Photon counts modulation in optical time domain reflectometry

Abstract

The quantum fluctuation of photon counting limits the field application of optical time domain reflection. A method of photon counts modulation optics time domain reflection with single photon detection at 1.55 µm is presented. The influence of quantum fluctuation can be effectively controlled by demodulation technology since quantum fluctuation shows a uniform distribution in the frequency domain. Combined with the changing of the integration time of the lock-in amplifier, the signal to noise ratio is significantly enhanced. Accordingly the signal to noise improvement ratio reaches 31.7 dB compared with the direct photon counting measurement.

Dairy intake and risk of type 2 diabetes: results of a large prospective cohort

“…[9][10][11] In China, the average intake of dairy intake was 26.47 g day −1 in 2011. 14 Our data were supported by the fact that dairy intake has significantly increased in China during recent decades. In contrast, data from the second resurvey (2013-2014) of the China Kadoorie Biobank (CKB) study indicated that the mean dairy consumption was 37.9 g day −1 .…”

“…13 In China, the average intake of dairy (mainly milk) rose from 2.06 g day −1 in 1989 to 26.47 g day −1 in 2011. 14 The latest evidence on the association between dairy intake and the risk of T2D, however, is still lacking for China. Although a recent cross-sectional study showed a positive association between dairy intake (data were collected from 2015 to 2017) and T2D in a rural population in China, 15 this study was subject to its cross-sectional design and did not differentiate between milk and yogurt.…”

Single-photon modulation spectrum

“…6(a), the exponential fitting curve (3) shows the fitting results of the modulation signal as a function of the incident photons. Similar to the magenta curve (6), it is the fitting results of the background noise in the experiment as a function of the incident photons. The error bar comes from the power variation.…”

“…The single-photon detection has been widely used, particularly in fields of quantum information, three-dimensional imaging, optical time-domain reflectometry, [1][2][3][4][5][6] etc. Photon counting has superior stability compared with analog signal measurement owing to its insensitivity to the variation of gain, and it leads to an obvious improvement in signal-to-noise ratio (SNR), which could often be exploited for the single-photon detection.…”

Quantum description and measurement for single photon modulation

“…Photon-counting modulation [7][8][9][10][11][12][13] has been used in plasma diagnostics, fluorescence detection, fluorescence lifetime measurement of single molecules, optical time domain reflectometry, spectral measurements, and so on. To obtain a precise phase signal, photon counts were reconverted to analog signals that feed into an analog lock-in amplifier.…”