The method of transferring the frequency of an optically detected magnetic resonance both up and down by an arbitrary value is implemented in a single-beam optical pumping scheme by modulating the linearly polarized beam component. The possibility of observing the Hanle resonance in a magnetic field virtually zeroed upon transition to a rotating coordinate system is demonstrated. A model experiment was carried out, confirming the fundamental feasibility and effectiveness of the method.

A new implementation of the method of optical pumping of alkaline atoms in the scheme of a highly sensitive compact single-beam sensor of a nonzero magnetic field is proposed, which allows it to be used as part of a magnetoencephalographic complex with a remote laser pumping source. The proposed method makes it possible, in particular, to pump an array of sensors with a single source of polarization-modulated resonant radiation connected to sensors by means of polarization-supporting optical fibers. A model experiment has been carried out confirming the principle feasibility and effectiveness of the method.

We present a method of laser frequency stabilization based on the linear dichroism signal in a transverse magnetic field. This method is similar to the DAVLL (Dichroic Atomic Vapor Laser Lock) method. It differs from DAVLL and from its existing modifications primarily by the fact that it uses signals of linearly polarized light caused by alignment, rather than circular refraction caused by orientation, and therefore allows us to obtain error signals at the magnetic field modulation frequency (or its second harmonic) by extremely simple means. The method allows the laser frequency to be stabilized in the vicinity of the low-frequency transition in the D1 line of Cs; it does not require strong magnetic fields or careful shielding of cells containing cesium atoms. Although the absorption line in a gas-filled cell is typically gigahertz wide, the achievable resolution, limited by the signal-to-noise ratio of photon shot noise, can reach units or tens of kilohertz in a one hertz bandwidth.

A new implementation of the method of optical pumping of alkaline atoms in the scheme of a highly sensitive compact single-beam sensor of a nonzero magnetic field is proposed, which allows it to be used as part of a magnetoencephalographic complex with a remote laser pumping source. The proposed method makes it possible, in particular, to pump an array of sensors with a single source of polarization-modulated resonant radiation connected to sensors by means of polarization-supporting optical fibers. A model experiment has been carried out confirming the principle feasibility and effectiveness of the method.

We present the results of studying the parameters of the magnetic MX resonance in an all-optical sensor built according to the two-beam Bell-Bloom scheme in nonzero ultra-weak magnetic fields in which the effects of spin-exchange broadening suppression are partially manifested. We report on the features of the resonance under these conditions. We also optimize the resonance parameters to achieve maximum sensitivity in magnetoencephalographic sensors. We demonstrate an improvement in the ultimate achievable sensitivity of an all-optical MX sensor by a factor of four or more, which in our experiment corresponds to a decrease from 13 to 3 fT/Hz1/2 in a volume of 0.13 cm3. We also report the effect of incomplete suppression of spin-exchange broadening under conditions of strong transverse modulated optical pumping, and propose a semi-empirical model to describe it.

We present the concept and the results of an investigation of an all-optical vector magnetic field sensor scheme developed for biological applications such as non-zero field magnetoencephalography and magnetocardiography. The scheme differs from the classical two-beam Bell-Bloom scheme in that the detecting laser beam is split into two beams, which are introduced into the cell in orthogonal directions, and the ratio of the amplitudes of the magnetic resonance signals in these beams and their phase difference are measured; strong optical pumping from the lower hyperfine level of the ground state ensures the resonance line narrowing, and detection in two beams is carried out in a balanced schemes by measuring the beam polarization rotation. The proposed sensor is compact, resistant to variations of parameters of laser radiation and highly sensitive to the angle of deflection of the magnetic field vector - with an estimated scalar sensitivity of the order of 16 fT/Hz1/2 in 8x8x8 mm3 cell, an angular sensitivity of 4x10-7 rad, or 0.08'', was demonstrated.

The method of transferring the frequency of an optically detected magnetic resonance both up and down by an arbitrary value is implemented in a single-beam optical pumping scheme by modulating the linearly polarized beam component. The possibility of observing the Hanle resonance in a magnetic field virtually zeroed upon transition to a rotating coordinate system is demonstrated. A model experiment was carried out, confirming the fundamental feasibility and effectiveness of the method.

We present a single-beam all-optical two-channel magnetic sensor scheme developed for biological applications such as non-zero-field magnetoencephalography and magnetocardiography. The pumping, excitation and detection of magnetic resonance in two cells are performed using a single laser beam with time-modulated linear polarization: the linear polarization of the beam switches to orthogonal every half-cycle of the Larmor frequency. Light with such characteristics can be transmitted over a single-mode polarization-maintaining fiber without any loss in the quality of the polarization characteristics. We also present an algorithm for calculating optical elements in a sensor scheme, the results of measuring the parametric dependences of magnetic resonance in cells, and the results of direct testing of a sensor in a magnetic shield. We demonstrate sensitivity at the level of 20 fT/√Hz in one sensor channel in the frequency range of 80–200 Hz.

Magnetic encephalography is currently the most informative method of functional study of the brain, since, unlike other methods, it allows one to localise deep sources of biosignals and perform three-dimensional mapping of neuronal activity. The main factors hindering the development and spread of this method are the complexity and high cost of diagnostic tools, as well as the rigidity of the requirements they impose on the spatial and temporal uniformity of the magnetic field. The prospects for desinging a device capable of largely overcoming these limitations are considered. A review of studies aimed at developing an optical sensor applicable to magnetic encephalography is presented. The all-optical single-beam nonzero-field sensor proposed by the authors earlier is separately considered.

An algorithm of approximate solution of an essentially nonlinear problem of parameters of optically detected magnetic resonance in the ground state of alkali atoms in an optically dense medium under the conditions of strong narrow-band optical pumping that induces transparency of atomic medium and partial suppression of spin-exchange broadening is proposed. Straightforward solution of the Liouville's equation is complicated in this case by the fact that relaxation time of each of the levels of the hyperfine and Zeeman structures of the ground state is determined by populations of all other levels, which results in the necessity of solving a self-consistent problem in a multilevel system and requires using supercomputers, as a rule. In the present work, approximations that allow substantially simplifying and accelerating calculation are proposed. A two-beam M-X-scheme of a magnetometric sensor is used as an example to compare the results of calculations with experimental data.

Among all inorganic perovskite, CsPbI3 has the closest ideal bang gap for solar cells. However, the instability of metal halides hinders its commercial application. The doping of A-site organic cations might improve the stability of perovskite and also make the bandgap adjustable, thus enhance its photoelectric properties. In this paper, the structure stability, electronic structure and optical properties of CsPbI3 with five different organic cations (H3NNH2+, CH3NH3+, C3H6NH2+, CH3NH2CH3+, CH3CH2NH3+) partially alternative doping instead the A site cation have been studied by using the first principles within density functional theory. In order to get accurate description of the bandstructure information, different exchange–correlation functions, e. g. PBE, PBE + SOC and HSE were used to describe the calculated systems, our calculation results indicated that the PBE exchange–correlation function can describe the electronic properties of the systems very well in this paper. Formation energy calculation indicates that all the doping systems are thermally stable; and all the doped CsPbI3 show good tolerance factor according Goldschmidt rule. Among the five different doping systems, the bandgap of doped H3NNH2+ will decrease to 1.28 eV, while the bandstructure of other doped cations will widen the bandgap. The maximum bandgap increased to 1.65 eV with doping C3H6NH2+. However, all the band structures are mainly contributed by inorganic framework. The results suggest that the structure doped organic cations can be exited stably, and the band edge of the optical absorption spectrum will be redshifted. These properties can provide research ideas for the subsequent research of A-site doping organic cations.

An experimental comparison of the methods for modulating the parameters of resonant transverse to the external magnetic field pumping radiation in a two-beam optical magnetometric sensor (so called Bell-Bloom scheme) is carried out, as well as a comparison of these methods with the standard method of radio-frequency excitation of magnetic resonance under conditions of strong laser pumping. It is shown that although the standard method allows one to achieve a greater suppression of the spin-exchange broadening of the magnetic resonance line by pumping light, the Bell-Bloom scheme has advantages that make it possible to obtain similar sensitivity values upon modulation of both the intensity and polarization of the pump light; at the same time, the Bell-Bloom scheme is potentially characterized by higher speed, which is essential for the problems of magnetoencephalography and ultra-low field magnetic resonance imaging.

The paper presents the results of measuring the cross section of the spin-exchange broadening of the magnetic resonance line in the Zeeman structure of the ground state of cesium. The analysis of the influence of measurement errors of parameters on the result was carried out, the values of the concentration of cesium vapors were refined by independent measurements.

An experimental comparison of the methods for modulating the parameters of a transverse to the external magnetic field resonant pump radiation in the two-beam scheme of an optical magnetometric sensor (the Bell–Blum scheme), as well as a comparison of these methods with the standard method of radio-frequency excitation of magnetic resonance under conditions of strong laser pumping, is carried out. It is shown that, although the standard method allows for greater suppression of the spin-exchange broadening of the magnetic resonance line by pump light, the Bell–Blum scheme is characterized by advantages that allow obtaining close sensitivities when modulating both the intensity and the polarization of the pump light; at the same time, the Bell–Blum scheme is potentially characterized by a high speed, which is essential for the problems of magnetoencephalography and magnetic resonance imaging of ultraweak fields.

Magnetic sensors developed for application in magnetoencephalography must meet a number of requirements; the main ones are compactness, sensitivity and response speed. We present a quantum optically pumped atomic sensor with cell volume of 0.5cm3 that meets these requirements and is operable in nonzero magnetic fields. The ultimate sensitivity of the sensor was estimated as (using the criteria of the ratio of the slope of the magnetic resonance signal to the shot noise spectral density) to be better than 5 fT/Hz1/2. The actual sensitivity, measured in a gradiometric scheme, reaches 13 fT/Hz1/2 per sensor. We also present a novel and fast algorithm for optimization of the geometric properties of non-zero field sensor array with respect to maximization of the information transfer rate for cortical sources.

The emission spectra of the CaO molecule behind the front of a reflected shock wave in a shock tube with a diameter of 50 mm has been studied. The spectra are recorded using a specially designed compact spectrometer with a CCD array, as well as using a spectrometer based on an upgraded MDR-12 monochromator and a Sony SLT-A77 camera as a radiation detector. The emission spectra of CaO are recorded at different gas temperatures. The obtained results can be used to test theoretical models of the emission spectra of the CaO molecule at different temperatures.

We present a method for measuring the magnetic field that allows hyperfine and Zeeman optical pumping, excitation and detection of magnetic resonance by means of a single laser beam with time-modulated ellipticity. This improvement allows us to significantly simplify the Bell-Bloom magnetometric scheme, while retaining its sensitivity. The method does not require the use of radio frequency fields, which is essential when creating arrays of sensors. The results of experimental studies demonstrate the efficiency of the proposed method and its potential applicability in most challenging magnetoencephalographic tasks.

The cross section of spin-exchange broadening of the magnetic-resonance line in the Zeeman structure of the cesium ground state has been measured. The influence of the error in measuring the parameters on the obtained result has been analyzed, and the cesium-vapor concentrations have been refined using independent measurements.

Experimental investigations of the emission spectrum of a CaO molecule behind the front of a reflected shock wave on a 50 mm diameter shock tube at the Ioffe Institute are carried out. The spectra were obtained using a compact spectrometer, as well as using a spectrometer based on an upgraded MDR-12 monochromator and a Sony SLT-A77 camera as a radiation detector. The emission spectra of CaO at different gas temperatures were obtained. The results can be used to test theoretical models of the emission spectrum of the CaO molecule at different temperatures.

In this letter, we present the results of an investigation of ultimately achievable parameters of an all-optical magnetic field sensor developed for biological applications such as nonzero field magnetoencephalography and magnetocardiography. The scheme performs hyperfine and Zeeman optical pumping, as well as excitation and detection of magnetic resonance, by means of a single laser beam with time-modulated ellipticity. It does not require the use of radio frequency fields, a feature that is essential when creating arrays of sensors. The results of experimental studies allow us to estimate the ultimate sensitivity of the scheme and optimize its optical pumping parameters.