Light magnetoabsorption in systems with quantum confinement in the field of resonant laser radiation

Near-gap light magnetoabsorption is investigated in systems with quantum confinement in the presence of IR laser radiation. It is shown that if the frequency of laser radiation is equal to the cyclotron frequency, the magnetoabsorption line shape can be fully determined by the IR radiation intensity. The frequency dependence of interband absorption of a weak electromagnetic wave can be changed significantly in the case where the laser radiation frequency is equal to the quantum-confinement frequency in parabolic quantum wells and the polarization vector is parallel to the confinement axis.     

Skin as a transformer of the polarization structure of laser radiation

Transformation of the polarization structure of a laser radiation scattered by the human skin is studied. A technique based on the matrix modeling of the optical properties of the skin considered as a superposition of epidermis and dermis, is proposed. Physical mechanisms behind the transformation of the polarization state of the scattered laser radiation are analyzed in terms of the ensemble of biospeckles.     

The influence of resonance IR laser radiation on magnetoabsorption in quantum wires

The coefficient of interband absorption of a weak electromagnetic wave by quantum wires in a transverse magnetic field and an intense laser radiation field is calculated. It is shown that, if the laser radiation frequency is equal either to the size quantization frequency (dimensional infrared resonance) or to a hybrid frequency (magnetoinfrared resonance), laser illumination can determine the shape of absorption oscillations. In particular, it is shown that the second magnetoabsorption peak is split into two peaks, the half-widths of which and the distance between which depend on the intensity of resonance laser radiation. The influence of the polarization of IR radiation on the interband absorption in quantum wires is discussed. The dynamics of the frequency dependence of the optical absorption coefficient with increasing intensity of resonance laser radiation is studied.     

Relativistic Nonlinear Optical Phenomena in the Field of Subterawatt Laser Pulses

Experiments on the generation of high optical harmonics demonstrating that relativistic regimes of interaction of radiation with matter can be implemented in the field of mid-infrared laser pulses with a peak power of 0.3 TW have been reported. The observation of relativistic phenomena at such extraordinary low peak powers of the laser field becomes possible because of the formation of a high-quality space-time mode of the laser field with an exactly specified polarization state. Such a field structure ensures a high intensity of radiation in the focus of the beam and the effective acceleration of electrons by a low-frequency electromagnetic field of a high-contrast laser pulse with an exactly specified polarization at the extremely sharp vacuum-solid interface.

     

Transformation of the polarization structure of laser radiation in optical systems

A range of questions regarding the calculation of the spatial polarization structure of laser radiation in optical systems is considered. It is shown that polarization aberrations in such systems lead to a distortion of the initial polarization structure. Requirements for an optical system intended for the transmission of the polarization structure of laser radiation and methods for the compensation of polarization aberrations are discussed.     

Defects instability under IR laser treatment in p-CdZnTe crystals

With the purpose of defect transformation and obtaining material which is suitable for some optoelectronics applications, undoped р-CdZnTe crystals were treated by IR laser radiation. For crystal properties characterization their low-temperature photoluminescence spectra before and after IR treatment were investigated. It was shown that a fine photoluminescence spectra structure, stimulated by IR laser treatment, have been generated. Observed after the IR laser treatment the transformations in р-CdZnTe photoluminescence spectra are connected with activation of background impurities and intrinsic components in inclusions, existing in untreated crystals. The background impurities, which are activated by IR laser radiation, do not produce deep levels with sufficient density of states in the gap for a high degree of compensation to be realized.     

Cubic self-action effects in photonic-crystal microcavities

Third-order nonlinear-optical self-action effects in photonic-crystal microcavities have been studied. Considerable defocusing has been observed in a nonlinear microcavity layer with a thickness much smaller than the wavelength. The polarization self-action effect that is manifested as the significant rotation of the polarization plane of laser radiation resonant to the microcavity mode has been observed. It has been shown that the polarization rotation angle is a linear function of the radiation power density.     

Influence of the polarization of radiation on the shape of resonances of coherent population trapping on fine-structure levels

The dependence of the shape of resonances of coherent population trapping (CPT) on magnetic sublevels of thallium atoms, forming a generalized Λ-system with the magnetic sublevels of the fine-structure levels as lower ones, on the polarization of the radiation fields has been numerically studied. The cases of linear, elliptical, and circular polarizations have been considered. The shape and the number of CPT resonances for different polarizations have been compared. It has been concluded that the electromagnetically induced transparency can be changed by changing the polarization properties of the laser radiation. The possibility to decrease the number of observed resonances may be useful in high-resolution spectroscopy.     

激光对红外系统的失效机理和破坏效应研究

 根据红外光学系统的会聚特性，用光学增益方法分析了红外系统中各元件对应的光强分布，确定了位于焦面附近光学元件是激光破坏的易损部件，并提出了强激光对红外系统元件损伤,造成其探测、制导功能失效的硬破坏机理；由红外滤光片、探测器和信号处理电路与入射激光波长的光谱响应分析，提出了弱激光对红外系统干扰，导致其探测、制导功能在激光辐照一段时间内失效的软破坏机理；开展了激光辐照红外系统的失效验证实验，较好地解释了其失效的机理和效应。     

Polarization-selective grating mirrors used in the generation of radial polarization

Two novel methods to control the polarization of laser radiation are presented. The discrimination between different polarization distributions isperformed with a corrugation grating in the top high-index layer of a multilayer mirror, which couples the undesired polarization into a lossy waveguidemode of the multilayer. The generation of radially polarized radiation in a laser resonator is presented as a practical verification of the principle.This revised version was published online in May 2005. The Article Category was removed.This revised version was published online in August 2005 with a corrected cover date.     

Collisional Radiative Involvement of Molecules into Resonance with the IR Laser Field in a Two-Component Molecular Medium

Journal of Experimental and Theoretical Physics - Collisional radiative involvement of molecules not absorbing IR laser radiation into resonance with a laser field has been investigated for the...     

Peculiar properties of hot plasma formation under the influence of intense femtosecond pulses on the surface of molten metal

The peculiar properties of plasma formation on the surface of different liquid metals by femtosecond laser radiation have been studied. It is shown that plasma formation and generation of hard X-radiation on the surface of molten metal depends substantially on the contrast and weakly on the polarization of laser radiation, which clearly distinguishes the plasma produced in our experiments from the plasma generated on the surface of a solid target.     

Interaction of Low-Intensity Laser Radiation with Blood and Its Components

The response of the blood of rabbits to the intravenous irradiation by a He-Ne laser radiation (λ = 632.8 nm) has been investigated by the UV-visible and IR absorption spectra of the whole blood, plasma, and erythrocyte mass. It has been established that hemoglobin is a primary photoacceptor absorbing low-intensity He-Ne-laser radiation. The exposure of blood to this radiation causes clearly defined changes in the IR and visible absorption spectra of the blood and erythrocytes. These spectral changes arise as a result of partial photodissociation of hemoglobin-ligand complexes in the process of absorption of laser radiation. It is suggested that photodissociation is a primary reaction that arises in blood exposed to a low-intensity laser radiation.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 2, pp. 230–235, March–April, 2005.     

激光对红外系统的失效机理和破坏效应研究

根据红外光学系统的会聚特性,用光学增益方法分析了红外系统中各元件对应的光强分布,确定了位于焦面附近光学元件是激光破坏的易损部件,并提出了强激光对红外系统元件损伤,造成其探测、制导功能失效的硬破坏机理;由红外滤光片、探测器和信号处理电路与入射激光波长的光谱响应分析,提出了弱激光对红外系统干扰,导致其探测、制导功能在激光辐照一段时间内失效的软破坏机理;开展了激光辐照红外系统的失效验证实验,较好地解释了其失效的机理和效应。     

Isotope shift in the spectrum of multiquantum absorption of nitromethane molecule in intense IR fields

The effect of isotope shift has been revealed in the spectra of absorption and dissociation of polyatomic molecules in an intense IR field, with no isotope shift present in the spectrum of linear absorption of a vibration being excited. The effect has been applied to separation of nitrogen isotopes in the nitromethane molecule. The effect considered increases considerably the number of molecules suitable for isotope separation by IR laser radiation.     

Four-photon polarization spectroscopy of induced plasma oscillations in a skin layer of semiconductors

Probe-beam scattering spectra have been obtained for four-wave mixing of laser waves in the skin layer of intrinsic semiconductors. The spectra were recorded using the frequency dispersion of orthogonally polarized radiation, which arises as a result of nonlinear optical interaction with conduction-band electrons. The mixing of two counterpropagating light waves in a semiconductor, implemented under nonlinear excitation of longitudinal density oscillations in the plasma electron subsystem of the semiconductor, is theoretically considered. This mixing is shown to lead to the rotation of the probe-beam polarization vector. The results obtained are of interest, e.g., for studying optical metamaterials based on thin-film structures.     

Influence of frequency modulation of IR femtosecond laser pulse on the generation efficiency of difference frequency radiation

The results of theoretical research and numerical simulation of the generation process of difference frequency radiation by the IR femtosecond laser pulse with the frequency modulation are presented. It is shown that to obtain the maximal generation efficiency of the difference frequency radiation, the instantaneous frequency of the femtosecond IR laser pulse should be the quadratic function of time. The obtained results are independent on the type of nonlinear crystal and can be used to develop and create the pulse source of difference frequency radiation.     

Temperature Dependence of Circularly Polarized Radiation of an Injection Semiconductor Laser

JETP Letters - The temperature dependence of stimulated laser radiation with a high degree of circular polarization in chiral semiconductor nanostructures has been investigated in the temperature...     

Effect of a transverse magnetic field on the power and polarization of the radiation of a helium-neon laser at a wavelength of 3.39 μ

The dependence of the power and polarization of the radiation of a helium-neon laser on the value of a transverse magnetic field is studied. The effect of changes in the Q of the resonator under these conditions is also investigated. It is shown that it is possible for circularly polarized radiation to exist in a laser with Brewster windows.