Single-photon imaging system based on polarization noise reduction

Abstract

The invention discloses a single-photon imaging system based on polarization noise reduction. The single-photon imaging system comprises a laser, a polarization beam splitter, a signal light module, a pump light module, a beam combiner, a sum frequency module and a single-photon detector. The polarization beam splitter divides laser into signal light and pump light which are perpendicular to each other, the vertical polarization signal light is converted into horizontal polarization signal light through the signal light module, the horizontal polarization signal light and the horizontal polarization pump light are combined into one path of laser, the laser is converted into sum frequency light through the sum frequency module, and the sum frequency light is detected through the single-photon detector. According to the system, through simple combined use of the polarization beam splitter, the polarization analyzer, the wavelength division multiplexer and the beam combiner, the sum frequency efficiency of nonlinear optics can be effectively improved, and the anti-noise performance of the system is improved.

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 conversely, the smaller the signal transmittance passing through the filter is, the better the noise filtering effect is. The trade-off between signal selectio...

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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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