Polarization control system and method based on straight waveguide modulator and quantum key distribution system

Abstract

The invention discloses a polarization control system and method and a quantum key distribution system. According to the method in the invention, phase modulation is carried out on signal light by using a first electro-optical crystal and a second electro-optical crystal successively; the signal light is respectively used as a horizontal polarized light component and a vertical polarized light component of o-light and e-light propagation in the first electro-optical crystal and is respectively used as e-light and o-light propagation in the second electro-optical crystal; the modulation electric fields in the first electro-optical crystal and the second electro-optical crystal are parallel to the o-light or e-light polarization direction of the corresponding electro-optical crystal and arethe same in size, but the opposite directions of the straight lines where the o-light or e-light polarization direction of the corresponding electro-optical crystal is located are opposite, and therefore the polarization state of final signal light can be conveniently controlled by controlling the modulation electric fields.

Description

technical field [0001] The present invention relates to an optical polarization control technology, more specifically to a polarization control system and method based on a straight waveguide modulator, which is especially suitable for polarization encoding in quantum key distribution. Background technique [0002] As the first quantum key distribution protocol in the world, the BB84 protocol was proposed by American scientist Charles H. Bennett and Canadian scientist Gilles Brassard in 1984. Today, the BB84 protocol has become the most widely used and researched quantum key distribution protocol with the most mature technology. The core idea of ​​the BB84 protocol is the principle of quantum uncertainty. By randomly sending two groups of quantum states under non-orthogonal basis vectors, it can ensure that eavesdroppers cannot effectively eavesdrop on this quantum state within the theoretical scope of quantum mechanics. [0003] Usually, the key distribution based on the B...

AI Technical Summary

Problems solved by technology

That is to say, the realization of polarization encoding based on fiber interferometer structures with different paths requires precise control of the optical path of the two interference arms. However, in actual production, it is difficult to strictly control the length of the interferometer arms, and there are great difficulties in the process.

[0006] In addition, polarization encoding requires high-speed and precise photon polarization state control. However, the photon polarization state is easily affected by fiber vibration and deformation, resulting in reduced or unstable polarization state encoding accuracy.

Therefore, the polarization encoding scheme based on the fiber interferometer structure also has the disadvantage of being susceptible to fiber polarization disturbances.

Images