The use of three-photon absorption for optical limiting of laser radiation

The results of a study of nonlinear refraction and nonlinear absorption at a wavelength of 532 nm in an LGO (Li₂Ge₂O₁₅) crystal by Z-scan methods are presented. It is shown that the nonlinear refraction is caused by self-focusing of the laser radiation, whereas the nonlinear absorption is three-photon in nature. The possibility of using an LGO crystal for producing the optical limiting of laser radiation of picosecond duration is demonstrated.     

Qubits based on spectrally selected groups of Pr3+ ions in a LaF3 crystal

JETP Letters - Spectral selection, i.e., the separation of a group of particles with a spread in resonance frequencies smaller than the hyperfine splitting of working levels has been implemented by...     

Optimized method for solving the inverse problem for a triangular plasmonic waveguide using a response of scanning heterodyne microscope

A method proposed previously to solve the inverse problem for triangular plasmonic waveguides using a TE-polarized response of scanning differential heterodyne microscope has been optimized. The use of the phase contrast of microscope response at two wavelengths as initial data made it possible to reduce significantly the solution error and eliminate the instability domains of initial data, in which the solution error dramatically increased. It is demonstrated that the accuracy of determining the waveguide parameters significantly improves in comparison with the case where the amplitude and phase contrast of response at one wavelength are used as initial data. It is shown that the solution of the inverse problem can be further optimized using contrasts of amplitude responses as additional initial data. The dependences of the error of inverse problem solution on the error in determining the initial data are calculated.     

Influence of acetylation on the iodination of thyroglobulin and the formation of thyroxine

Summary The results obtained show that when thyroglobulin is iodinated_{in vitro} the formation in it of thyroxine from the iodotyrosine residues present in it before iodination is possible. The structure of the thyroglobulin apparently plays an important role not only in the formation of thyroxine but also in the level of iodination of the protein.Institute of Biochemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Institute of Biological and Medicinal Chemistry, Academy of Medical Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 485–488, July–August, 1978.     

Purification of isoenzyme I of phospholipase C from Clostridium perfringens

V. I. Lenin Tashkent State University. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 888–890, November–December, 1988.     

Observation of Coherent Population Trapping in Ensembles of Diamond NV-Centers under Ground-State Level Anticrossing Conditions

Optics and Spectroscopy - The coherent population trapping effect in ensembles of diamond NV-centers under ground-state level anticrossing conditions was implemented with the application of a...     

Terahertz emission from a metallic surface induced by a femtosecond optic pulse

Results of experimental and theoretical investigations on generation of terahertz radiation at the interaction of femtosecond laser pulses with a metal surface are presented. Investigations are performed with the laser pulse intensities higher compared with that used in papers [Opt. Lett.29, 2674 (2004); Opt. Lett.30, 1402 (2005)]. The most effective generation is observed for p-polarized optical pulses with incidence angles in the range 5°-10° (from the surface), depending on the kind of metal. For the copper, the exponential growth of terahertz pulse energy with the increase of optical pulse energy was registered. Theoretical interpretation for some of the experimental results is proposed based on the model of free electrons in metal.     

Determining the complex point-spread function of a scanning differential heterodyne microscope

For a scanning differential heterodyne microscope, the two-dimensional point spread function and the pupil function are determined from experimental measurements of the intensity distribution of a probing beam. The phase components of these functions were restored from the measured distributions using the Gerchberg-Saxton algorithm. Based on the two-dimensional pupil function, the three-dimensional point-spread function is determined in the scalar approximation using the Debye integral. The aberration function of the microscope is analyzed from the viewpoint of the composition of aberrations and method of their balancing. The focusing adjustment criterion of the microscope for an object under study by the phase response from the test structure is considered.