Electromagnetically induced gratings (EMIGs) of atomic populations are formed in the resonant media at the interference of two or more overlapping monochromatic beams. They are of great interest in the view of the possibility of numerous applications in optics and spectroscopy. The significant progress has been achieved recently in the generation of ultrashort femto- and attosecond pulses. Such ultrashort pulses cannot provide an interference pattern because the region of their overlapping is very small and insufficient to form even few interference fringes. However, when the pulse duration is shorter than the relaxation times in the medium in the presence of a coherent interaction with the medium, they can rapidly change of the population of atomic levels owing to carrier-wave Rabi flopping. In this case, population gratings can be formed without the instantaneous overlapping of ultrashort light pulses in the medium. The latest results on the production and control of EMIGs received by means of a sequence of single- and subcycle light pulses have been reviewed. It has been shown that the unipolar subcycle pulses can be used to control more efficiently the EMIGs compared to multipolar multicycle pulses. Various applications of these gratings have been discussed in the ultrafast optics and for the holographic recording.
Electromagnetically induced gratings (EMIGs) of atomic populations are formed in the resonant media at the interference of two or more overlapping monochromatic beams. They are of great interest in the view of the possibility of numerous applications in optics and spectroscopy. The significant progress has been achieved recently in the generation of ultrashort femto- and attosecond pulses. Such ultrashort pulses cannot provide an interference pattern because the region of their overlapping is very small and insufficient to form even few interference fringes. However, when the pulse duration is shorter than the relaxation times in the medium in the presence of a coherent interaction with the medium, they can rapidly change of the population of atomic levels owing to carrier-wave Rabi flopping. In this case, population gratings can be formed without the instantaneous overlapping of ultrashort light pulses in the medium. The latest results on the production and control of EMIGs received by means of a sequence of single- and subcycle light pulses have been reviewed. It has been shown that the unipolar subcycle pulses can be used to control more efficiently the EMIGs compared to multipolar multicycle pulses. Various applications of these gratings have been discussed in the ultrafast optics and for the holographic recording.
In the case of coherent interaction with a medium of extremely short light pulses (ESPs) having a carrier frequency and harmonic shape (when the pulse durations are shorter than the population relaxation times T1 and polarization relaxation time T2 of the medium), electromagnetically induced gratings (EMIGs) of the population difference, which have a pronounced harmonic dependence on the coordinates, may appear in it. These structures can occur when pulses do not overlap or overlap in the medium. Recently, the possibility of obtaining unipolar electromagnetic pulses in the optical and adjacent ranges of non-harmonic shape, for example, rectangular and triangular, with a duration less or comparable to the duration of the extremely-short pulse in this range, has attracted interest. In this work, using the numerical solution of the system of Maxwell-Bloch equations, we study EMIG formation by rectangular attosecond pulses in a two-level resonant medium. The possibility of inducing an EMIG of a non-harmonic shape in the form of light-induced channels microresonators, (microcavities) with a size of the order of the wavelength of the resonant transition of the medium, whose parameters can be controlled, for example, by the amplitude of the incident pulses, is shown. It has been suggested that it is possible to create an EMIG of a predetermined non-harmonic shape only in the general case of using unipolar pulses. Keywords: attosecond pulses, unipolar pulses, rectangular pulses, electromagnetically induced gratings, polarization waves, light-induced microresonators.
Attosecond pulses can be used to create and control coherence in resonant media, since their duration is shorter than the population relaxation times T1 and medium polarization T2. Previously, the possibility of creating and ultrafast control of electromagnetically induced gratings (EMIG) of atomic populations in a resonant medium was shown using a sequence of extremely short light pulses, when the pulses coherently interact with the medium and do not simultaneously overlap in the medium. These studies were carried out in various approximations, when a finite number of energy levels of the medium is taken into account, or when the pulse amplitude is small. In this paper, based on a direct numerical solution of the time dependent Schredinger equation without the indicated approximations, we study the possibility of ultrafast coherent control of populations and the creation of an EMIG by a pair of attosecond pulses in a multilevel resonant medium with a low density of particles. The medium is modeled using a one-dimensional rectangular potential well with infinitely high walls. The studies performed show the possibility of ultrafast coherent control of the properties of resonant media based on quantum wells using attosecond pulses. Keywords: electromagnetically induced gratings, coherent interaction, extremely short pulses, unipolar pulses, attosecond pulses, medium coherence.
Abstract In the case of coherent interaction with a medium of extremely short light pulses (ESPs) having a carrier frequency and harmonic shape (when the pulse durations are shorter than the population relaxation times T1 and polarization relaxation time T2 of the medium), electromagnetically induced gratings (EMIGs) of the population difference, which have a pronounced harmonic dependence on the coordinates, may appear in it. These structures can occur when pulses do not overlap or overlap in the medium. Recently, the possibility of obtaining unipolar electromagnetic pulses in the optical and adjacent ranges of non-harmonic shape, for example, rectangular and triangular, with a duration less or comparable to the duration of the extremely-short pulse in this range, has attracted interest. In this work, using the numerical solution of the system of Maxwell–Bloch equations, we study EMIG formation by rectangular attosecond pulses in a two-level resonant medium. The possibility of inducing an EMIG of a non-harmonic shape in the form of light-induced channels microresonators (microcavities) with a size of the order of the wavelength of the resonant transition of the medium, whose parameters can be controlled, for example, by the amplitude of the incident pulses, is shown. It has been suggested that it is possible to create an EMIG of a predetermined non-harmonic shape only in the general case of using unipolar pulses.
Abstract Recently, the possibility of the creation, erasing and ultrafast control of polarization and population inversion gratings by sequences of few-cycle bipolar pulses interacting with a medium in a resonant and coherent way was predicted. In this case, the overlapping of pulses in the medium is not needed for the creation of gratings. In this paper, we study the possibility of the ultrafast creation and control of spatial periodic gratings in a resonant medium when subcycle unipolar pulses (that is ones containing the constant spectral component of an electric field) propagate in the coherent regime.
In the case of coherent interaction with a medium of extremely short light pulses from a carrier of a harmonic form (when the pulse durations are shorter than the population relaxation times T_1 and polarization T_2 of the medium), electromagnetically induced gratings (EMIGs) of the population difference, which have a pronounced harmonic dependence on the coordinates, may appear in it. These structures can occur when pulses do not overlap at the same time or overlap in the medium. Recently, the possibility of obtaining unipolar electromagnetic pulses of the optical and adjacent ranges of non-harmonic shape, for example, rectangular and triangular, with a duration less than or comparable to the duration of the PCR in this range, has attracted interest. In this work, using the numerical solution of the system of Maxwell-Bloch equations, we study EMIG induced by rectangular attosecond pulses in a two-level resonant medium. The possibility of inducing an EMIG of a non-harmonic form in the form of light-induced channels, a kind of microresonators, with a size of the order of the wavelength of the resonant transition of the medium, whose parameters can be controlled, for example, by the amplitude of the incident pulses, is shown. It has been suggested that it is possible to create an EMIG of a predetermined non-harmonic form only in the general case of using unipolar pulses.
In a fixed spectral range, single- and half-cycle electromagnetic pulses have the shortest duration. Half-cycle pulses are promising tools for ultrafast control of quantum systems. Previously, the possibility of using a sequence of single- and half-cycle attosecond pulses to generate and ultrafast control light-induced population difference gratings has been demonstrated. However, such studies have been carried out using different approximations. For example, when the medium is modelled in the two-level approximation. In this paper, based on the numerical solution of the system of Maxwell-Bloch equations, it is shown that it is possible to generate and control population gratings in a three-level medium without using the approximations used in previous studies. It is shown that taking into account the additional level of the medium does not lead to a violation of the effect of generating such gratings. This extends the applicability of previous results.