Trajectory-based interpretation of laser light diffraction by a sharp edge

In the diffraction pattern produced by a half-plane sharp edge when it obstructs the passage of a laser beam, two characteristic regions are noticeable. There is a central region, where it can be noticed the diffraction of laser light in the region of geometric shadow, while intensity oscillations are observed in the non-obstructed area. On both sides of the edge, there are also very long light traces along the normal to the edge of the obstacle. The theoretical explanation to this phenomenon is based on the Fresnel-Kirchhoff diffraction theory applied to the Gaussian beam propagation behind the obstacle. Here we have supplemented this explanation by considering electromagnetic flow lines, which provide a more complete interpretation of the phenomenon in terms of electric and magnetic fields and flux lines, and that can be related, at the same time, with average photon paths.Comment: 13 pages, 5 figure

Primena Husimijeve funkcije u vremensko-frekvencijskoj analizi signala

Husimi function originated in phase space formulation of quantum mechanics. This function appears naturally whenever simultaneous measurement of coordinate and impulse with maximal accuracy allowed by the Heisenberg uncertainty relation is performed on a given quantum state and it represents the probability distribution for simultaneous unsharp measurement of coordinate and impulse. Husimi function may analogously be defined for any pair of conjugated variables. In analysis of time varying signals these variables are time and frequency. In this paper we consider Husimi function in time-frequency space, we derive some properties of the function and give time-frequency analysis of some characteristic signals.U ovom radu razmotrena je Husimijeva funkcija na prostoru kanonski spregnutih promenljivih vreme-frekvencija. Izvedene su neke njene nove osobine koje su ilustrovane na nekoliko analitički zadatih signala. Pokazano je da se Husimijeva funkcija može koristiti pri vremensko-frekvencijskoj analizi signala

Primena Husimijeve funkcije u vremensko-frekvencijskoj analizi signala

Husimi function originated in phase space formulation of quantum mechanics. This function appears naturally whenever simultaneous measurement of coordinate and impulse with maximal accuracy allowed by the Heisenberg uncertainty relation is performed on a given quantum state and it represents the probability distribution for simultaneous unsharp measurement of coordinate and impulse. Husimi function may analogously be defined for any pair of conjugated variables. In analysis of time varying signals these variables are time and frequency. In this paper we consider Husimi function in time-frequency space, we derive some properties of the function and give time-frequency analysis of some characteristic signals.U ovom radu razmotrena je Husimijeva funkcija na prostoru kanonski spregnutih promenljivih vreme-frekvencija. Izvedene su neke njene nove osobine koje su ilustrovane na nekoliko analitički zadatih signala. Pokazano je da se Husimijeva funkcija može koristiti pri vremensko-frekvencijskoj analizi signala

Properties of the quantum state arising after the L-photon state has passed trough a linear quantum amplifier

We consider the system of N two-level atoms, of which N0 atoms are unexcited and N1 are excited. This system of N two-level atoms, which forms a linear quantum amplifier, interacts with a single-mode electromagnetic field. The problem of amplification of the L-photon states using such an amplifier is studied. The evolution of the electromagnetic field density matrix is described by the master equation for the field under amplification. The dynamics of this process is such that it can be described as the transformation of the scale of the phase space. The exact solution of the master equation is expressed using the transformed Husimi function of the L-quantum state of the harmonic oscillator. The properties of this function are studied and using it the average photon number and its fluctuations in the amplified state are found. © 2021, Editura Academiei Romane. All rights reserved

Combining size distribution spectrums of ambient aerosols using equivalent optical properties of nanosized particles – selected examples from the Bay of Kotor

Atmospheric aerosols in urban areas typically consist of particles of different diameters, which can range in size from a few nanometers to a few micrometers and can have a strong impact on human health [1,2]. This motivates the need to measure aerosol concentration accurately, but it is often also necessary to combine results from several instruments, with fundamentally different measurement principles. In this work, methods based on the measurement of the electrical mobility of particles, for the range of diameters from 10nm to 420nm, and the measurement of the equivalent optical diameter, for the range of diameters from 300nm to 10um, were used. Combining the overlapping region in two size distribution spectra can be used to infer equivalent optical properties of the ambient aerosol, and examples of measured and combined spectra in several urban hot spots in Bay of Kotor are analyzed in some detail. These examples will illustrate several aspects of urban aerosol properties not readily available in a typical regulatory monitoring setting, such as distribution of modes in number and mass concentration, as well as optical properties of measured aerosol. As the main result, examples of combining particle size spectrums are presented. In the process of combining the particle size spectra, it is possible to modify the distribution obtained by optical measurements by searching for the optimal value of the refractive index of the particles to obtain the best possible agreement with the size distribution obtained by measuring the electrical mobility. An equivalent refractive index as well as the equivalent shape factor of the ambient aerosol is obtained using Mie scattering theory as a theoretical framework [3]. The measurement results from the mobile monitoring campaign in Bay of Kotor in 2017 were used to elucidate the main principles of size spectrum combination, as well as to showcase diversity of equivalent optical properties of urban aerosols.XVI Photonics Workshop : Book of abstracts; March 12-15, 2023; Kopaonik, Serbi

Non-entire functions of creation and annihilation operators and their relation to phase operator

On the coherent states vertical bar alpha GT any entire function of creation and annihilation operators may be defined. We show that it is not the case for non-entire functions. Use of vertical bar alpha GT LT alpha vertical bar as identity operator for a non-entire function may lead to contradictory results. On the example of the phase operator we show how these possible contradictions may be avoided. On the coherent states |alpha GT any entire function of creation and annihilation operators may be defined. We show that it is not the case for non-entire functions. Use of |alpha GT LT alpha| as identity operator for a non-entire function may lead to contradictory results. On the example of the phase operator we show how these possible contradictions may be avoided.12th Central European Workshop on Quantum Optics, Jun 06-09, 2005, Ankara, Turke

Bohmian-Based Approach to Gauss-Maxwell Beams

Usual Gaussian beams are particular scalar solutions to the paraxial Helmholtz equation, which neglect the vector nature of light. In order to overcome this inconvenience, Simon et al. (J. Opt. Soc. Am. A 1986, 3, 536–540) found a paraxial solution to Maxwell’s equation in vacuum, which includes polarization in a natural way, though still preserving the spatial Gaussianity of the beams. In this regard, it seems that these solutions, known as Gauss-Maxwell beams, are particularly appropriate and a natural tool in optical problems dealing with Gaussian beams acted or manipulated by polarizers. In this work, inspired in the Bohmian picture of quantum mechanics, a hydrodynamic-type extension of such a formulation is provided and discussed, complementing the notion of electromagnetic field with that of (electromagnetic) flow or streamline. In this regard, the method proposed has the advantage that the rays obtained from it render a bona fide description of the spatial distribution of electromagnetic energy, since they are in compliance with the local space changes undergone by the time-averaged Poynting vector. This feature confers the approach a potential interest in the analysis and description of single-photon experiments, because of the direct connection between these rays and the average flow exhibited by swarms of identical photons (regardless of the particular motion, if any, that these entities might have), at least in the case of Gaussian input beams. In order to illustrate the approach, here it is applied to two common scenarios, namely the diffraction undergone by a single Gauss-Maxwell beam and the interference produced by a coherent superposition of two of such beams