secure communication requires increasing the key space of the transceiver.

At present, research plans to increase the key space include: modulating the length of the feedback cavity with pseudo-random codes to increase the key space, and using a preset pseudo-random code sequence as a private key to modulate the cavity length or phase information of the external cavity feedback laser ( IEEEPhoton. Technol. Lett., Vol. 27, P.326-329, 2015). However, its security relies on the private key rather than the physical parameters of the device, and it cannot take advantage of the unique hardware encryption advantages of chaotic secure communication. By embedding controllable optoelectronic devices in the feedback loop, the number of devices that control the chaotic state can be increased (Opt. Express, Vol. 24, P.23439-23449, 2016).

Contents of the invention

In order to solve the risk of existing chaotic secure communications being eavesdropped and cracked, the present invention provides a chaotic optical secure communication system based on photoelectric filter feedback enhanced key space to improve the key space of the system.

In order to solve the above technical problems, the technical solution adopted by the present invention is: a chaotic light secure communication system based on photoelectric filter feedback enhanced key space, including: a superradiant light-emitting diode, a first light splitting element, a first optical isolator, a third Two optical isolators, a first adjustable attenuator, a second adjustable attenuator, a receiver and a transmitter. The transmitter includes a first semiconductor laser, a photodetector, a first adjustable bandpass filter module and a third A gain-adjustable amplifier, the receiver includes a second semiconductor laser, a second photodetector, a second adjustable band-pass filter module, and a second gain-adjustable amplifier;

The broadband optical signal emitted by the super-radiant light-emitting diode is divided into two paths through the first optical splitting element. One path is injected into the first semiconductor laser through the first optical isolator and the first adjustable attenuator, and the other path is injected into the first semiconductor laser through the second optical isolation device. The second adjustable attenuator is injected into the second semiconductor laser;

The chaotic light emitted by the first semiconductor laser is divided into three paths, one path is reflected back to the first semiconductor laser, and the other path is detected by the first photodetector and converted into a first electrical signal, and the first electrical signal is passed through the first After being filtered by the adjustable bandpass filter module and amplified by the first gain adjustable amplifier, it is positively fed back to the bias current of the first semiconductor laser, and the third channel is used as a chaotic carrier to load the message and send it to the receiving end;

The chaotic light emitted by the second semiconductor laser is divided into three paths. One path is reflected back to the second semiconductor laser through the second reflector, and the other path is detected by the second photodetector and converted into a second electrical signal. The second electrical signal The signal is filtered by the second adjustable bandpass filter module, amplified by the second gain-adjustable amplifier, and then fed back to the bias current of the second semiconductor laser; the third path serves as a demodulation carrier.

The parameter settings of the first semiconductor laser and the second semiconductor laser are the same; the parameter settings of the first optical isolator and the second optical isolator are the same; the parameter settings of the first adjustable attenuator and the second adjustable attenuator are the same; the first The photodetector and the second photodetector have the same parameter settings; the first adjustable bandpass filter module and the second adjustable bandpass filter module have the same parameter settings; the first gain adjustable amplifier and the second gain adjustable amplifier have the same parameter settings .

The chaotic light secure communication system based on photoelectric filtering feedback enhanced key space also includes a second spectroscopic element, a first reflector, a fourth spectroscopic element, a third spectroscopic element, a second reflector and a fifth spectroscopic element. element;

The chaotic light emitted by the first semiconductor laser is divided into two paths after passing through the first spectroscopic element. One path is reflected by the first reflector and then returns to the laser. The other path is divided into two beams through the fourth spectroscopic element and is incident on the first photoelectric device respectively. detectors and as chaos carriers;

The chaotic light emitted by the second semiconductor laser is divided into two beams after passing through the third beam splitting element. One beam is reflected by the second reflector and then returns to the laser. The other beam is divided into two beams through the fifth beam splitting element and is incident on the third beam. Two photodetectors and serve as demodulation carriers.

The described chaotic light secure communication system based on photoelectric filtering feedback enhanced key space also includes a second spectroscopic element, a first reflector, a third spectroscopic element and a second reflector;

The chaotic light emitted by the first semiconductor laser is divided into three beams after passing through the first spectroscopic element. One beam is reflected by the first reflector and then returns to the laser. The other two beams are respectively incident on the first photodetector and serve as chaotic carriers;

The chaotic light emitted by the second semiconductor laser is divided into three beams after passing through the third light splitting element. One beam is reflected by the second reflector and then returns to the laser. The other two beams are incident on the second photodetector and serve as demodulation carriers respectively.

The described chaotic light secure communication system based on photoelectric filter feedback enhanced key space also includes an optical filter and an erbium-doped fiber amplifier; the broadband optical signal emitted by the super-radiant light-emitting diode is passed through the optical filter and the erbium-doped fiber amplifier. After the amplifier, the incident light is divided into two paths by the first light splitting element.

The chaotic light secure communication system based on photoelectric filter feedback enhanced key space also includes a third photoelectric detector, a fourth photoelectric detector and a subtractor. The third photoelectric detector is used to convert the chaotic carrier into The fourth photodetector is used to convert the demodulated carrier wave into an electrical signal. The output ends of the third photodetector and the fourth photodetector are connected to the subtractor.

The first adjustable bandpass filter module and the second adjustable bandpass filter module include a plurality of parallel-connected tunable bandpass filters.

The communication method of the chaotic light secure communication system based on photoelectric filter feedback enhanced key space includes the following steps:

S1. Adjust the parameters of the corresponding components of the transmitter and receiver to be consistent;

S2. The message m(t) is loaded onto the chaotic carrier output by the transmitter (Alice) through chaos hiding and sent to the receiving end. The receiving end obtains the message m(t) + chaotic carrier, and then, by subtracting the synchronized The legitimate receiver (Bob) decodes the chaotic carrier output by itself to obtain the message m(t).

The present invention uses a broadband noise signal as a driving source, which has the characteristics of broadband, so that the eavesdropper cannot completely observe the changes in the time domain and thus cannot reconstruct the complete driving signal, which effectively enhances the security of communication. The transceiver module of the present invention uses a combination of photoelectric feedback and external light feedback to generate chaotic light, making the generated chaotic light more complex. At the same time, it effectively suppresses the time delay characteristics of the photoelectric feedback loop. Using this time delay feature can be used as a security physical key.

By introducing a tunable bandpass filter, an amplifier with tunable gain, the center frequency and bandwidth parameters of the filter, and the gain of the tunable amplifier into the photoelectric feedback loop of the transceiver, the invention can be used as the key to chaotic secure communication, thereby increasing the number of The system's key space.

In addition, the present invention loads the signal m(t) that needs to be transmitted onto the chaotic carrier C(t) of the transmitter (Alice) in a chaotic concealment manner. At the receiving end, m(t)+C(t) is obtained, and then the synchronized chaotic carrier C(t)' generated by the receiving module is subtracted, and then the message m(t) is obtained, realizing one-way communication.

Compared with existing chaotic secure communication solutions, the key space enhanced chaotic light secure communication method of the present invention has the following beneficial effects:

1. The present invention uses broadband noise signals as the driving source, which has the characteristics of broadband, so that the eavesdropper cannot completely observe the changes in the time domain and cannot reconstruct the complete driving signal, effectively enhancing the security of communication.

2. The system has many parameters that can be used as physical keys, and the adjustable range is large. After adjustment, the chaotic light signals generated by different parameters have little correlation. The main parameters include: the center frequency of the tunable band-pass filter, the bandwidth of the tunable band-pass filter, the gain of the amplifier, the feedback strength of the external light feedback and the delay of the photoelectric feedback loop.

To sum up, the present invention is reasonably designed, effectively increases the key space in chaotic secure communication, improves the security of communication, and has good promotion and application value.

Description of the drawings

Figure 1 is a schematic structural diagram of a chaotic optical secure communication system based on photoelectric filter feedback enhanced key space provided in Embodiment 1 of the present invention;

Figure 2 is a schematic structural diagram of a chaotic optical secure communication system based on photoelectric filter feedback enhanced key space provided in Embodiment 2 of the present invention;

Figure 3 is a schematic structural diagram of a tunable bandpass filter combination module used in Embodiment 2 of the present invention;

In the figure: 1 is a superluminescent diode; 2 is an optical filter; 3 is an erbium-doped fiber amplifier; 4 is the first spectroscopic element; 5a is the first optical isolator, 5b is the second optical isolator, and 6a is the first Adjustable attenuator, 6b is the second adjustable attenuator; 7a is the first semiconductor laser, 7b is the second semiconductor laser; 8a is the second light splitting element, 8b is the third light splitting element; 9a is the first reflector, 9b is the second reflector; 10a is the fourth spectroscopic element, 10b is the fifth spectroscopic element; 11a is the first photodetector, 11b is the second photodetector; 12 is the tunable band-pass filter; 12a is the first tunable Bandpass filter module, 12b is the second adjustable bandpass filter module; 13a is the first gain-adjustable amplifier, 13b is the second gain-adjustable amplifier; 14a is the third photodetector, and 14b is the fourth photodetector.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not All embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

Embodiment 1

As shown in Figure 1, Embodiment 1 of the present invention provides a chaotic light secure communication system based on photoelectric filter feedback enhanced key space, including: a superradiant light-emitting diode 1, a first spectroscopic element 4, and a first optical isolator 5a , second optical isolator 5b, first adjustable attenuator 6a, second adjustable attenuator 6b, receiver and transmitter, the transmitter includes a first semiconductor laser 7a, a second light splitting element 8a, a first reflective Mirror 9a, fourth spectroscopic element 10a, first photodetector 11a, first adjustable bandpass filter module 12a and first gain adjustable amplifier 13a, the receiver includes a second semiconductor laser 7b, a third spectroscopic element 8b , the second reflecting mirror 9b, the fifth spectroscopic element 10b, the second photodetector 11b, the second adjustable bandpass filter module 12b, and the second gain-adjustable amplifier 13b.

The broadband optical signal emitted by the super-radiant light-emitting diode 1 is divided into two paths through the first light splitting element 4. One path is injected into the first semiconductor laser 7a through the first optical isolator 5a and the first adjustable attenuator 6a, and the other path is injected into the first semiconductor laser 7a. The second semiconductor laser 7b is injected through the second optical isolator 5b and the second adjustable attenuator 6b.

The chaotic light emitted by the first semiconductor laser 7a is divided into two paths through the second spectroscopic element 8a, one path is reflected back to the first semiconductor laser 7a through the first reflecting mirror 9a, and the other path is divided into two paths through the fourth spectroscopic element 10a, and one path is reflected back to the first semiconductor laser 7a. The first photodetector 11a detects and converts it into a first electrical signal, which is filtered by the first adjustable bandpass filter module 12a and amplified by the first gain-adjustable amplifier 13a and then fed back to the first semiconductor laser 7a On the bias current, the other channel is used as a chaotic carrier to load the signal.

The chaotic light emitted by the second semiconductor laser 7b is divided into two paths through the third spectroscopic element 8b, one path is reflected back to the second semiconductor laser 7b through the second reflecting mirror 9b, and the other path is divided into two paths through the fifth spectroscopic element 10b, and one path is reflected back to the second semiconductor laser 7b. The second photodetector 11b detects and converts it into a second electrical signal, which is filtered by the second adjustable bandpass filter module 12b and amplified by the second gain-adjustable amplifier 13b and then fed back to the second semiconductor laser 7b On the bias current, another chaotic light signal synchronized with the transmitter is used as a demodulation carrier to decode the information loaded by the transmitter.

Specifically, in this embodiment, the first semiconductor laser 7a and the second semiconductor laser 7b have the same parameter settings; the first adjustable attenuator 6a and the second adjustable attenuator 6b have the same parameter settings; the second spectroscopic element 8a The parameter settings of the third spectroscopic element 8b are the same, the fourth spectroscopic element 10a and the fifth spectroscopic element 10b have the same parameter settings, and the light splitting ratio is 50:50. The first partial reflector 9a and the second partial reflector 9b have the same parameter settings; the first photodetector 11a and the second photodetector 11b have the same parameter settings; the first adjustable bandpass filter module 12a and the second adjustable bandpass filter The parameter settings of module 12b are the same; the parameter settings of the first gain-adjustable amplifier 13a and the second gain-adjustable amplifier 13b are the same.

Specifically, in this embodiment, the first light splitting element 4, the second light splitting element 8a, the third light splitting element 8b, the fourth light splitting element 10a and the fifth light splitting element 10b are 1×2 couplers. Its split ratio is 50:50.

In this embodiment, the second spectroscopic element 8a, the first mirror 9a, and the fourth spectroscopic element 10a are used to divide the chaotic light emitted by the first semiconductor laser 7a into three beams, and return one beam to the laser and the other beam to the laser beam. Incident to the first photodetector 11a, the third beam serves as a chaotic carrier wave; the third beam splitting element 8b, the second mirror 9b and the fifth beam splitting element 10b are used to divide the chaotic light emitted by the second semiconductor laser 7b into three beams. One of the beams is returned to the laser, the other beam is incident on the second photodetector 11b, and the third beam is used as a demodulation carrier. As an alternative to the above embodiment, in this embodiment, the first reflector 9a and the second reflector 9b can be partial reflectors, which feed back part of the light emission back to the corresponding coupler and then back to the laser, while transmitting the other part. Light can be used to load signals, or to demodulate signals. At this time, the system can omit the fourth light splitting element 10a and the fifth light splitting element 10b. In addition, in this embodiment, the second light splitting element 8a and the fourth light splitting element 10a can also be 1×3 optical fiber couplers, which directly divide the light beam output by the laser into three paths. At this time, the system can also omit the fourth light splitting element. 10a and the fifth spectroscopic element 10b.

In this embodiment, the center frequency and bandwidth parameters of the first adjustable bandpass filter module 12a and the second adjustable bandpass filter module 12b are adjustable, so that under the synchronization performance that meets the communication requirements, the center frequency of the bandpass filter Frequency and band block parameters have a certain range that can be detuned. In the same way, the different gain values of the gain-tunable amplifiers 13a and 13b further expand the parameter adjustable range and further increase the key space of the system.

Specifically, the communication method in this embodiment includes the following steps:

S1. Adjust the parameters of the corresponding components of the transmitter and receiver to be consistent, so that the sending and receiving ends can achieve a high-quality synchronization state through driving synchronization, that is, almost the same chaotic carrier wave is generated;

S2. The message m(t) is loaded onto the chaotic carrier output by the transmitter (Alice) through chaotic hiding, and is transmitted to the receiving end (Bob) through the public link. At the receiving end, the third photoelectric detector 14a performs photoelectric detection. The signal obtained by conversion I1 = message m(t) + chaotic carrier. In addition, the demodulated carrier signal output by the receiving end itself is the same as the chaotic carrier signal, so the signal obtained by photoelectric conversion through the fourth photodetector 14b is: I2 =chaotic carrier, therefore, the signals of the third photodetector 14a and the fourth photodetector 14b are subtracted through the subtractor, that is, the message m(t) is obtained by decoding.

Embodiment 2

As shown in Figure 2, Embodiment 2 of the present invention provides a system for enhancing chaotic light secure communication key space based on photoelectric filter feedback. Its specific structure is basically the same as Embodiment 1. Different from the first embodiment, this embodiment also includes an optical filter 2 and an erbium-doped fiber amplifier 3; The incident light entering the first spectroscopic element 4 is divided into two paths; one path passes through the first optical isolator 5a and the first adjustable attenuator 6a and then is injected into the first semiconductor laser 7a; the other path passes through the second optical isolator 5b and the second The second semiconductor laser 7b is injected after the adjustable attenuator 6b.

Specifically, in this embodiment, the first optical isolator 5a and the second optical isolator 5b have the same parameter settings.

In addition, as shown in FIG. 3 , in this embodiment, the first adjustable bandpass filter module 12 a and the second adjustable bandpass filter module 12 b include a plurality of parallel-connected tunable bandpass filters 12 . By adjusting the center frequency and bandwidth parameters of the filter, the bandpass filter center frequency and band block parameters have a certain detunable range under the synchronization performance that meets the communication requirements. In the same way, the gain values of different gain tunable amplifiers further expand the parameter adjustable range, thereby greatly expanding the security key space of the system. In addition, multiple tunable bandpass filters 12 are connected in parallel, so that the physical key space composed of the center frequency and bandwidth of a single filter grows exponentially as the number of filters increases.

To sum up, the present invention provides a system based on photoelectric filtering feedback to enhance the secret communication key space of chaotic light. It uses broadband noise signals as the driving source. It has the characteristics of broadband, making it impossible for eavesdroppers to completely observe the time domain. The change makes it impossible to reconstruct the complete driving signal, effectively enhancing the security of communication. This system has many parameters that can be used as physical keys and has a wide adjustable range. The main parameters include: the center frequency of each filter of the adjustable band-pass filter module, the bandwidth of each filter of the adjustable band-pass filter module, the gain of the amplifier, the feedback strength of the external light feedback and the delay of the photoelectric feedback loop. The present invention adopts an adjustable bandpass filter module, so that the physical key space composed of the center frequency and bandwidth of a single filter grows exponentially as the number of filters increases. The system has high security and can effectively resist direct filtering attacks and driven chaos attacks. The invention is reasonably designed, effectively increases the key space in chaotic secure communication, improves the security of communication, and has good promotion and application value.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention. scope.

Claims (8)

1. A chaotic light secure communication system based on photoelectric filter feedback enhanced key space, characterized by including: a superradiant light-emitting diode (1), a first spectroscopic element (4), a first optical isolator (5a), A second optical isolator (5b), a first adjustable attenuator (6a), a second adjustable attenuator (6b), a receiver and a transmitter. The transmitter includes a first semiconductor laser (7a), a first Photodetector (11a), first adjustable bandpass filter module (12a) and first gain-adjustable amplifier (13a), the receiver includes a second semiconductor laser (7b), a second photodetector (11b) , the second adjustable band-pass filter module (12b), the second gain-adjustable amplifier (13b); The broadband optical signal emitted by the superradiant light-emitting diode (1) is divided into two paths through the first light splitting element (4), and one path is injected into the light source through the first optical isolator (5a) and the first adjustable attenuator (6a). The first semiconductor laser (7a), the other path is injected into the second semiconductor laser (7b) through the second optical isolator (5b) and the second adjustable attenuator (6b); The chaotic light emitted by the first semiconductor laser (7a) is divided into three paths, one path is reflected back to the first semiconductor laser (7a), and the other path is detected by the first photodetector (11a) and converted into a first electrical signal, The first electrical signal is filtered by the first adjustable bandpass filter module (12a) and amplified by the first gain-adjustable amplifier (13a) and then fed back to the bias current of the first semiconductor laser (7a). Load the message as a chaotic carrier and send it to the receiving end; The chaotic light emitted by the second semiconductor laser (7b) is divided into three paths, one path is reflected back to the second semiconductor laser (7b), and the other path is detected by the second photodetector (11b) and converted into a second electrical signal. The second electrical signal is filtered by the second adjustable bandpass filter module (12b) and amplified by the second gain-adjustable amplifier (13b) and then fed back to the bias current of the second semiconductor laser (7b); the third path as a demodulation carrier. 2. A chaotic light secure communication system based on photoelectric filter feedback enhanced key space according to claim 1, characterized in that the parameter settings of the first semiconductor laser (7a) and the second semiconductor laser (7b) The same; the parameter settings of the first optical isolator (5a) and the second optical isolator (5b) are the same; the parameter settings of the first adjustable attenuator (6a) and the second adjustable attenuator (6b) are the same; the first photoelectric detection The parameter settings of the detector (11a) and the second photodetector (11b) are the same; the parameter settings of the first adjustable bandpass filter module (12a) and the second adjustable bandpass filter module (12b) are the same; the first gain adjustable amplifier (13a) and the second gain-adjustable amplifier (13b) have the same parameter settings. 3. A chaotic light secure communication system based on photoelectric filter feedback enhanced key space according to claim 1, characterized in that it also includes a second light splitting element (8a), a first reflector (9a), a fourth Spectroscopic element (10a), third spectroscopic element (8b), second reflecting mirror (9b) and fifth spectroscopic element (10b); The chaotic light emitted by the first semiconductor laser (7a) is divided into two paths after passing through the first spectroscopic element (4). One path is reflected by the first mirror (9a) and then returned to the laser, and the other path passes through the fourth spectroscopic element (10a). ) is divided into two beams, which are incident on the first photodetector (11a) and serve as chaotic carriers; The chaotic light emitted by the second semiconductor laser (7b) is divided into two beams after passing through the third beam splitting element (8b). One beam is reflected by the second reflector (9b) and then returns to the laser, and the other beam passes through the fifth beam splitting element. (10b) is divided into two beams, which are respectively incident on the second photodetector (11b) and used as a demodulation carrier. 4. A chaotic light secure communication system based on photoelectric filter feedback enhanced key space according to claim 1, characterized in that it also includes a second light splitting element (8a), a first reflector (9a), a third Spectroscopic element (8b), second reflecting mirror (9b); The chaotic light emitted by the first semiconductor laser (7a) is divided into three beams after passing through the first spectroscopic element (4). One beam is reflected by the first reflector (9a) and then returns to the laser. The other two beams are incident on the first beam respectively. Photodetector (11a) and as chaos carrier; The chaotic light emitted by the second semiconductor laser (7b) is divided into three beams after being passed through the third spectroscopic element (8b). One beam is reflected by the second reflector (9b) and then returns to the laser. The other two beams are incident on the second beam. photodetector (11b) and serves as demodulation carrier. 5. A chaotic optical secure communication system based on photoelectric filter feedback enhanced key space according to claim 1, characterized in that it also includes an optical filter (2) and an erbium-doped fiber amplifier (3); the ultrasonic The broadband optical signal emitted by the radiation-emitting diode (1) passes through the optical filter (2) and the erbium-doped fiber amplifier (3) and then is incident on the first light splitting element (4) and is divided into two paths. 6. A chaotic light secure communication system based on photoelectric filtering feedback enhanced key space according to claim 1, characterized in that it also includes a third photodetector (14a), a fourth photodetector (14b) and Subtractor, the third photodetector (14a) is used to convert the chaotic carrier wave into an electrical signal, the fourth photodetector (14b) is used to convert the demodulated carrier wave into an electrical signal, the third photodetector The output terminals of the detector (14a) and the fourth photodetector (14b) are connected to the subtractor. 7. A chaotic optical secure communication system based on photoelectric filter feedback enhanced key space according to claim 1, characterized in that the first adjustable bandpass filter module (12a) and the second adjustable bandpass The filtering module (12b) includes a plurality of tunable bandpass filters (12) connected in parallel. 8. A chaotic optical secure communication system based on photoelectric filter feedback enhanced key space according to claim 1, characterized in that the communication method includes the following steps: S1. Adjust the parameters of the corresponding components of the transmitter and receiver to be consistent; S2. The message m(t) is loaded onto the chaotic carrier output by the transmitter (Alice) through chaos hiding and sent to the receiving end. The receiving end obtains the message m(t) + chaotic carrier, and then, by subtracting the synchronized The legitimate receiver (Bob) decodes the chaotic carrier output by itself to obtain the message m(t).