Applied Spectroscopy

On the Analysis of Periodic Signals in Spectroscopy by Photon Statistics

M. Á. Rebolledo, Manuel P. Cagigal, Felipe González

Published Jul 1, 1985• 6 citations

Abstract

There are many experiments in spectroscopy in which some quantity is swept as a linear function of time. For instance, the frequency is swept when a spectrum is recorded, the magnetic field is swept in a level-crossing experiment, etc. If the intensity of the resulting light beam is small the detected signal has a large nose component. One can reduce noise by repeating the experiment periodically and using a multichannel signal analyzer to process the signal and obtain the information contained in it.

DOI: 10.1366/0003702854250248

Related papers

Determination of the period of a low-intensity square-wave-modulated light beam by measuring a square-wave transform of the time-interval probability

Rafael J. López, M. Á. Rebolledo, Fernando G. Moreno

A photon-statistics technique that is based on the time-interval probability, W(θ), is studied. This technique consists of measuring the transform QR(X)=∫0∞W(θ)R(X,θ)dθ, where R(X, θ) is a square-wave function of frequency X. This function oscillates between one and zero as θ varies. The measurement of QR(X) can be carried out in a simple way. We study the error with which the period of a low-intensity square-wave-modulated light beam can be obtained by fitting a Lorentzian curve to the experimental values of QR(X). It is found that this technique is more accurate than the intensity-correlation technique when the intensity is small. The advantage increases as the intensity of the light beam decreases. This technique can be applied for those experiments in which oscillating-intensity light beams are obtained, the period providing the required information. For instance, it can be used in laser Doppler velocimetry and in quantum-beat spectroscopy.

Journal of the Optical Society of America AMar 1, 19867 citations

Theory of periodic sampling of photon-counting distributions

Eric Jakeman, Edward R. Pike

The statistical accuracy with which moments of the intensity-fluctuation distributions of optical fields can be determined, by photon-counting experiments of finite duration, is calculated.

Journal of Physics A Mathematical and GeneralNov 1, 196817 citations

Optimization of digital filtering detection with frequency modulation for portable sensitive quantum magnetometer

雄太増山, Takayuki Iwasaki, Mutsuko Hatano +3 more

Introduction Nitrogen-vacancy (NV) centers in diamond are promising solid-state quantum sensors. The sensor can potentially monitor the real-time magnetic field at room-temperature toward the brain-machine interface. One of the biggest challenges is to implement a highly sensitive sensor in a compact system. There are two major ways to achieve it. An analog signal processing method with a lock-in amplifier is fast to obtain the signal, but it increases the size of the sensor system. The digital signal processing method with the Fourier transform is simple, but it needs more computational resources. Reducing computational resources with the simple system is an important task for monitoring a real-time magnetic field. In this study, we demonstrate an alternative method of digital signal processing with less computational resources than the Fourier transform. The computational time of the method to compute the signal from n points of data is O(n), whereas the time with Fourier transform is O(n log n). Method and Result We confirm our method with a large detection volume of the ensemble NV centers. The microwave and optical systems used in our experiment are shown in Fig. 1. The diamond sample containing NV centers was placed between the microwave resonator and a compound parabolic concentrator1. We used a coplanar waveguide resonator (CWR) with a wide center electrode for strong and uniform microwave irradiation2. The power of microwave with frequency modulation is 25 dBm before the CWR. The 300 mW laser beam to the diamond was focused with a beam diameter of about 30 μm. The fluorescence from the NV centers was collected through the compound parabolic concentrator and detected using a photodiode. The detected signal of the photodiode is analyzed by digital signal processing. The method obtains the result using a digital filter that effectively becomes a sinc filter using the orthogonality of trigonometric functions by multiplication of the acquired data by a trigonometric function. Figures 2 shows continuous-wave optical detected magnetic resonance (CW-ODMR) spectrum using the digital signal processing with a different modulation frequency of the microwave. The maximum slope and the noise of the signal become smaller with increasing the modulation frequency for different reasons. The low transition rate between quantum states of the NV center reduces the maximum slope for high modulation frequency. While the noise becomes smaller for high modulation frequency. We evaluate the maximum signal slope (Fig. 3) and noise level of the spectrum (Fig. 4). We found the reduction of the noise is greater than the reduction of the maximum slope. This work was supported by MEXT Quantum Leap Flagship Program (MEXT Q-LEAP) Grant Number JPMXS0118067395.

Dec 17, 20190 citations

Time-domain analysis of photon beams

GORDON J. TROUP

The analysis of photon beams in terms of the time intervals between photon counts is discussed; in particular, the cases of beats and of sinusoidal amplitude modulation are considered.

Proceedings of the Physical SocietyFeb 1, 19665 citations

Interference between resolvable wavelengths

Lloyd M. Davis

When a frequency stabilized dye laser (linewidth ~1 MHz) is passed through a 15.25-MHz Bragg cell, a Doppler-shifted beam emerges at a small angle. Lenses are used to cross this beam with the unshifted beam to form moving interference fringes at the photocathode of a streak camera. By using a large gain of the streak camera intensifier and an intensified low-background readout of the phosphor, single photons are detectable at the photocathode. This forms a novel Young’s experiment conducted with two resolvable frequency beams passing through one known pinhole each. If the photocathode could discriminate the frequency of the detected photon, and hence which beam it came from, or if either beam were blocked, zero visibility results. The experiment gives a direct measurement of the first-order cross-coherence at single-photon detection levels of two-frequency resolvable beams. By contrast, in quantum beat experiments only the photon probability intensity vs time is measured, and the beats are then attributed to a first-order cross-coherence of the quantum pathways. The question of the frequency spectrum and cross-spectral density of each detected photon is addressed with reference to a time-dependent physical spectrum of light.1

Annual Meeting Optical Society of AmericaJan 1, 19870 citations

Atoms used to detect non-classical light

Richard Claude Thompson

It is a well known fact that photons behave like particles in many ways. One consequence of this is that any measurements of the intensity of a light beam made by counting photons (e.g. with a photomultiplier tube) in fixed time intervals will show statistical fluctuations. In most cases these fluctuations are characterised by Poissonian statistics, which means that if the mean count is n, the fluctuations are of order n½.

Physics WorldDec 1, 19900 citations