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KR-20260065260-A - Method and Apparatus for Improving Reception Efficiency of Optical System in Quantum Cryptography Communication

KR20260065260AKR 20260065260 AKR20260065260 AKR 20260065260AKR-20260065260-A

Abstract

A method and apparatus for improving the reception efficiency of an optical system in quantum cryptographic communication are disclosed. According to one embodiment of the present disclosure, an optical system reception efficiency improvement apparatus may include a scanning unit for setting a scan area based on a first point within a Position Sensing Detector (PSD) and scanning the scan area using a Fast Steering Mirror (FSM); a feedback unit for monitoring the intensity of light detected based on points within the scan area and the frequency of quantum signals detected from the light based on points within the scan area; and a positioning unit for determining a second point within the scan area based on the intensity of the light and the frequency of the quantum signals.

Inventors

  • 이학순

Assignees

  • 에스케이텔레콤 주식회사

Dates

Publication Date
20260508
Application Date
20241101

Claims (10)

  1. A scanning unit for setting a scan area based on a first point within a PSD (Position Sensing Detector) and scanning the scan area using a FSM (Fast Steering Mirror); A feedback unit for monitoring the intensity of light detected based on points within the scan area and the frequency of quantum signals detected from the light based on points within the scan area; and An optical system reception efficiency enhancement device comprising a positioning unit for determining a second point within the scan area based on the intensity of the light and the frequency of the quantum signal.
  2. In paragraph 1, The above-mentioned first point is a pre-set point in the optical system, an optical system reception efficiency enhancement device.
  3. In paragraph 1, The above scanning unit is, An optical system reception efficiency enhancement device that scans the above-mentioned scan area in two dimensions using a raster scanning method or a spiral scanning method.
  4. In paragraph 1, The above positioning unit is, An optical system reception efficiency enhancement device that determines the point among the points within the scan area where the light intensity and the frequency of the quantum signal are maximum as the second point.
  5. In paragraph 1, The above positioning unit is, An optical system reception efficiency enhancement device that adjusts the angle of the FSM so that light is incident on the second point.
  6. A telescope for reflecting light and outputting the reflected light; A first lens for outputting parallel light by controlling the phase and direction of the reflected light; An FSM for reflecting the parallel light to control the path of the parallel light and outputting the reflected light; A wavelength filter for selectively passing light having a specific range of wavelengths among the reflected light output by the above FSM; A PSD for detecting light that has passed through the above wavelength filter; A second lens for converting light reflected by the above wavelength filter into concentrated light; A single-mode optical fiber for transmitting the above-mentioned concentrated light without loss; A detector for detecting the intensity of the concentrated light and the frequency of the quantum signal detected from the concentrated light; and An optical system comprising an optical system reception efficiency enhancement device for setting a scan area based on a first point within the PSD, scanning the scan area using the FSM, monitoring the intensity of the concentrated light and the frequency of quantum signals detected from the concentrated light based on points within the scan area, and determining a second point within the scan area where light passing through the wavelength filter is incident based on the intensity of the light and the frequency of the quantum signals.
  7. In paragraph 6, The above-mentioned first point is a pre-set point, an optical system.
  8. In paragraph 6, The above optical system reception efficiency enhancement device is, The above scan area is scanned in two dimensions using a raster scan method or a spiral scan method, and An optical system that determines the point within the scan area where the light intensity and the frequency of the quantum signal are maximum as the second point.
  9. In paragraph 6, The above optical system reception efficiency enhancement device is, An optical system that adjusts the angle of the FSM so that light is incident on the second point.
  10. A computer-readable recording medium storing instructions, wherein the instructions, when executed by the computer, cause the computer, The process of setting a scan area based on a first point within the PSD; A process of scanning points within the above scan area using an FSM; A process of monitoring the intensity of light detected based on points within the scan area and the frequency of quantum signals detected from the light based on points within the scan area; A process of determining a second point within the scan area based on the intensity of the light and the frequency of the quantum signal; and A computer-readable recording medium that performs a process of adjusting the angle of the FSM so that light is incident on the second point.

Description

Method and Apparatus for Improving Reception Efficiency of Optical System in Quantum Cryptography Communication The present invention relates to a method and apparatus for improving the reception efficiency of an optical system in quantum cryptographic communication. More specifically, the invention relates to a method and an optical system for improving the reception efficiency of an optical system by monitoring the quality of light detected in the optical system and determining the optimal position for light to be incident within a Position Sensing Detector (PSD). The following description merely provides background information related to the present embodiment and does not constitute prior art. With the recent widespread adoption of wired and wireless communication services and the rising social awareness regarding personal information, security issues concerning communication networks are emerging as a critical concern. In particular, the importance of security is increasing as it can extend beyond a personal issue to become a social one in communication networks related to the government, corporations, and the financial sector. Accordingly, quantum cryptography, which guarantees high security, is being utilized as a next-generation security technology. Quantum cryptography utilizes a Quantum Key Distribution (QKD) system to distribute quantum cryptographic keys and performs communication using these keys. Quantum cryptography is implemented through wired methods using optical fibers and wireless methods that distribute cryptographic keys through the atmosphere. In this context, wireless quantum cryptography involves encrypting quantum state information into light and transmitting it from the sender to the receiver. When wireless quantum cryptography is performed, there is a problem in which the reception efficiency of the optical system used for the communication is reduced and errors occur due to vibrations caused by factors such as wind in the atmosphere. Accordingly, research is required to correct these errors and improve the reception efficiency of the optical system. Figure 1 is a diagram illustrating an optical system in conventional wireless quantum cryptography communication. FIGS. 2a and 2b are drawings illustrating the point where light is incident within a conventional PSD (Position Sensing Detector) before correction and the point where light is incident within a PSD after correction. FIG. 3 is a diagram illustrating an optical system in wireless quantum cryptography communication according to one embodiment of the present disclosure. FIG. 4 is a block diagram illustrating an apparatus for improving the reception efficiency of an optical system in quantum cryptography communication according to one embodiment of the present disclosure. FIG. 5 is a drawing illustrating a method for determining an optimal point where light is incident within a PSD according to one embodiment of the present disclosure. FIG. 6 is a flowchart illustrating a method to improve the reception efficiency of an optical system in quantum cryptography communication according to one embodiment of the present disclosure. Some embodiments of the present disclosure are described in detail below with reference to exemplary drawings. It should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the present disclosure, if it is determined that a detailed description of related known components or functions could obscure the essence of the present disclosure, such detailed description is omitted. In describing the components of the embodiments according to the present disclosure, symbols such as first, second, i), ii), a), b), etc., may be used. These symbols are intended only to distinguish the components from other components, and the essence, order, or sequence of the components is not limited by the symbols. When a part in the specification is described as 'comprising' or 'having' a component, this means that, unless explicitly stated otherwise, it does not exclude other components but may include additional components. The detailed description set forth below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiment in which the present disclosure can be practiced. Figure 1 is a diagram illustrating an optical system in conventional wireless quantum cryptography communication. Referring to FIG. 1, in wireless quantum cryptographic communication, the optical system (10) includes a telescope (110), a first lens (120), a Fast Steering Mirror (FSM, 130), a wavelength filter (140), a Position Sensing Detector (PSD, 150), a second lens (160), a single-mode optical fiber (170), and a detector (180). The telescope (110) reflects light based on an i