A single-photon imaging system based on polarization noise reduction

Abstract

The invention discloses a single photon imaging system based on polarization noise reduction, comprising a laser, a polarization beam splitter, a signal light module, a pump light module, a beam combiner, a sum-frequency module, a single photon detector; and a polarization beam splitter The laser is divided into signal light and pump light that are perpendicular to each other. The vertically polarized signal light is converted into horizontally polarized signal light by the signal light module, and combined with the horizontally polarized pump light to form a laser, which is converted into a sum-frequency light by the sum-frequency module. Single-photon detectors detect sum-frequency light. The system can effectively improve the sum-frequency efficiency of nonlinear optics and improve the anti-noise performance of the system through the simple combination of polarization beam splitter and analyzer, as well as wavelength division multiplexer and beam combiner.

Description

technical field [0001] The invention belongs to the field of quantum technology, and in particular relates to a single-photon imaging system based on polarization noise reduction, which can be widely applied to high-precision three-dimensional imaging of objects in a high-noise environment. Background technique [0002] A general single-photon imaging system uses a time-frequency filter to improve the signal-to-noise ratio of the signal, thereby improving the measurement accuracy. Time-frequency filters are the best linear systems for noise removal in signal detection, but there is a fundamental trade-off between selection efficiency (i.e., the transmittance of the signal passing through the filter) and noise filtering effectiveness. The larger the signal transmittance is, the worse the noise filtering effect is, and the smaller the signal transmittance passing through the filter is, the better the noise filtering effect is. The trade-off between signal selection efficiency...

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Problems solved by technology

[0004] Moreover, the single-photon imaging system is generally based on the coaxial optical path of transmitting and receiving. Due to the use of fiber pulse lasers, the amplifier spontaneous emission (ASE) noise will be more significant, and the ASE noise will enter the single-photon detector through the reflection of the optical devices in the imaging system, seriously affecting the measurement. result

The ASE noise generated by the laser has the same spectrum as the laser it emits and exists all the time. General noise reduction methods cannot significantly attenuate the ASE noise

More importantly, the power of the two is proportional. High-power laser emission will inevitably bring a lot of ASE noise, so the signal-to-noise ratio of the signal cannot be improved by using a higher-power laser.

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