E. F. Martynovich

Highly nonlinear fundamental mechanisms of excitation and coloring of wide-gap crystals by intense femtosecond laser pulses

Analysis of the spatial distribution of the color centers formed in wide-gap LiF and MgF2 crystals in a laser beam channel has shown that these centers are formed in numerous longitudinal filaments into which a laser beam splits when propagating in a medium. The luminescence of the produced color centers is photoluminescence, which is excited by the supercontinuum radiation in the filaments.

A method for studying the multipolarity and orientation of elementary oscillators in cubic crystals on the basis of axially periodic dependence of the luminescence intensity

A new method for determining the multipolarity and orientation of elementary quantum oscillators in cubic crystals is proposed. This method is based on studying the spatially periodic dependences of the intensity of luminescence observed in crystals with an induced anisotropy. The method was experimentally verified on LiF crystals containing F2 and F3+ color centers. It is shown that the observed spatially periodic dependences are in good agreement with the calculated dependences. The proposed method supplements the known methods for studying polarized luminescence (the methods of azimuthal dependences and polarization ratios and their various modifications). However, the new method, in contrast to the known ones, does not require measurements of the polarization ratios (for example, the degree of luminescence polarization), which in some cases significantly simplifies the experiment. Another advantage of the proposed method is its universality; i.e., it can be applied with equal success to both anisotropic and cubic crystals.

Formation of defects in lithium fluoride ceramics upon irradiation with femtosecond laser pulses

The interaction between femtosecond laser radiation in the filamentation mode and lithium fluoride optical ceramics is investigated experimentally. It is shown that irradiating optical ceramics based on lithium fluoride with femtosecond laser pulses in the near infrared spectral region effectively produces luminescence centers characteristic of radiation-colored single crystals.

Quantum trajectories of photoluminescence of F 2 centers in a LiF crystal

Single F2 color centers in a LiF crystal are studied by means of fluorescence microscopy with analysis and statistical processing of the time trajectories of fluorescence intensity. It is shown that a color center subjected to photoirradiation can enter a triplet state with a subsequent transition to a mobile state in which the center is reoriented.

Red luminescence decay kinetics in Brazilian diamonds

Luminescence kinetics in the temperature range of 80–480 K and the red region of the spectrum is studied for Brazilian diamonds. Components with decay time constants of 23 and 83 ns are observed at room temperature after being excited by laser radiation with wavelengths of 375 and 532 nm, which differs considerably from the data published earlier for the luminescence kinetics of NV0- and NV–-centers.

Modulation frequency doubling in the axially periodic dependence of the luminescence of F 3 + centers in LiF crystals

A spatially periodic distribution of the luminescence intensity of F2 and F3+ color centers is observed in LiF crystals with induced anisotropy. The period of spatially periodic modulation of the luminescence intensity generally coincides with the period of the change in the polarization state of excitation light. For F2 centers, the experimental axial spatially periodic dependence of the luminescence intensity is close to the calculated dependence obtained in the description of the absorption and radiative transitions in the centers by linear oscillators oriented along six C2 axes of the cubic crystal. However, for F3+ centers, the same experiment shows a spatially periodic distribution of luminescence intensity with a modulation period shorter by a factor of 2. It is shown that this effect of modulation frequency doubling in the spatially periodic pattern of the luminescence of color centers arises due to the nonlinear dependence of the luminescence intensity on the excitation light intensity. For F3+ centers, upon luminescence excitation in the absorption band with λmax = 452 nm, the modulation frequency doubling is due to the saturation of the metastable triplet state of such a center.

Temperature quenching of the luminescence of SiV centers in CVD diamond films

The kinetic characteristics and temperature quenching of the luminescence of optical centers of silicon vacancies (SiVs) in diamond films grown in microwave plasma on substrates of aluminum nitride and synthetic diamond are investigated via laser excitation at a wavelength of 640 nm.

Localization of 523 and 794 defects in diamond

Natural diamonds are studied via confocal scanning fluorescent spectroscopy. Defects 523 and 794 nm have a number of similar features and are associated with one another. Features of their localization in the (111) planes of the individual growth pyramids testify to their postgrowth origin and are the result of plastic deformations. The structure of the defects presumably contains dislocations. The participation of other impurities in the structures of the defects is doubtful.

Spectral properties of a Nd3+-doped Li3Ba2Gd3(MoO4)8 crystal

The spectral properties of a promising laser material, ternary molybdate Li3Ba2Gd3(MoO4)8:Nd3+, are studied (i.e., its optical absorption spectra, luminescence spectra, kinetic of luminescence decay, and temperature dependence of luminescence). Luminescence of the crystalline matrix is detected, and the temperature dependence of its intensity and reabsorption by neodymium are investigated.

Storing energy in lithium fluoride crystals irradiated with femtosecond laser pulses

The release of energy in the form of the light sum of thermally stimulated luminescence (TSL), stored under conditions of self-focusing and the multiple filamentation of femtosecond laser radiation during the interaction between model wide-bandgap dielectric crystals of lithium fluoride is studied. It is shown that F2 color centers are important centers of emission in the TSL process.