A system and method for cross-medium wireless secure communication using circularly polarized laser

Abstract

The application discloses a cross-medium wireless safe communication system and method using circularly polarized laser. The application sends circularly polarized light by a laser signal source system, and a receiving system observes the circularly polarized light signal to exclude the influence of natural light. In addition, the application also designs a system to synchronously send a stronger vortex linearly polarized laser with the same frequency around the circularly polarized signal light beam, so that the lateral scattering light of seawater molecules and suspended particles is basically covered by noise, and signal information cannot be obtained by eavesdropping, thereby realizing safe communication which can penetrate into seawater for nearly 100 meters.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical wireless communication, and in particular relates to a system and method for realizing cross-medium wireless secure communication using circularly polarized laser. Background Art

[0002] Due to seawater's strong absorption of electromagnetic waves, the ability of electromagnetic waves of commonly used communication wavelengths to penetrate seawater is extremely limited. Wireless communication across the seawater medium between underwater and above the surface has long been a global challenge. Blue-green lasers can penetrate nearly 100 meters in seawater, making their use for communicating with underwater systems or for wireless data transmission a viable option. However, laser signals are susceptible to contamination from natural light, which can cause significant noise. Therefore, using lasers for underwater cross-medium wireless communication is not only affected by seawater absorption and scattering, but also by natural light contamination. Furthermore, laser scattering in seawater can lead to eavesdropping, posing a data security risk.

[0003] A Chinese patent (publication number: CN 117650853 A) discloses an air-sea, cross-medium, bidirectional communication system and method based on photoacoustic fusion. The system includes a dual-wavelength laser and millimeter-wave radar installed on an aerial mobile platform, and a photoacoustic receiver and transmitter installed on an underwater mobile platform. The dual-wavelength laser emits two laser beams of two wavelengths toward the water surface. One laser beam penetrates the water surface to generate a downlink acoustic signal, while the other laser beam penetrates the water surface to transmit a downlink blue-green light signal. The photoacoustic receiver receives the downlink acoustic signal and the downlink blue-green light signal. The photoacoustic transmitter transmits an uplink blue-green light signal and an uplink acoustic signal toward the water surface. The uplink acoustic signal strikes the water surface to generate microripples. The millimeter-wave radar transmits a signal toward the water surface to obtain a microripple echo signal and can also receive the uplink blue-green light signal. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a system and method for realizing cross-medium wireless secure communication using circularly polarized laser.

[0005] In a first aspect, the present invention provides a cross-medium wireless secure communication system using circularly polarized laser light, comprising a signal transmitting unit, a noise generating unit, and a signal receiving unit;

[0006] The signal transmitting unit is located on one side of the medium interface and is used to transmit a circularly polarized light signal;

[0007] The signal receiving unit is located on the other side of the medium interface and is used to observe the circularly polarized light signal;

[0008] The noise generating unit is used to generate linearly polarized noise laser light, and the linearly polarized noise laser light surrounds the circularly polarized light signal, so that an onlooker cannot obtain signal information.

[0009] In some embodiments, the signal transmitting unit includes a laser signal source, and the linearly polarized light signal emitted by the laser signal source is modulated into a circularly polarized light signal.

[0010] In some embodiments, the noise generating unit includes a noise laser source, and the noise laser source emits linearly polarized noise laser.

[0011] Furthermore, it also includes a reflector with a circular hole; the circularly polarized light signal passes through the mirror hole, and the linearly polarized noise laser is reflected by the reflector to surround the circularly polarized light signal and propagate in the same direction as the circularly polarized light signal.

[0012] Furthermore, a spiral lens is provided on the optical path from the linearly polarized noise laser to the reflector, for converting the linearly polarized noise laser into a vortex linearly polarized noise laser.

[0013] In some embodiments, the signal receiving unit adopts a polarimeter for observing the Stokes parameter V of circularly polarized laser light excluding natural light.

[0014] In a second aspect, the present invention provides a method for realizing cross-medium wireless secure communication using circularly polarized laser:

[0015] The circularly polarized light signal is emitted by the signal transmitting unit;

[0016] generating a linearly polarized noise laser by a noise generating unit, wherein the linearly polarized noise laser surrounds the circularly polarized light signal;

[0017] The circularly polarized light signal is observed by a signal receiving unit.

[0018] In some embodiments, the signal transmitting unit includes a laser signal source, and the linearly polarized light signal emitted by the laser signal source is modulated into a circularly polarized light signal.

[0019] In some embodiments, the noise generating unit includes a noise laser source, and the noise laser source emits linearly polarized noise laser.

[0020] Furthermore, the signal receiving unit adopts a polarimeter for observing the Stokes parameter V of circularly polarized laser light excluding natural light.

[0021] The present invention has the following beneficial effects: It proposes a laser cross-medium communication method and system that eliminates natural light pollution and maintains confidentiality. Specifically, a laser signal source system emits circularly polarized light, while a receiving system observes the circularly polarized light signal, eliminating the influence of natural light. Furthermore, the system is designed to simultaneously emit a stronger vortex linearly polarized laser of the same frequency to surround the circularly polarized signal beam. This effectively masks the side-scattered light from seawater molecules and suspended particles, making it impossible for bystanders to obtain signal information. This enables secure communication that can penetrate nearly 100 meters into seawater. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below with reference to the accompanying drawings and examples;

[0023] Figure 1 This is the schematic diagram of the application;

[0024] Figure 2 This is a structural diagram of an embodiment of the present application. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings and preferred examples, and the purpose and effects of the present invention will become more apparent. It should be understood that the specific examples described herein are only used to explain the present invention and are not intended to limit the present invention.

[0026] This application provides a laser cross-medium communication system and method that eliminates natural light contamination and maintains confidentiality. Specifically, a laser signal source system emits circularly polarized light, while a receiving system observes the circularly polarized light signal, eliminating the influence of natural light. Furthermore, this application also designs a system that simultaneously emits a stronger vortex linearly polarized laser of the same frequency to surround the circularly polarized signal beam. This effectively masks the side-scattered light from seawater molecules and suspended particles, making it impossible for bystanders to obtain signal information. This enables secure communication that can penetrate nearly 100 meters deep into seawater.

[0027] like Figure 1 As shown, in an embodiment of the present application, the signal transmitting unit is a laser signal source 1. The linearly polarized light signal emitted by the laser signal source is modulated into a circularly polarized light signal 2 with a right-handed polarization direction. After passing through a medium interface 3, the circularly polarized laser light 4 propagating in another medium is obtained. The signal receiving unit in this embodiment uses a polarimeter 5 that can observe the four Stokes parameters (I, Q, U, V) of the target scattered light. Since natural light has no circular polarization component (V is 0), the circularly polarized light (V) observed by the polarimeter is entirely from the laser signal of the signal source, theoretically completely eliminating the influence of natural light. In addition, the circular polarization property of circularly polarized light is essentially eliminated laterally due to multiple scattering of circularly polarized light by seawater.

[0028] Regarding communication security issues, such as Figure 2As shown, the embodiment of the present application further designs a noise generating unit, which is used to generate a linearly polarized noise laser. The linearly polarized noise laser surrounds the circularly polarized light signal, making it impossible for an onlooker to obtain signal information.

[0029] Furthermore, a circularly polarized signal light is emitted by the laser signal source 1; a linearly polarized noise light is emitted by the noise laser source 6, and the circularly polarized light signal passes through a first reflector 7 with a circular hole. The linearly polarized noise laser is reflected by the second reflector 8 and then reflected by the first reflector 7 again to surround the circularly polarized light signal and propagate in the same direction as the circularly polarized light signal; further, a spiral lens 9 is provided between the first reflector 7 and the second reflector 8, and a vortex linearly polarized noise light is generated by the spiral lens 9, and then a stronger vortex linearly polarized laser 10 of the same frequency is formed on the optical path at the rear end of the first reflector 7 (does not contain a signal, only random noise) surrounding the circularly polarized light 2, so that the side scattered light of seawater molecules and suspended particles is basically masked by the noise light, and the eavesdropper 11 cannot obtain signal information.

[0030] In summary, this application is based on mature laser, polarimeter technology and vortex light generation technology, and is very suitable for equipment and market applications, and can achieve secure communication with systems at a water depth of nearly 100 meters.

[0031] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art will still be able to modify the technical solutions described in the foregoing examples or substitute equivalents for some of the technical features therein. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the invention shall be included within the scope of protection of the invention.

Claims

1. A cross-medium wireless secure communication system using circularly polarized laser, characterized in that: It includes a signal transmitting unit, a noise generating unit and a signal receiving unit; The signal transmitting unit is located on one side of the medium interface and is used to transmit a circularly polarized light signal; The signal receiving unit is located on the other side of the medium interface and is used to observe the circularly polarized light signal; The noise generating unit is used to generate a linearly polarized noise laser, which surrounds the circularly polarized light signal so that an onlooker cannot obtain signal information; It also includes a reflector with a circular hole; the circularly polarized light signal passes through the circular hole, and the linearly polarized noise laser is reflected by the reflector to surround the circularly polarized light signal and propagate in the same direction as the circularly polarized light signal; A spiral lens is further provided on the optical path from the linearly polarized noise laser to the reflector, for converting the linearly polarized noise laser into a vortex linearly polarized noise laser; The signal receiving unit adopts a polarimeter, which is used to observe the Stokes parameter V of circularly polarized laser light excluding natural light.

2. The cross-medium wireless secure communication system using circularly polarized laser according to claim 1, characterized in that: The signal transmitting unit comprises a laser signal source, and the linearly polarized light signal emitted by the laser signal source is modulated into a circularly polarized light signal.

3. The cross-medium wireless secure communication system using circularly polarized laser according to claim 1, characterized in that: The noise generating unit comprises a noise laser source, and the noise laser source emits linearly polarized noise laser.

4. A method for implementing cross-media wireless secure communication using the system of claim 1, characterized in that: The circularly polarized light signal is emitted by the signal transmitting unit; generating a linearly polarized noise laser by a noise generating unit, wherein the linearly polarized noise laser surrounds the circularly polarized light signal; The circularly polarized light signal is observed by a signal receiving unit.

5. According to the method for realizing cross-medium wireless secure communication using circularly polarized laser according to claim 4, the signal transmitting unit comprises a laser signal source, and the linearly polarized light signal emitted by the laser signal source is modulated into a circularly polarized light signal.

6. The method for realizing cross-medium wireless secure communication using circularly polarized laser according to claim 4, characterized in that: The noise generating unit comprises a noise laser source, and the noise laser source emits linearly polarized noise laser.

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