Photon time-interval statistics of laser light scattered by brownian particles

Measurements are reported and some theoretical expressions are given for half-open photon time-interval statistics of laser light scattered by particles in brownian motion. Expressions in terms of cumulants are shown not to be valid in general.     

Photon statistics of a laser with slow inversion

We have measured the photon number probability distribution of a laser in which the inversion is not slaved to the field. For the experiments, we have used a Nd(3+):YVO(4) laser which has a sufficiently slow inversion to allow measurement of the photon fluctuations at a time scale much shorter than that of the relaxation oscillations. The photon distribution function becomes highly nonstandard (i.e., non-Poissonian) in such a laser; this is consistent with available theoretical work. We point out the relevance of our results for the case of the semiconductor microlaser.     

简并双光子激光的光子统计

从原子和场模的密度算符的主方程出发,应用Haake和Lewenstein所发展的原子变量绝热消除的算符方法,导出了简并双光子激光光场Wigner函数的福克-普朗克(Fokker-Planck)方程及其稳态解.利用稳态解的高斯近似,求得了在不同泵浦强度下,光子统计的解析结果如数值结果,并与前人的结果作了比较.     

Photon statistics of a two-photon laser

The steady state quantum statistical properties of a two-photon laser are presented for the case when the cavity loss mechanism is simulated by a single-photon process.     

Photon statistics and time dependence of two photon absorption

Two photon absorption rate is given for a finite interaction time between electromagnetic radiation and an atomic absorber. The efficiency of the two photon absorption processes for chaotic as well as for coherent field is discussed.     

Variation of laser photon statistics with cavity length

It is demonstrated by photon counting measurements that the light from a He:Ne laser becomes increasingly coherent if the cavity length is increased while the resonance frequency is kept constant. The difference between theories based on plane wave modes and gaussian shaped modes is resolvable.     

Photon statistics and autocorrelation of a multi-mode laser

The intensity fluctuation properties were experimentally studied for one mode among many oscillating longitudinal modes of an argon ion laser in a region sufficiently above threshold. The individual longitudinal mode fluctuated considerably even well above the threshold, while the laser intensity summed over all the longitudinal modes was observed stable. This fluctuation was found to be much larger than expected from the previous theoretical work by Arecchi and Ricca which did not consider the combination-tone polarization. The slowing-down and the increase of the fluctuation were observed when the excitation was lowered toward to its threshold value. The correlation time of the intensity fluctuation measured ranged from 0.7 μs to 20 μs depending on the oscillation condition.     

Photon statistics of a bad-cavity laser near threshold

A simple model of a bad-cavity laser is presented based on Haken's master equation for N pumped two-level atoms in a cavity. Via adiabatic elimination of fast variables the whole photon statistics is solved analytically near threshold. It is shown that the second order coherence function g ⁽²⁾ (0) has a very different behavior near threshold for a bad-cavity laser compared to a good-cavity laser. The power spectrum illustrates nicely the different time scales involved in the dynamics. Received: 13 November 1998 / Revised: 19 May 1998 / Accepted: 6 July 1998     

Photon statistics of pulse-pumped four-wave mixing in fiber with weak signal injection

We study the photon statistics of pulse-pumped four-wave mixing in fibers with weak coherent signal injection by measuring the intensity correlation functions of individual signal and idler fields. The experimental results show that the intensity correlation function of individual signal(idler) field g_(s(i))~(2) decreases with the intensity of signal injection. After applying narrow band filter in signal(idler) band, the value of g_(s(i))~(2) decreases from 1.9 ± 0.02(1.9 ± 0.02) to 1.03 ± 0.02(1.05 ± 0.02) when the intensity of signal injection varies from 0 to 120 photons/pulse. The results indicate that the photon statistics changes from Bose–Einstein distribution to Poisson distribution. We calculate the intensity correlation functions by using the multi-mode theory of four-wave mixing in fibers. The theoretical curves well fit the experimental results.Our investigation will be useful for mitigating the crosstalk between quantum and classical channels in a dense wavelength division multiplexing network.     

Photon statistics of laser light scattered by motile spermatozoa

The intensity of laser light scattered by swimming spermatozoa is experimentally determined to obey a gaussian distribution. This is due to the fact that the fluctuations of the electric susceptabilities of the sperm system accord with gaussian statistics. The result is obtained from the light intensity correlation data and the photoelectron counting distribution with a photoelectron counting technique. It also gives us the justification of the usual process in light intensity correlation spectroscopy of swimming spermatozoa when we get the susceptibility correlation function from the experimentally obtainable intensity correlation function.     

Observation of unique photon statistics of single artificial atom laser

We demonstrate a photonic crystal nanocavity laser essentially driven by a self-assembled InAs/GaAs single quantum dot gain and its unique photon statistics. Gain tuning measurements and photon correlation measurements indicated that a single quantum dot plays a substantial role in the laser oscillation. Photon correlation measurements showed a distinct transition from anti-bunching to Poissonian via photon bunching around the threshold with the increase of the excitation power. Numerical simulations, including contributions of other light sources besides a single quantum dot, indicated that the photon bunching feature around the threshold can be enhanced by the interfusion of incoherent photons into the cavity mode.     

Four-wave mixing: Photon statistics and the impact on a co-propagating quantum signal

We reconstruct the photon statistics of a single-photon source based on the stimulated four-wave mixing (FWM) process. We find that the statistics of the source goes from thermal, at a low power regime, to Poissonian, at a high power regime. We also study the impact of the FWM process on a co-propagating coherent quantum signal in a wavelength-division multiplexed (WDM) lightwave system. The statistics of the quantum signal changes from Poissonian to thermal when a low power is used, and remains Poissonian for a higher power. A multithermal regime is also observed when a moderate power is used.     

The photon statistics of multiphoton lasers with single photon losses

We investigate the photon statistics of a single-modem-photon laser in a generalized Scully-Lamb laser model. The solution for the stationary state is obtained by recursion although detailed balance is not available form2. The threshold condition is gained from a discussion of the photon distribution in the stationary state. At threshold we find no amplitude stabilization and somewhat above it there is bistability form2 giving rise to enhanced fluctuations. Increasing the pumping the bistability more and more disappears and the photon statistics become similar to the ones of a usual laser.     

Photon statistics of the micromaser with a Kerr medium

We have established the master equation for the micromaser with a Kerr medium,we have studied the photon statics of the micromaser with a Kerr medium field and analysed the influence of the Kerr effect on the photon statistics,The influence of the Kerr effect on the photon statistics is different in two regimes,In the thermal-atom regime,the Kerr effect produces quantum noise,and decreases the mean photon number.In the ultracold-atom regime,with the increase of the nonlinear parameter of the Kerr medium,the stability of the mean photon number and the normalized variance enhances the mean photon number,and the normalized variance exhibits collapse-revival phenomena periodically,their resonance peaks become lower,and the photon statistics of more and more regions are sub-Poissonian.     

Photon statistics in resonance fluorescence from laser deflection of an atomic beam

There is a simple relationship between the photon statistics in resonance fluorescence and the statistics of the momentum transferred to an atom by a plane traveling wave. We use this relation and the theory of atomic motion in resonant radiation to derive expressions for the mean <n> and the variance <(Δn)²> of the number of photons emitted in a given time by a two-level atom in a coherent exciting field. We find, in addition to the sub-poissonian statistics [<(Δn)²> less than <n>] previously reported for the case of resonant excitation, that super-poissonian photon statistics [<(Δn)²> greater than <n>] occur in resonance fluorescence for certain off-resonance cases. It is suggested that the sub-poissonian and the super-poissonian emission statistics might be demonstrated in a simple photodeflection experiment.     

Higher-order photon statistics of single-mode laser diodes and microchip solid-state lasers

We examine higher-order photon statisitics of laser diodes (LDs) and microchip solid-state lasers (SSLs). When the lasers are operated above lasing threshold, significantly different features of fluctuations are exhibited, which are the result of the asymmetric non-Gaussian distribution characteristics that are always present in SSLs, whereas, in contrast, Gaussian fluctuation persists in LDs. It is found that the deterministic dynamic trajectory in phase space, which is controlled by the ratio between the fluorescence and the photon lifetimes, is crucial to the corresponding behavior of higher-order statistics.     

Photon statistics of random lasers with resonant feedback

We have measured the photon statistics of random lasers with resonant feedback. With an increase of the pump intensity, the photon number distribution in a single mode changes continuously from Bose-Einstein distribution at the threshold to Poisson distribution well above the threshold. The second-order correlation coefficient drops gradually from 2 to 1. By comparing the photon statistics of a random laser with resonant feedback and that of a random laser with nonresonant feedback, we illustrate very different lasing mechanisms for the two types of random lasers.     

Change of photon statistics due to multi-photon absorption

Simple approximative equations governing the temporal behaviour of both the mean photon number, $\text{n}$, and its mean square deviation, Δn², in the process of k-photon absorption (k = 1, 2, …) are derived and solved for initial photon distributions characterized by $\text{n}$ ? 1 and Δn² ? $\text{n}$^-2. It is readily shown that such an initial distribution, in the course of attenuation, tends to a distribution for which $\text{Δn}{}^2\text{= k (2 k - 1)}{}^{-1}\text{n}$. Hence, for k > 1, the distribution is narrower than a Poisson distribution which means that photon antibunching occurs. The feasibility of a Hanbury Brown and Twiss type experiment allowing to detect this effect utilizing two-photon absorption is discussed, and an estimation of the required order of magnitude of the two-photon absorption cross-section is presented.     

Observations of non-Rayleigh statistics in the approach to photon localization

We measure the distribution of intensity of microwave radiation transmitted through absorbing random waveguides of lengths L up to localization length xi . For large intensity values the distribution is given by a negative stretched exponential to the 1/2 power, in agreement with predictions by Nieuwenhuizen and van Rossum [Phys. Rev. Lett. 74, 2674 (1995)] for diffusing waves in nonabsorbing samples, as opposed to a negative exponential given by Rayleigh statistics. The intensity distribution is well described by a transform derived by Kogan and Kaveh [Phys. Rev. B 52, R3813 (1995)] of the measured distribution of total transmission.     

Estimation of photon counting statistics with imperfect detectors

The study on photon counting statistics is of fundamental importance in quantum optics. We theoretically analyzed the imperfect detection of an arbitrary quantum state. We derived photon counting formulae for six typical quantum states(i.e.,Fock, coherent, squeeze-vacuum, thermal, odd and even coherent states) with finite quantum efficiencies and dark counts based on multiple on/off detector arrays. We applied the formulae to the simulation of multiphoton number detections and obtained both the simulated and ideal photon number distributions of each state. A comparison between the results by using the fidelity and relative entropy was carried out to evaluate the detection scheme and help select detectors for different quantum states.