Sergei Musikhin

Transmission and reflection spectra of single-crystal germanium plates were experimentally measured in the terahertz spectral range. The optical parameters of germanium were determined at various Sb-doping levels. Saturation of the absorption index was detected with increasing wavelength in the range of 1000–3000 μm. The optical parameters of germanium correspond to the Drude-Lorentz model.

Transmission and reflection spectra of single-crystal germanium plates were experimentally measured in the terahertz spectral range. The optical parameters of germanium were determined at various Sb-doping levels. Saturation of the absorption index was detected with increasing wavelength in the range of 1000-3000 μm. The optical parameters of germanium correspond to the Drude-Lorentz model.

The luminescence properties of systems that contain lead-sulfide nanoparticles deposited onto substrates fabricated from porous silicon, oxidized porous silicon, and porous...

A review of the up-to-date methods of semiconductor colloidal quantum dots synthesis for application in biology and medicine as well as summary of sensors based on colloidal quantum dots and metal nanoparticles are presented. The principles of sensors interaction with biological objects are examined.

A procedure is described for the synthesis of nanoparticles based on lead chalcogenides. The procedure combines the synthesis of colloidal quantum dots (QDs) in aqueous solutions with simultaneous...

We demonstrate a multimodal, multifocal, differential nonlinear optical microscope, which is equipped with a pair of deformable mirrors and a Shack-Hartmann sensor for dynamic wavefront manipulation. The optical wavefronts of a home built Yb:KGW femtosecond (1028 nm) laser-beams are engineered to perform multidepth focusing in differential mode with simultaneous corrections for optical aberrations. The 39-actuator deformable mirrors provide fast reshaping of the wavefront and optical aberrations correction of the diffraction-limited focal volume allowing for fast axial scanning. Combination of ~200 frames per second lateral scanning with fast refocusing enables a three-dimensional video rate scanning capability, which is essential for studying rapid dynamics in biological organisms, such as blood flow, cardiac contractions, and motility of microorganisms in a three-dimensional volume.

Polarization characteristics and spectra of photoluminescence in CdSe nanorods suspended in liquid were investigated. Experiments demonstrated the presence of the polarization memory related to the mismatch of nanorods and solvent dielectric constants, as well as to anisotropy of optical matrix elements. Luminescent spectra contained two peaks corresponding to interband transitions between the ground and excited size-quantized states and having essentially different values of polarization memory, presumably due to different anisotropy of corresponding matrix elements. The amplitude of polarization memory decreased with the increase in concentration of nanorods confirming the hypothesis of their mutual influence.

The results of preliminary investigations toward the design of an optical biosensor instrument for the selective and direct analysis of low copy numbers of target nucleic acids in native form are reported. A concept development prototype was constructed based on a total internal reflection fluorescence (TIRF) configuration and the use of time correlated single photon counting (TCSPC). Selective detection of interfacial hybrid formation was done by identification of luminescence of characteristic (20ns) lifetime from the intercalant fluorophore ethidium bromide associated with nucleic acid hybrids formed at the interaction surface of optical sensor elements. Results of these investigations suggest that detection limits on the order of 10⁷ dye:dsDNA complexes can be achieved when an effective sensor interaction surface of 150 ¿—m diameter is used. The presence of interfacial nucleic acid duplexes at a sensor surface was further verified by thermal denaturation studies. The sensitivity of this concept design prototype was found to be most limited by long lifetime fluorescence intrinsic to the detection optics in conjunction with large amounts of scatter dispersed from the sensor cartridge. Future directions for continued device development are discussed.

We report on development of frequency-doubled diode-pumped ultrashort pulse Yb:KGW laser operating at 520 nm with approximately 200 fs long pulses at a repetition rate of 15 MHz. For ~2 W of absorbed pump power at 980 nm, the laser delivers up to 30 mW of average power at fundamental wavelength of 1040 nm, corresponding to a pulse energy of 2 nJ. The laser radiation was then frequency-doubled in a single pass configuration within a nonlinear BIBO crystal to produce femtosecond green radiation at 520 nm with peak power of ~200 W. The generated second harmonic served as excitation source of optical DNA sensor based on fluorescence lifetime measurements using the time correlated single photon counting (TCSPC) technique.