Polarization encoding device and quantum key distribution light source

Abstract

The invention discloses a polarization encoding device and a quantum distribution light source based on the same. The device comprises a light beam splitter, a first polarization sheet, a second polarization sheet and a phase modulator; the optical beam splitter comprises an input port, a reflection output port, a transmission output port and an output port; the first polarizing sheet and the second polarizing sheet are connected with the phase modulator through polarization maintaining optical fibers to form a bidirectional ring light path meeting the Sagnac effect; the input port receives input light through the polarization maintaining optical fiber. The device can avoid the problems of polarization mode delay, poorer stability and the like of the traditional polarization modulator dueto optical fiber path difference, and is simplified and simple to operate. The quantum distribution light source based on the device can quickly, accurately and stably realize quantum key distribution.

Description

technical field [0001] The invention relates to the field of quantum communication, in particular to a polarization encoding device and a quantum key distribution light source. Background technique [0002] At present, there are mainly two encoding methods for polarization modulation of a quantum key distribution (Quantum Key Distribution, QKD) light source. [0003] First, it is implemented using a polarization modulator. The polarization modulator is equivalent to an equi-arm interferometer, and the lengths of the two arms of the interferometer must be strictly equal to ensure the interference effect. However, due to the different refractive indices of the H and V polarization components, a polarization mode delay (PMD) phenomenon will occur after passing through the modulator. This delay is generally on the order of 10 ps for a modulator based on lithium niobate crystal. The existence of PMD will greatly limit the performance of the modulator. Generally, solutions such ...

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Problems solved by technology

Since a single-mode fiber is used for transmission between the circulator and the PBS, a polarization controller needs to be used to modulate the polarization state of the incident light, resulting in a complex system and poor integration

At the same time, this solution requires a calibration process before implementation to ensure that the 45° linearly polarized light is evenly projected onto the two arms of the PBS. The calibration process is cumbersome, and each polarization encoding device requires a calibration process before use, which is less practical. Difference

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