Single photon source based on Faraday-Sagnac loop and realization method thereof

Abstract

The invention belongs to the field of quantum private communication and specifically relates to a single photon source based on a Faraday-Sagnac loop and a realization method thereof. The single photon source is characterized in that a system of the single photon source includes a laser device, a circulator, a polarization analyzer and the Faraday-Sagnac loop which includes a four-port optical-fiber beam splitter, a phase modulator and a Faraday rotating mirror. Continuous light output by the laser device enters the four-port optical-fiber beam splitter via the circulator. The four-port optical-fiber beam splitter divides the continuous light into two beams of orthogonal-linear polarized light, which are identical in amplitude and phase. The two beams of linear polarized light are transmitted in opposite directions along the Faraday-Sagnac loop and modulated by the phase modulator at different moments. The two beams of modulated linear polarized light are overlaid in the four-port optical-fiber beam splitter and then enter the polarization analyzer after being coupled by the circulator. The advantages of the single photon source based on the Faraday-Sagnac loop are that generated light pulses have a high extinction ratio and a narrow spectral width so that polarization dispersion of the light pulses which are transmitted in a long-distance optical fiber is reduced.

Description

technical field [0001] The invention belongs to the class of quantum security communication, and in particular relates to a single photon source based on a Faraday-Sagnac ring and a realization method thereof. Background technique [0002] The emergence of quantum secure communication is a revolution in the field of secure communication. Compared with the traditional key distribution method based on algorithm complexity, the security of quantum secure communication is determined by the basic principles of physics. The "principle of non-cloning of quantum states" ensures that the information transmitted in the quantum channel can only have a unique script; at the same time, the "Heisenberg Uncertainty Principle" makes any third-party attack and eavesdropping destroy the original information, The sending and receiving ends can detect the existence of eavesdroppers by checking the bit error rate to ensure the absolute security of the transmitted information. Therefore, compare...

AI Technical Summary

Problems solved by technology

At this time, part of the light emitted by the laser is spontaneous emission light. Since the spontaneous emission spectrum is very wide, the spectral width of the output laser will be increased, which will cause serious dispersion problems in long-distance quantum security communication systems. Inconsistent polarization changes, etc.

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